ex4_2_subactivity_setuser

//AndroidManifest.xml

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

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        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=".SUBACTIVITY1">

        </activity>
    </application>

</manifest>

//MainActivity.java

package com.example.ml.myapplication;

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

public class MainActivity extends Activity {
    private static final int SUBACTIVITY1 = 1;
    //private static final int SUBACTIVITY2 = 2;

    TextView ed1;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ed1 = (TextView) findViewById(R.id.et1);
        final Button btn1 = (Button)findViewById(R.id.btn1);
        btn1.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(MainActivity.this,SUBACTIVITY1.class);
                startActivityForResult(intent,SUBACTIVITY1);
            }
        });


    }
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        switch(requestCode){
            case SUBACTIVITY1:
                if (resultCode == RESULT_OK){
                    Uri uriData = data.getData();
                    ed1.setText(uriData.toString());
                }
                break;
        }
    }
}

//SUBACTIVITY1.java

package com.example.ml.myapplication;

import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

/**
 * Created by Administrator on 2018/6/19.
 */

@SuppressLint("Registered")
public class SUBACTIVITY1 extends Activity {
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.subactivity1);

        final EditText editText = (EditText)findViewById(R.id.et2);
        Button btnOK = (Button)findViewById(R.id.btn2);


        btnOK.setOnClickListener(new View.OnClickListener(){
            public void onClick(View view){
                String uriString = editText.getText().toString();
                Uri data = Uri.parse(uriString);

                Intent result = new Intent(null, data);

                setResult(RESULT_OK, result);
                finish();
            }
        });
    }

}

//activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.ml.myapplication.MainActivity">
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        android:gravity="center_vertical|center">
        <Button
            android:id="@+id/btn1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="login"/>
        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal">
            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="user:"/>
            <TextView
                android:id="@+id/et1"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text=""/>

        </LinearLayout>


    </LinearLayout>
</android.support.constraint.ConstraintLayout>

//subactivity.xml

<?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"
    android:gravity="center_vertical|center">
    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">
        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Username:"/>
        <EditText
            android:id="@+id/et2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />

    </LinearLayout>
    <Button
        android:id="@+id/btn2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="backward"/>


</LinearLayout>