【java】intern方法实践

今天心血来潮，看了看java笔试题，其中有人提到intern的方法，我暂且测试一番。

public static void main(String[] args) {
		String s = new String("abc");
		String b = s.intern();
		if (s == b) {
			System.out.println("字符串abc在常量池中");
		} else {
			System.out.println("字符串abc不在常量池中");
		}

		String s1 = "abc";
		String b1 = s1.intern();
		if (s1 == b1) {
			System.out.println("字符串abc在常量池中");
		} else {
			System.out.println("字符串abc不在常量池中");
		}
	}

结果：
字符串abc不在常量池中
字符串abc在常量池中

详见jdk
public native String intern();

if the pool already contains a string equal to this String object,
then the string from the pool is returned. Otherwise, this String object  is added to the pool and a reference to this String object is returned.
说明b和b1都是来自pool的。而new的Object是动态heap上的，这也从侧面证明了
String s = new String("123");创建几个对象的原理