java面试题： StringBuffer a=new StringBuffer("A"); StringBuffer b=new StringBuffer("B

Posted 2022-08-18 Coding With you.....

题目： System.out.println(a+","+b); 的值为什么

class Client_port 
	 public static void main(String[] args) 
		   StringBuffer a=new StringBuffer("A"); 
		   StringBuffer b=new StringBuffer("B"); 
		   operate(a,b); 
		   System.out.println("a为"+a);
		   System.out.println("b为"+b);
		   System.out.println(a+","+b); 
		 
		public static void operate(StringBuffer x, StringBuffer y) 
		    x.append(y); 
		   
		    y=x; 
		    System.out.println("y为"+y);
		 
	     

结果：

看到这个答案是疑惑的，应该为AB,AB，查阅资料后这是引用类型。下面解释：

a指向A，b指向B,

operate():x指向A，y指向B----------------调用方法：x指向AB，y指向了X为AB

之后：a指向的值变成了AB，b指向的还是B