758 lines
22 KiB
Java
758 lines
22 KiB
Java
/* Integer.java -- object wrapper for int
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Copyright (C) 1998, 1999, 2001, 2002, 2004, 2005
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Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.lang;
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/**
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* Instances of class <code>Integer</code> represent primitive
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* <code>int</code> values.
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*
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* Additionally, this class provides various helper functions and variables
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* related to ints.
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*
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* @author Paul Fisher
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* @author John Keiser
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* @author Warren Levy
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* @author Eric Blake (ebb9@email.byu.edu)
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* @author Tom Tromey (tromey@redhat.com)
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* @author Andrew John Hughes (gnu_andrew@member.fsf.org)
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* @since 1.0
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* @status updated to 1.5
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*/
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public final class Integer extends Number implements Comparable<Integer>
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{
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/**
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* Compatible with JDK 1.0.2+.
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*/
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private static final long serialVersionUID = 1360826667806852920L;
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/**
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* The minimum value an <code>int</code> can represent is -2147483648 (or
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* -2<sup>31</sup>).
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*/
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public static final int MIN_VALUE = 0x80000000;
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/**
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* The maximum value an <code>int</code> can represent is 2147483647 (or
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* 2<sup>31</sup> - 1).
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*/
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public static final int MAX_VALUE = 0x7fffffff;
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/**
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* The primitive type <code>int</code> is represented by this
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* <code>Class</code> object.
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* @since 1.1
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*/
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public static final Class<Integer> TYPE = (Class<Integer>) VMClassLoader.getPrimitiveClass('I');
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/**
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* The number of bits needed to represent an <code>int</code>.
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* @since 1.5
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*/
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public static final int SIZE = 32;
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// This caches some Integer values, and is used by boxing
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// conversions via valueOf(). We must cache at least -128..127;
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// these constants control how much we actually cache.
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private static final int MIN_CACHE = -128;
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private static final int MAX_CACHE = 127;
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private static Integer[] intCache = new Integer[MAX_CACHE - MIN_CACHE + 1];
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/**
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* The immutable value of this Integer.
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*
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* @serial the wrapped int
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*/
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private final int value;
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/**
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* Create an <code>Integer</code> object representing the value of the
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* <code>int</code> argument.
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*
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* @param value the value to use
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*/
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public Integer(int value)
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{
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this.value = value;
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}
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/**
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* Create an <code>Integer</code> object representing the value of the
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* argument after conversion to an <code>int</code>.
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*
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* @param s the string to convert
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* @throws NumberFormatException if the String does not contain an int
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* @see #valueOf(String)
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*/
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public Integer(String s)
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{
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value = parseInt(s, 10, false);
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}
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/**
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* Converts the <code>int</code> to a <code>String</code> using
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* the specified radix (base). If the radix exceeds
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* <code>Character.MIN_RADIX</code> or <code>Character.MAX_RADIX</code>, 10
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* is used instead. If the result is negative, the leading character is
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* '-' ('\\u002D'). The remaining characters come from
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* <code>Character.forDigit(digit, radix)</code> ('0'-'9','a'-'z').
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*
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* @param num the <code>int</code> to convert to <code>String</code>
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* @param radix the radix (base) to use in the conversion
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* @return the <code>String</code> representation of the argument
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*/
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public static String toString(int num, int radix)
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{
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if (radix < Character.MIN_RADIX || radix > Character.MAX_RADIX)
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radix = 10;
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// For negative numbers, print out the absolute value w/ a leading '-'.
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// Use an array large enough for a binary number.
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char[] buffer = new char[33];
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int i = 33;
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boolean isNeg = false;
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if (num < 0)
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{
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isNeg = true;
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num = -num;
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// When the value is MIN_VALUE, it overflows when made positive
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if (num < 0)
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{
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buffer[--i] = digits[(int) (-(num + radix) % radix)];
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num = -(num / radix);
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}
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}
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do
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{
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buffer[--i] = digits[num % radix];
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num /= radix;
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}
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while (num > 0);
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if (isNeg)
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buffer[--i] = '-';
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// Package constructor avoids an array copy.
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return new String(buffer, i, 33 - i, true);
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}
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/**
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* Converts the <code>int</code> to a <code>String</code> assuming it is
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* unsigned in base 16.
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*
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* @param i the <code>int</code> to convert to <code>String</code>
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* @return the <code>String</code> representation of the argument
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*/
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public static String toHexString(int i)
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{
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return toUnsignedString(i, 4);
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}
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/**
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* Converts the <code>int</code> to a <code>String</code> assuming it is
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* unsigned in base 8.
