Android方法的传递值及其改变

MainActivity如下:

package cn.testchangevar;import android.os.Bundle;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.app.Activity;/** * Demo描述: * Java中的传值及其改变 * */public class MainActivity extends Activity {private int id=7;private Person mPerson;    private Button mButton;    private String mString;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main);init();}   private void init(){    mString=new String("OOOOO");    mPerson=new Person("xx", 22);    mButton=(Button) findViewById(R.id.button);    mButton.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View view) {System.out.println("111 id="+id);System.out.println("111 mString="+mString);System.out.println("111 mPerson.getAge()="+mPerson.getAge());System.out.println("=========================");Util.change(id);Util.change(mString);Util.change(mPerson);System.out.println("=========================");System.out.println("222 id="+id);System.out.println("222 mString="+mString);System.out.println("222 mPerson.getAge()="+mPerson.getAge());}});   }}

Util如下:

package cn.testchangevar;public class Util {   //不可以改变.因为int属于基础类型   public static void change(int i){   i=9527;   System.out.println("has been changed i="+i);   }     //可以改变.传递的是对象   public static void change(Person person){   person.setAge(88);   System.out.println("has been changed string="+person);   }      //不可以改变.虽然String也是对象,但是较为特殊   public static void change(String string){   string="XXXXX";   System.out.println("has been changed string="+string);   }}

Person如下:

package cn.testchangevar;public class Person {    private String name;    private int age;public Person(String name, int age) {super();this.name = name;this.age = age;}public String getName() {return name;}public void setName(String name) {this.name = name;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}@Overridepublic String toString() {return "Person [name=" + name + ", age=" + age + "]";}}

main.xml如下:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"     >    <Button        android:id="@+id/button"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="@string/hello_world"        android:layout_centerInParent="true"    /></RelativeLayout>

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