StringBuffer和String 的例子

public class Example {
  String str = new String("good");
  static StringBuffer sbf=new StringBuffer();
  char[] ch = {‘a‘,‘b‘,‘c‘};
  public static void main(String[] args) {
     Example ex = new Example();
     ex.change(ex.str, ex.ch);
     System.out.print(ex.str +"and"); //string是不变的，goodand
     System.out.print(ex.ch);//gbc
     //参考答案输出结果：goodandgbc
     change2(sbf);
     System.out.println(sbf); //sbf改变了
  }
 
  public void change(String str, char ch[]){
     str= "test ok";
     ch[0]= ‘g‘;
  }
  public static void change2(StringBuffer sbf)
  {
      sbf.append("333");
  }
}