private static class ByteCache {
private ByteCache(){}
//256个元素,用于缓存-128到127
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));
}
}
Byte的valueof方法
public static Byte valueOf(byte b) {
final int offset = 128;
return ByteCache.cache[(int)b + offset];
}