JDK源码阅读（7）：Byte类

最新推荐文章于 2025-06-04 18:00:08 发布

原创最新推荐文章于 2025-06-04 18:00:08 发布 · 249 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#Byte源码

JDK源码专栏收录该内容

22 篇文章

订阅专栏

本文深入解析Java中的Byte类，涵盖其基本属性、方法实现及内部类ByteCache的使用。介绍了Byte类如何转换、解析字符串为byte值，以及比较、哈希码生成等功能，适合Java开发者深入了解标准库。

public final class Byte extends Number implements Comparable<Byte> {

    public static final byte   MIN_VALUE = -128;

    public static final byte   MAX_VALUE = 127;

    public static String toString(byte b) {
        return Integer.toString((int)b, 10);
    }

    private static class ByteCache {
        private ByteCache(){}

        static final Byte cache[] = new Byte[-(-128) + 127 + 1];

        static {
            for(int i = 0; i < cache.length; i++)
                cache[i] = new Byte((byte)(i - 128));
        }
    }

    public static Byte valueOf(byte b) {
        final int offset = 128;
        return ByteCache.cache[(int)b + offset];
    }

  
    public static byte parseByte(String s, int radix)
        throws NumberFormatException {
        int i = Integer.parseInt(s, radix);
        if (i < MIN_VALUE || i > MAX_VALUE)
            throw new NumberFormatException(
                "Value out of range. Value:\"" + s + "\" Radix:" + radix);
        return (byte)i;
    }

    public static byte parseByte(String s) throws NumberFormatException {
        return parseByte(s, 10);
    }

    public static Byte valueOf(String s, int radix)
        throws NumberFormatException {
        return valueOf(parseByte(s, radix));
    }

    
    public static Byte valueOf(String s) throws NumberFormatException {
        return valueOf(s, 10);
    }

    
    public static Byte decode(String nm) throws NumberFormatException {
        int i = Integer.decode(nm);
        if (i < MIN_VALUE || i > MAX_VALUE)
            throw new NumberFormatException(
                    "Value " + i + " out of range from input " + nm);
        return valueOf((byte)i);
    }

   
    private final byte value;

  
    public Byte(byte value) {
        this.value = value;
    }

    public Byte(String s) throws NumberFormatException {
        this.value = parseByte(s, 10);
    }

   
    public byte byteValue() {
        return value;
    }

   
    public short shortValue() {
        return (short)value;
    }

   
    public int intValue() {
        return (int)value;
    }

    public long longValue() {
        return (long)value;
    }

    public float floatValue() {
        return (float)value;
    }

    public double doubleValue() {
        return (double)value;
    }

    public String toString() {
        return Integer.toString((int)value);
    }

    @Override
    public int hashCode() {
        return Byte.hashCode(value);
    }

    public static int hashCode(byte value) {
        return (int)value;
    }

    public boolean equals(Object obj) {
        if (obj instanceof Byte) {
            return value == ((Byte)obj).byteValue();
        }
        return false;
    }

    public int compareTo(Byte anotherByte) {
        return compare(this.value, anotherByte.value);
    }

  
    public static int compare(byte x, byte y) {
        return x - y;
    }

   
    public static int toUnsignedInt(byte x) {
        return ((int) x) & 0xff;
    }

    public static long toUnsignedLong(byte x) {
        return ((long) x) & 0xffL;
    }


 
    public static final int SIZE = 8;

 
    public static final int BYTES = SIZE / Byte.SIZE;

    private static final long serialVersionUID = -7183698231559129828L;
}