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*
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* @param i the <code>int</code> to convert to <code>String</code>
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* @return the <code>String</code> representation of the argument
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*/
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public static String toOctalString(int i)
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{
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return toUnsignedString(i, 3);
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}
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/**
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* Converts the <code>int</code> to a <code>String</code> assuming it is
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* unsigned in base 2.
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*
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* @param i the <code>int</code> to convert to <code>String</code>
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* @return the <code>String</code> representation of the argument
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*/
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public static String toBinaryString(int i)
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{
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return toUnsignedString(i, 1);
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}
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/**
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* Converts the <code>int</code> to a <code>String</code> and assumes
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* a radix of 10.
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*
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* @param i the <code>int</code> to convert to <code>String</code>
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* @return the <code>String</code> representation of the argument
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* @see #toString(int, int)
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*/
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public static String toString(int i)
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{
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// This is tricky: in libgcj, String.valueOf(int) is a fast native
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// implementation. In Classpath it just calls back to
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// Integer.toString(int, int).
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return String.valueOf(i);
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}
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/**
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* Converts the specified <code>String</code> into an <code>int</code>
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* using the specified radix (base). The string must not be <code>null</code>
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* or empty. It may begin with an optional '-', which will negate the answer,
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* provided that there are also valid digits. Each digit is parsed as if by
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* <code>Character.digit(d, radix)</code>, and must be in the range
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* <code>0</code> to <code>radix - 1</code>. Finally, the result must be
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* within <code>MIN_VALUE</code> to <code>MAX_VALUE</code>, inclusive.
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* Unlike Double.parseDouble, you may not have a leading '+'.
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*
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* @param str the <code>String</code> to convert
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* @param radix the radix (base) to use in the conversion
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* @return the <code>String</code> argument converted to <code>int</code>
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* @throws NumberFormatException if <code>s</code> cannot be parsed as an
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* <code>int</code>
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*/
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public static int parseInt(String str, int radix)
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{
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return parseInt(str, radix, false);
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}
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/**
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* Converts the specified <code>String</code> into an <code>int</code>.
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* This function assumes a radix of 10.
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*
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* @param s the <code>String</code> to convert
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* @return the <code>int</code> value of <code>s</code>
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* @throws NumberFormatException if <code>s</code> cannot be parsed as an
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* <code>int</code>
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* @see #parseInt(String, int)
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*/
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public static int parseInt(String s)
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{
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return parseInt(s, 10, false);
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}
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/**
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* Creates a new <code>Integer</code> object using the <code>String</code>
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* and specified radix (base).
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*
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* @param s the <code>String</code> to convert
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* @param radix the radix (base) to convert with
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* @return the new <code>Integer</code>
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* @throws NumberFormatException if <code>s</code> cannot be parsed as an
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* <code>int</code>
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* @see #parseInt(String, int)
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*/
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public static Integer valueOf(String s, int radix)
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{
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return new Integer(parseInt(s, radix, false));
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}
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/**
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* Creates a new <code>Integer</code> object using the <code>String</code>,
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* assuming a radix of 10.
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*
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* @param s the <code>String</code> to convert
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* @return the new <code>Integer</code>
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* @throws NumberFormatException if <code>s</code> cannot be parsed as an
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* <code>int</code>
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* @see #Integer(String)
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* @see #parseInt(String)
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*/
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public static Integer valueOf(String s)
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{
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return new Integer(parseInt(s, 10, false));
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}
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/**
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* Returns an <code>Integer</code> object wrapping the value.
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* In contrast to the <code>Integer</code> constructor, this method
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* will cache some values. It is used by boxing conversion.
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*
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* @param val the value to wrap
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* @return the <code>Integer</code>
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*/
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public static Integer valueOf(int val)
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{
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if (val < MIN_CACHE || val > MAX_CACHE)
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return new Integer(val);
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synchronized (intCache)
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{
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if (intCache[val - MIN_CACHE] == null)
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intCache[val - MIN_CACHE] = new Integer(val);
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return intCache[val - MIN_CACHE];
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}
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}
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/**
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* Return the value of this <code>Integer</code> as a <code>byte</code>.
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*
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* @return the byte value
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*/
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public byte byteValue()
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{
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return (byte) value;
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}
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/**
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* Return the value of this <code>Integer</code> as a <code>short</code>.
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*
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* @return the short value
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*/
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public short shortValue()
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{
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return (short) value;
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}
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/**
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* Return the value of this <code>Integer</code>.
