IntegerCache

/** * 本类是JDK源码中的示例,思维很巧 * @author TANGHAI * */ class IntegerCache { private IntegerCache() { } static final Integer cache[] = new Integer[-(-128) + 127 + 1]; static { for (int i = 0; i < cache.length; i++) cache[i] = new Integer(i - 128); } public static void main(String[] args) { System.out.println(cache.length); for (Integer i : cache) { System.out.println(i); } } }