activity之间通过全局变量传递数据

一、简介

Application域中的onCreate方法是Android程序的入口，Android程序运行的时候就自动加载Application的对象，感觉Main方法应该是封装在这个里面的。 

activity中传递数据主要用intent方式和全局变量方式。

 

二、使用步骤

1、新建MyApplication类继承Application类

public class MyApplication extends Application

继承之后MyApplication类就是全局的了

2、在传输数据页面调用MyApplication类并生成数据

MyApplication app=(MyApplication) getApplication();

app.setName("fry");
app.setAge(22);

3、在接收数据页面调用MyApplication类并输出数据

MyApplication app=(MyApplication) getApplication();

tv_answer.setText("app:" + app );

4、在AndroidManifest.xml配置文件中添加MyApplication类的Android启动配置

android:name="activityGlobelVariable.MyApplication"

5、大功告成

 

三、具体代码实例

代码中进行了两次优化：

一是对MyApplication类实现了单例化模式，便于在没有继承Activity的类里面调用

调用：

MyApplication app = MyApplication.getInstance();

二是对于传输多组数据，使用了HashMap

private HashMap<String, Object> map=new HashMap<String, Object>();

 

结果图：

activityGlobelVariable.MyApplication

package activityGlobelVariable;

import java.util.HashMap;

import android.app.Application;

public class MyApplication extends Application{
    
    
    //也可以用hashMap来代替这些私有变量
    private HashMap<String, Object> map=new HashMap<String, Object>();  12             
    
    private String name;
    private int age;
    
    
    
    
    
    public HashMap<String, Object> getMap() {
        return map;
    }

    public void setMap(HashMap<String, Object> map) {
        this.map = map;
    }











 39 private static MyApplication instance=null; 40 41 public static MyApplication getInstance(){ 42 return instance; 43 }  44     
    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;
    }
    
    


    public MyApplication() {
        super();
    }



    public MyApplication(String name, int age) {
        super();
        this.name = name;
        this.age = age;
    }



    @Override
 86 public void onCreate() { 87 // TODO Auto-generated method stub 88 super.onCreate(); 89 this.instance=this; 90 }  91 
    

    

    

    



    @Override
    public String toString() {
        return "MyApplication [name=" + name + ", age=" + age + "]";
    }
    
    
    
    
}

activityGlobelVariable.MainActivity

package activityGlobelVariable;




import com.example.activityGlobelVariable.R;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;



public class MainActivity extends Activity{
    private Button btn_openActivty;//创建一个button对象
    MyApplication app = MyApplication.getInstance(); 20      protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);//父类操作
            setContentView(R.layout.activity_main);//引入名为activity_main的界面
            btn_openActivty=(Button) findViewById(R.id.btn_openActivity);//找id为btn_openActivity的button
            btn_openActivty.setOnClickListener(new OnClickListener() {//设置button点击监听
                
                @Override
                public void onClick(View v) {//