jdk-包装类型缓存池

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8中基本数据类型及对应的封装类型:

• boolean/1 --public final class Boolean implements java.io.Serializable,Comparable<Boolean>
• byte/8 --public final class Byte extends Number implements Comparable<Byte>
• char/16 --public final class Character implements java.io.Serializable, Comparable<Character>
• short/16 --public final class Short extends Number implements Comparable<Short>
• int/32 --public final class Integer extends Number implements Comparable<Integer>
• float/32 --public final class Float extends Number implements Comparable<Float>
• long/64 --public final class Long extends Number implements Comparable<Long>
• double/64 --public final class Double extends Number implements Comparable<Double>

缓存池:

1、类型

private static class 

2、常见缓存池

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

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

IntegerCache           
static final int low = -128;
上限不固定，常见的是127，可通过更改jvm 参数-Djava.lang.Integer.IntegerCache.high=##,修改上限，最大不能大于Integer.MAX_VALUE - (-low) -1

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

CharacterCache        
static final Character cache[] = new Character[127 + 1];

Boolean   
public static final Boolean TRUE = new Boolean(true);
public static final Boolean FALSE = new Boolean(false);