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* @return the int value
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*/
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public int intValue()
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{
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return value;
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}
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/**
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* Return the value of this <code>Integer</code> as a <code>long</code>.
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*
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* @return the long value
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*/
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public long longValue()
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{
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return value;
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}
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/**
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* Return the value of this <code>Integer</code> as a <code>float</code>.
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*
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* @return the float value
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*/
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public float floatValue()
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{
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return value;
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}
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/**
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* Return the value of this <code>Integer</code> as a <code>double</code>.
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*
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* @return the double value
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*/
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public double doubleValue()
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{
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return value;
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}
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/**
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* Converts the <code>Integer</code> value to a <code>String</code> and
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* assumes a radix of 10.
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*
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* @return the <code>String</code> representation
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*/
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public String toString()
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{
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return String.valueOf(value);
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}
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/**
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* Return a hashcode representing this Object. <code>Integer</code>'s hash
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* code is simply its value.
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*
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* @return this Object's hash code
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*/
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public int hashCode()
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{
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return value;
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}
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/**
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* Returns <code>true</code> if <code>obj</code> is an instance of
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* <code>Integer</code> and represents the same int value.
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*
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* @param obj the object to compare
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* @return whether these Objects are semantically equal
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*/
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public boolean equals(Object obj)
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{
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return obj instanceof Integer && value == ((Integer) obj).value;
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}
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/**
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* Get the specified system property as an <code>Integer</code>. The
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* <code>decode()</code> method will be used to interpret the value of
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* the property.
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*
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* @param nm the name of the system property
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* @return the system property as an <code>Integer</code>, or null if the
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* property is not found or cannot be decoded
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* @throws SecurityException if accessing the system property is forbidden
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* @see System#getProperty(String)
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* @see #decode(String)
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*/
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public static Integer getInteger(String nm)
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{
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return getInteger(nm, null);
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}
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/**
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* Get the specified system property as an <code>Integer</code>, or use a
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* default <code>int</code> value if the property is not found or is not
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* decodable. The <code>decode()</code> method will be used to interpret
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* the value of the property.
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*
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* @param nm the name of the system property
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* @param val the default value
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* @return the value of the system property, or the default
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* @throws SecurityException if accessing the system property is forbidden
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* @see System#getProperty(String)
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* @see #decode(String)
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*/
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public static Integer getInteger(String nm, int val)
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{
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Integer result = getInteger(nm, null);
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return result == null ? new Integer(val) : result;
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}
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/**
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* Get the specified system property as an <code>Integer</code>, or use a
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* default <code>Integer</code> value if the property is not found or is
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* not decodable. The <code>decode()</code> method will be used to
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* interpret the value of the property.
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*
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* @param nm the name of the system property
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* @param def the default value
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* @return the value of the system property, or the default
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* @throws SecurityException if accessing the system property is forbidden
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* @see System#getProperty(String)
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* @see #decode(String)
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*/
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public static Integer getInteger(String nm, Integer def)
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{
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if (nm == null || "".equals(nm))
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return def;
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nm = System.getProperty(nm);
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if (nm == null)
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return def;
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try
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{
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return decode(nm);
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}
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catch (NumberFormatException e)
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{
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return def;
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}
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}
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/**
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* Convert the specified <code>String</code> into an <code>Integer</code>.
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* The <code>String</code> may represent decimal, hexadecimal, or
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* octal numbers.
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*
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* <p>The extended BNF grammar is as follows:<br>
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* <pre>
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* <em>DecodableString</em>:
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* ( [ <code>-</code> ] <em>DecimalNumber</em> )
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* | ( [ <code>-</code> ] ( <code>0x</code> | <code>0X</code>
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* | <code>#</code> ) <em>HexDigit</em> { <em>HexDigit</em> } )
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* | ( [ <code>-</code> ] <code>0</code> { <em>OctalDigit</em> } )
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* <em>DecimalNumber</em>:
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* <em>DecimalDigit except '0'</em> { <em>DecimalDigit</em> }
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* <em>DecimalDigit</em>:
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* <em>Character.digit(d, 10) has value 0 to 9</em>
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* <em>OctalDigit</em>:
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* <em>Character.digit(d, 8) has value 0 to 7</em>
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* <em>DecimalDigit</em>:
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* <em>Character.digit(d, 16) has value 0 to 15</em>
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* </pre>
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* Finally, the value must be in the range <code>MIN_VALUE</code> to
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* <code>MAX_VALUE</code>, or an exception is thrown.
