java参数传递之值传递和引用传递

public class Assc
{
 public static void main(String[] args)
 {
 int x1=1;
 add(x1);
 System.out.println("最终"+x1);//1
 Integer x2=new Integer(1);
 sub(x2);
 System.out.println("最终"+x2);//1
 }
 public static void add(int x) {
 x++;
 System.out.println(x); //2
 }
 public static void sub(Integer x) {
 x--;
 System.out.println(x);//0
 }
 
}

public class Assc
{
 public static void main(String[] args)
 {
 String str="hello";
 combine(str);
 System.out.println("最终"+str);//hello
 StringBuilder sb=new StringBuilder("nihao");
 combine2(sb);
 System.out.println("最终"+sb);//nihaoworld
 }
 
 public static void combine(String str) {
 str+="world";
 System.out.println(str);//helloworld
 }
 public static void combine2(StringBuilder str) {
 str.append("world");
 System.out.println(str);//nihaoworld
 }
}