java字符串類型String測試

public class StringDemo {
	public void test() {
		String a = "a";
		String b="a";
		String c=a;
		String aa = new String("a");
		String bb = new String("a");
		String cc = aa;
		String ab = "ab";
		String ab2 = "a"+"b";
		String ab3 = a + b;
		String ab4 = aa + bb;
		System.out.println();
		System.out.println(String.format("a==b：%s",a==b));
		System.out.println(String.format("a==c：%s",a==c));		
		System.out.println(String.format("a==aa：%s",a==aa));
		System.out.println(String.format("a==bb：%s",a==bb));
		System.out.println(String.format("a==cc：%s",a==cc));
		System.out.println(String.format("aa==bb：%s",aa==bb));
		System.out.println(String.format("aa==cc：%s",aa==cc));
		System.out.println(String.format("ab==ab2：%s",ab==ab2));
		System.out.println(String.format("ab==ab3：%s",ab==ab3));
		System.out.println(String.format("ab==ab4：%s",ab==ab4));
	}
}

結果：

a==b：true
a==c：true
a==aa：false
a==bb：false
a==cc：false
aa==bb：false
aa==cc：true
ab==ab2：true
ab==ab3：false
ab==ab4：false

內存標識：