深入学习java源码之ByteCache()与parseByte()
Byte类在一个对象中包含一个基本类型byte的值。 类型为Byte的对象包含一个单一字段,其类型为byte 。
此外,该类还提供了一些将byte转换为String和String转换为byte ,以及在处理byte时有用的其他常量和方法。
方法
Modifier and Type | Method and Description |
---|---|
byte |
byteValue() 将 |
static int |
compare(byte x, byte y) 数值比较两个 |
int |
compareTo(Byte anotherByte) 数字比较两个 |
static Byte |
decode(String nm) 将 |
double |
doubleValue() 返回此值 |
boolean |
equals(Object obj) 将此对象与指定的对象进行比较。 |
float |
floatValue() 返回此值 |
int |
hashCode() 返回这个 |
static int |
hashCode(byte value) 返回一个 |
int |
intValue() 返回此的值 |
long |
longValue() 返回此值 |
static byte |
parseByte(String s) 将字符串参数解析为带符号的十进制 |
static byte |
parseByte(String s, int radix) 将字符串参数解析为第二个参数指定的基数中的带符号的 |
short |
shortValue() 返回此值 |
String |
toString() 返回一个 |
static String |
toString(byte b) 返回一个新的 |
static int |
toUnsignedInt(byte x) 的参数的转换 |
static long |
toUnsignedLong(byte x) 参数给转换 |
static Byte |
valueOf(byte b) 返回一个 |
static Byte |
valueOf(String s) 返回一个 |
static Byte |
valueOf(String s, int radix) 返回一个 |
java源码
package java.lang;
public final class Byte extends Number implements Comparable<Byte> {
public static final byte MIN_VALUE = -128;
public static final byte MAX_VALUE = 127;
@SuppressWarnings("unchecked")
public static final Class<Byte> TYPE = (Class<Byte>) Class.getPrimitiveClass("byte");
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;
/** use serialVersionUID from JDK 1.1. for interoperability */
private static final long serialVersionUID = -7183698231559129828L;
}
package java.lang;
public abstract class Number implements java.io.Serializable {
public abstract int intValue();
public abstract long longValue();
public abstract float floatValue();
public abstract double doubleValue();
public byte byteValue() {
return (byte)intValue();
}
public short shortValue() {
return (short)intValue();
}
/** use serialVersionUID from JDK 1.0.2 for interoperability */
private static final long serialVersionUID = -8742448824652078965L;
}
package java.lang;
import java.util.*;
public interface Comparable<T> {
public int compareTo(T o);
}