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*
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* @param str the <code>String</code> to interpret
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* @return the value of the String as an <code>Integer</code>
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* @throws NumberFormatException if <code>s</code> cannot be parsed as a
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* <code>int</code>
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* @throws NullPointerException if <code>s</code> is null
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* @since 1.2
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*/
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public static Integer decode(String str)
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{
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return new Integer(parseInt(str, 10, true));
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}
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/**
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* Compare two Integers numerically by comparing their <code>int</code>
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* values. The result is positive if the first is greater, negative if the
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* second is greater, and 0 if the two are equal.
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*
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* @param i the Integer to compare
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* @return the comparison
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* @since 1.2
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*/
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public int compareTo(Integer i)
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{
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if (value == i.value)
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return 0;
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// Returns just -1 or 1 on inequality; doing math might overflow.
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return value > i.value ? 1 : -1;
|
|
}
|
|
|
|
/**
|
|
* Return the number of bits set in x.
|
|
* @param x value to examine
|
|
* @since 1.5
|
|
*/
|
|
public static int bitCount(int x)
|
|
{
|
|
// Successively collapse alternating bit groups into a sum.
|
|
x = ((x >> 1) & 0x55555555) + (x & 0x55555555);
|
|
x = ((x >> 2) & 0x33333333) + (x & 0x33333333);
|
|
x = ((x >> 4) & 0x0f0f0f0f) + (x & 0x0f0f0f0f);
|
|
x = ((x >> 8) & 0x00ff00ff) + (x & 0x00ff00ff);
|
|
return ((x >> 16) & 0x0000ffff) + (x & 0x0000ffff);
|
|
}
|
|
|
|
/**
|
|
* Rotate x to the left by distance bits.
|
|
* @param x the value to rotate
|
|
* @param distance the number of bits by which to rotate
|
|
* @since 1.5
|
|
*/
|
|
public static int rotateLeft(int x, int distance)
|
|
{
|
|
// This trick works because the shift operators implicitly mask
|
|
// the shift count.
|
|
return (x << distance) | (x >>> - distance);
|
|
}
|
|
|
|
/**
|
|
* Rotate x to the right by distance bits.
|
|
* @param x the value to rotate
|
|
* @param distance the number of bits by which to rotate
|
|
* @since 1.5
|
|
*/
|
|
public static int rotateRight(int x, int distance)
|
|
{
|
|
// This trick works because the shift operators implicitly mask
|
|
// the shift count.
|
|
return (x << - distance) | (x >>> distance);
|
|
}
|
|
|
|
/**
|
|
* Find the highest set bit in value, and return a new value
|
|
* with only that bit set.
|
|
* @param value the value to examine
|
|
* @since 1.5
|
|
*/
|
|
public static int highestOneBit(int value)
|
|
{
|
|
value |= value >>> 1;
|
|
value |= value >>> 2;
|
|
value |= value >>> 4;
|
|
value |= value >>> 8;
|
|
value |= value >>> 16;
|
|
return value ^ (value >>> 1);
|
|
}
|
|
|
|
/**
|
|
* Return the number of leading zeros in value.
|
|
* @param value the value to examine
|
|
* @since 1.5
|
|
*/
|
|
public static int numberOfLeadingZeros(int value)
|
|
{
|
|
value |= value >>> 1;
|
|
value |= value >>> 2;
|
|
value |= value >>> 4;
|
|
value |= value >>> 8;
|
|
value |= value >>> 16;
|
|
return bitCount(~value);
|
|
}
|
|
|
|
/**
|
|
* Find the lowest set bit in value, and return a new value
|
|
* with only that bit set.
|
|
* @param value the value to examine
|
|
* @since 1.5
|
|
*/
|
|
public static int lowestOneBit(int value)
|
|
{
|
|
// Classic assembly trick.
|
|
return value & - value;
|
|
}
|
|
|
|
/**
|
|
* Find the number of trailing zeros in value.
|
|
* @param value the value to examine
|
|
* @since 1.5
|
|
*/
|
|
public static int numberOfTrailingZeros(int value)
|
|
{
|
|
return bitCount((value & -value) - 1);
|
|
}
|
|
|
|
/**
|
|
* Return 1 if x is positive, -1 if it is negative, and 0 if it is
|
|
* zero.
|
|
* @param x the value to examine
|
|
* @since 1.5
|
|
*/
|
|
public static int signum(int x)
|
|
{
|
|
return x < 0 ? -1 : (x > 0 ? 1 : 0);
|
|
}
|
|
|
|
/**
|
|
* Reverse the bytes in val.
