<?xml version="1.0" encoding="utf-8"?>

<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"

    android:paddingBottom="@dimen/activity_vertical_margin"

    android:paddingLeft="@dimen/activity_horizontal_margin"

    android:paddingRight="@dimen/activity_horizontal_margin"

    android:paddingTop="@dimen/activity_vertical_margin"

    tools:context="com.example.app.androidvaluespass.MainActivity">

    <Button

        android:id="@+id/btnSubmit"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:text="值传递"/>

</RelativeLayout>

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="match_parent"

    android:layout_height="match_parent">

  <EditText

      android:layout_width="wrap_content"

      android:layout_height="wrap_content"

      android:id="@+id/Msg"/>

</LinearLayout>

package com.example.app.androidvaluespass;

import android.app.Activity;

import android.content.Intent;

import android.os.Bundle;

import android.view.View;

import android.widget.Button;

public class MainActivity extends Activity {

    private Button btn;

    private MyApp myApp;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        btn = (Button)this.findViewById(R.id.btnSubmit);

        btn.setOnClickListener(new View.OnClickListener() {

            @Override

            public void onClick(View view) {

                myApp = (MyApp)getApplication();

                myApp.setName("赵信!");//修改后的名称

                Intent intent = new Intent(MainActivity.this,ValuesActivity.class);

                startActivity(intent);

            }

        });

    }

}

package com.example.app.androidvaluespass;

import android.app.Application;

/**

 * Created by honghong on 2016/6/18.

 */

public class MyApp extends Application {

    public String name;

    public String getName() {

        return name;

    }

    public void setName(String name) {

        this.name = name;

    }

    @Override

    public void onCreate() {

        super.onCreate();

        setName("张三");

    }

}

package com.example.app.androidvaluespass;

import android.app.Activity;

import android.os.Bundle;

import android.widget.TextView;

/**

 * Created by honghong on 2016/6/18.

 */

public class ValuesActivity extends Activity {

    private MyApp myApp;

    private TextView editText;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.values);

        editText = (TextView)this.findViewById(R.id.Msg);

        myApp = (MyApp)getApplication();

        editText.setText(myApp.getName());

    }

}

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="com.example.app.androidvaluespass">

    <application

        android:name=".MyApp" // ← 继承Application类的名称，这个一定要对应。

        android:allowBackup="true"

        android:icon="@mipmap/ic_launcher"

        android:label="@string/app_name"

        android:supportsRtl="true"

        android:theme="@style/AppTheme">

        <activity android:name=".MainActivity">

            <intent-filter>

                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />

            </intent-filter>

        </activity>

        <activity android:name=".ValuesActivity"></activity>  // 这个类调用Application类ValuesActivity

    </application>

</manifest>