@HotSpotIntrinsicCandidate
public static Integer value0f(int i){
    if(i>= IntegerCache.low && i<= IntegerCache.high)  //如果傳入的int值在緩存范圍內(nèi)，則直接從緩存中返回Integer對(duì)象
        return IntegerCache.cache[i+(-IntegerCache.low)];
    return new Integer(i);                              //否則，創(chuàng)建新的Integer對(duì)象
}
private static class IntegerCache{
    static final int low=-128;
    static final int high;
    static final Integer cache[];
    static {
        // high value may be configured by property
        int h = 127;
        String integerCacheHighPropValue = VM.getSavedProperty( key:"java.lang.Integer.IntegerCache.high");
        if(integerCacheHighPropValue != null){
            try {
                int i = parseInt(integerCacheHighPropValue);
                i = Math.max(i，127);
                // Maximum array size is Integer.MAX_VALUE
                h= Math.min(i,Integer.MAX_VALUE-(-low)-1);
            }catch( NumberFormatException nfe){
            //If the property cannot be parsed into an int, ignore it.
            }
        }
        high = h;
        
        cache =new Integer[(high-low)+1];
        int i = low;
        for(int k=0;k< cache.length; k++)    //遍歷創(chuàng)建-128-127的所有對(duì)象
            cache[k]= new Integer(i++);
        assert IntegerCache.high >= 127;
    }
    
    private IntegerCache(){}
}

@HotSpotIntrinsicCandidate
public static Long value0f(long l){
    final int offset = 128;
    if(l>= -128 &&l<= 127){ // will cache
        return LongCache.cache[(int)l + offsetl];
    }
    return new Long(l);
}