|
|
* @since 1.5
|
|
*/
|
|
public static int reverseBytes(int val)
|
|
{
|
|
return ( ((val >> 24) & 0xff)
|
|
| ((val >> 8) & 0xff00)
|
|
| ((val << 8) & 0xff0000)
|
|
| ((val << 24) & 0xff000000));
|
|
}
|
|
|
|
/**
|
|
* Reverse the bits in val.
|
|
* @since 1.5
|
|
*/
|
|
public static int reverse(int val)
|
|
{
|
|
// Successively swap alternating bit groups.
|
|
val = ((val >> 1) & 0x55555555) + ((val << 1) & ~0x55555555);
|
|
val = ((val >> 2) & 0x33333333) + ((val << 2) & ~0x33333333);
|
|
val = ((val >> 4) & 0x0f0f0f0f) + ((val << 4) & ~0x0f0f0f0f);
|
|
val = ((val >> 8) & 0x00ff00ff) + ((val << 8) & ~0x00ff00ff);
|
|
return ((val >> 16) & 0x0000ffff) + ((val << 16) & ~0x0000ffff);
|
|
}
|
|
|
|
/**
|
|
* Helper for converting unsigned numbers to String.
|
|
*
|
|
* @param num the number
|
|
* @param exp log2(digit) (ie. 1, 3, or 4 for binary, oct, hex)
|
|
*/
|
|
// Package visible for use by Long.
|
|
static String toUnsignedString(int num, int exp)
|
|
{
|
|
// Use an array large enough for a binary number.
|
|
int mask = (1 << exp) - 1;
|
|
char[] buffer = new char[32];
|
|
int i = 32;
|
|
do
|
|
{
|
|
buffer[--i] = digits[num & mask];
|
|
num >>>= exp;
|
|
}
|
|
while (num != 0);
|
|
|
|
// Package constructor avoids an array copy.
|
|
return new String(buffer, i, 32 - i, true);
|
|
}
|
|
|
|
/**
|
|
* Helper for parsing ints, used by Integer, Short, and Byte.
|
|
*
|
|
* @param str the string to parse
|
|
* @param radix the radix to use, must be 10 if decode is true
|
|
* @param decode if called from decode
|
|
* @return the parsed int value
|
|
* @throws NumberFormatException if there is an error
|
|
* @throws NullPointerException if decode is true and str if null
|
|
* @see #parseInt(String, int)
|
|
* @see #decode(String)
|
|
* @see Byte#parseByte(String, int)
|
|
* @see Short#parseShort(String, int)
|
|
*/
|
|
static int parseInt(String str, int radix, boolean decode)
|
|
{
|
|
if (! decode && str == null)
|
|
throw new NumberFormatException();
|
|
int index = 0;
|
|
int len = str.length();
|
|
boolean isNeg = false;
|
|
if (len == 0)
|
|
throw new NumberFormatException("string length is null");
|
|
int ch = str.charAt(index);
|
|
if (ch == '-')
|
|
{
|
|
if (len == 1)
|
|
throw new NumberFormatException("pure '-'");
|
|
isNeg = true;
|
|
ch = str.charAt(++index);
|
|
}
|
|
if (decode)
|
|
{
|
|
if (ch == '0')
|
|
{
|
|
if (++index == len)
|
|
return 0;
|
|
if ((str.charAt(index) & ~('x' ^ 'X')) == 'X')
|
|
{
|
|
radix = 16;
|
|
index++;
|
|
}
|
|
else
|
|
radix = 8;
|
|
}
|
|
else if (ch == '#')
|
|
{
|
|
radix = 16;
|
|
index++;
|
|
}
|
|
}
|
|
if (index == len)
|
|
throw new NumberFormatException("non terminated number: " + str);
|
|
|
|
int max = MAX_VALUE / radix;
|
|
// We can't directly write `max = (MAX_VALUE + 1) / radix'.
|
|
// So instead we fake it.
|
|
if (isNeg && MAX_VALUE % radix == radix - 1)
|
|
++max;
|
|
|
|
int val = 0;
|
|
while (index < len)
|
|
{
|
|
if (val < 0 || val > max)
|
|
throw new NumberFormatException("number overflow (pos=" + index + ") : " + str);
|
|
|
|
ch = Character.digit(str.charAt(index++), radix);
|
|
val = val * radix + ch;
|
|
if (ch < 0 || (val < 0 && (! isNeg || val != MIN_VALUE)))
|
|
throw new NumberFormatException("invalid character at position " + index + " in " + str);
|
|
}
|
|
return isNeg ? -val : val;
|
|
}
|
|
}
|