java源码——Long

private static class LongCache {  
    private LongCache(){}  
  
    static final Long cache[] = new Long[-(-128) + 127 + 1];  
  
    static {  
        for(int i = 0; i < cache.length; i++)  
        cache[i] = new Long(i - 128);  
    }  
    } 

 public static Long valueOf(long l) {
	final int offset = 128;
	if (l &gt;= -128 &amp;&amp; l &lt;= 127) { // will cache
	    return LongCache.cache[(int)l + offset];
	}
        return new Long(l);
    }

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