Android Activity全局数据共享

package com.example.metrox.l13;

import android.app.Application;

/**
* Created by MetroX on 2016/6/13.
*/
public class App extends Application {
private String textDate = "Default";

public String getTextDate() {
return textDate;
}

public void setTextDate(String textDate) {
this.textDate = textDate;
}
}

package com.example.metrox.l13;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

TextView tv;
EditText et ;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main1);
tv = (TextView) findViewById(R.id.textView);
et = (EditText)findViewById(R.id.editText);
tv.setText("ShareData: " + ((App)getApplicationContext()).getTextDate());
findViewById(R.id.btnSave).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
((App)getApplicationContext()).setTextDate(et.getText().toString());
tv.setText("ShareData: " + et.getText().toString());
}
});
}
}

package com.example.metrox.l13;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;

/**
* Created by MetroX on 2016/6/13.
*/
public class Main2 extends Activity {
TextView tv;
EditText et ;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main2);
tv = (TextView) findViewById(R.id.textView);
et = (EditText)findViewById(R.id.editText);
tv.setText("ShareData: " + ((App)getApplicationContext()).getTextDate());
findViewById(R.id.btnSave).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
((App)getApplicationContext()).setTextDate(et.getText().toString());
tv.setText("ShareData: " + et.getText().toString());
}
});
}
}

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.metrox.l13">

<application
android:name=".App"
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity" android:label="Main1">
<intent-filter>
<action android:name="android.intent.action.MAIN" />

<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".Main2" android:label="Main2">
<intent-filter>
<category android:name="android.intent.category.LAUNCHER"></category>
<action android:name="android.intent.action.MAIN"></action>
</intent-filter>
</activity>
</application>

</manifest>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">

<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="New Text"
android:id="@+id/textView"
android:textSize="20dp" />

<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/editText" />

<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="保存"
android:id="@+id/btnSave" />
</LinearLayout>