封装类及String类需要注意的地方

  Integer a = new Integer(1);
  Integer a1 = a;
  a++;
  System.out.println(a == a1);

 

结果这：false

 

		String s = new String("a");
		String s1 = s;
		s1 = s1 + "b";
		System.out.println(s == s1);

 

结果为：false

 

		StringBuffer sb=new StringBuffer("a");
		StringBuffer sb1=sb;
		sb.append("b");
		System.out.println(sb == sb1);

 

结果为：true