### 常用API * getURLs\(\)子类URLClassLoader方法，用于获取系统环境路径 * JDK对Short、Integer、Byte的缓存 ``` // Integer缓存(range [-128, 127] must be interned(JLS7 5.1.7)) Integer a = new Integer(10); Integer b = 10; Integer c = Integer.valueOf(10); Integer d = new Integer("10"); System.err.println(a == b); System.err.println(b == d); System.err.println(a == d); System.err.println(b == c); out =====> false false false true ```