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多個Activity中經常使用同一變數時,使用Bundle則每次調用Activity都要設定。在android中想在整個應用中不同Activity多次重複使用相同的變數時利用使用Application
context可以方便的實現。
1、建立一個儲存資料的類,繼承自Application
package activity.com;import android.app.Application;public class MyApp extends Application{ private String myState="start"; public String getState(){ return myState; } public void setState(String s){ myState = s; }}
2、在其它兩個Activity中分別調用
package activity.com;import android.app.Activity;import android.content.Intent;import android.os.Bundle;import android.util.Log;import android.view.View;import android.widget.Button;import android.widget.TextView;public class FirstActivity extends Activity {private TextView myTextView = null;private Button myButton = null; MyApp myApp; @Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.first);myTextView = (TextView) findViewById(R.id.myTextView);myTextView.setText("This is first TextView");myButton = (Button) findViewById(R.id.myButton);myButton.setText("First Button");myButton.setOnClickListener(new myOnClickListener());myApp=(MyApp) getApplication();}class myOnClickListener implements View.OnClickListener {@Overridepublic void onClick(View v) {String state = myApp.getState();Log.d("TEMP", "First擷取資料:"+state);myApp.setState("First");Log.d("TEMP", "First更改資料為資料:"+"First");Intent intent = new Intent();intent.setClass(FirstActivity.this, SecondActivity.class);FirstActivity.this.startActivity(intent);}}}
package activity.com;import android.app.Activity;import android.os.Bundle;import android.util.Log;import android.view.View;import android.widget.Button;import android.widget.TextView;public class SecondActivity extends Activity{private Button myButton2 = null;private TextView myTextView2 = null;MyApp myApp;@Overridepublic void onCreate(Bundle savedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.second);System.out.println("2->1");myTextView2 =(TextView)findViewById(R.id.myTextView2);myTextView2.setText("This is second TextView");System.out.println("2->2");myButton2 = (Button)findViewById(R.id.myButton2) ;myButton2.setText("Second Button");myButton2.setOnClickListener(new myOnClickListener());System.out.println("2->3");myApp=(MyApp) getApplication();}class myOnClickListener implements View.OnClickListener {@Overridepublic void onClick(View v) {String state = myApp.getState();Log.d("TEMP", "Second擷取資料:"+state);myApp.setState("Second");Log.d("TEMP", "Second更改資料為資料:"+"Second");}}}
3、AndroidManifest.xml中的設定:
在application的name標籤中添加MyApplication,如下:
<application android:icon="@drawable/icon" android:label="@string/app_name" android:name=".MyApp">
4、變數在一個Activity中改變後,在其它Activity中可以擷取改變後的值
04-25 04:32:23.361: DEBUG/TEMP(1130): First擷取資料:start
04-25 04:32:23.361: DEBUG/TEMP(1130): First更改資料為資料:First
04-25 04:32:30.891: DEBUG/TEMP(1130): Second擷取資料:First
04-25 04:32:30.891: DEBUG/TEMP(1130): Second更改資料為資料:Second
04-25 04:32:36.743: DEBUG/TEMP(1130): First擷取資料:Second
04-25 04:32:36.743: DEBUG/TEMP(1130): First更改資料為資料:First
04-25 04:32:39.883: DEBUG/TEMP(1130): Second擷取資料:First
04-25 04:32:39.883: DEBUG/TEMP(1130): Second更改資料為資料:Second
操作
代碼:http://download.csdn.net/detail/love254443233/4254731