java值传递与引用传递小例子

public class Example{
    String str=new String("hello");
    //char[]ch={'a','b'};
    public static void main(String args[]){
        Example ex=new Example();
        //ex.change(ex.str,ex.ch);
        //ex.change();
        ex.change(ex.str);
        System.out.print(ex.str+" and ");
        //System.out.print(ex.ch);
     }
        //public void change(String str,char ch[]){
    public void change(String str){
        //public void change(){
        System.out.println("局部变量参数值（局部值等于全局值）"+str);
        str="test ok";
      System.out.println("局部变量参数值2（变了）"+str);
      System.out.println("全局参数（没变）"+this.str);
      //ch[0]='c';
    }
}