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;
	@Override
	protected 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() {
			@Override
			public 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;
	}
	@Override
	public 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>