Android Passing primitives between Activities

We can pass the data between activities in forward and backward directions means

first activity =====> second activity

second activity =====> first activity

Make a project with name AndroidPassingPrimitives

MainActivity.java


package com.jitesh.androidpassingprimitives;

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

public class MainActivity extends Activity {
private static final int PLAY_GAME = 1010;

private TextView tv;
private int meaningOfLife = 786;
private String userName = "Upadhyay Jitesh";

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tv = (TextView) findViewById(R.id.startscreen_text);
// display initial values
tv.setText(userName + ":" + meaningOfLife);
// setup button listener
Button startButton = (Button) findViewById(R.id.play_game);
startButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
startGame();
}
});
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == PLAY_GAME && resultCode == RESULT_OK) {
meaningOfLife = data.getExtras().getInt("returnInt");
userName = data.getExtras().getString("returnStr");
// show it has changed
tv.setText(userName + ":" + meaningOfLife);
}
super.onActivityResult(requestCode, resultCode, data);
}

private void startGame() {
Intent launchGame = new Intent(this, PlayGame.class);
// passing information to launched activity
launchGame.putExtra("meaningOfLife", meaningOfLife);
launchGame.putExtra("userName", userName);
startActivityForResult(launchGame, PLAY_GAME);
}
}

PlayGame.java


package com.jitesh.androidpassingprimitives;

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

public class PlayGame extends Activity {
private TextView tv2;
int answer;
String author;

public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.game);
tv2 = (TextView) findViewById(R.id.game_text);
// reading information passed to this activity
// Get the intent that started this activity
Intent i = getIntent();
// returns -1 if not initialized by calling activity
answer = i.getIntExtra("meaningOfLife", -1);
// returns [] if not initialized by calling activity
author = i.getStringExtra("userName");
tv2.setText(author + ":" + answer);
// change values for an example of return
answer = answer - 41;
author = author + " Jr.";
// setup button listener
Button startButton = (Button) findViewById(R.id.end_game);
startButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
// return information to calling activity
Intent i = getIntent();
i.putExtra("returnInt", answer);
i.putExtra("returnStr", author);
setResult(RESULT_OK, i);
finish();
}
});
}
}

activity_main.xml


<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" >

    <TextView
        android:id="@+id/startscreen_text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:text="@string/hello_world"
        tools:context=".MainActivity" />

    <Button
        android:id="@+id/play_game"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_above="@+id/startscreen_text"
        android:layout_alignRight="@+id/startscreen_text"
        android:layout_marginBottom="55dp"
        android:layout_marginRight="34dp"
        android:text="Button" />

</RelativeLayout>

game.xml


<?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"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/game_text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

    <Button
        android:id="@+id/end_game"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_above="@+id/startscreen_text"
        android:layout_alignRight="@+id/startscreen_text"
        android:layout_marginBottom="55dp"
        android:layout_marginRight="34dp"
        android:text="Button" />

</LinearLayout>


manifest file

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

    package="com.jitesh.androidpassingprimitives"

    android:versionCode="1"

    android:versionName="1.0" >

    <uses-sdk

        android:minSdkVersion="8"

        android:targetSdkVersion="15" />

    <application

        android:icon="@drawable/ic_launcher"

        android:label="@string/app_name"

        android:theme="@style/AppTheme" >

        <activity

            android:name=".MainActivity"

            android:label="@string/title_activity_main" >

            <intent-filter>

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

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

            </intent-filter>

        </activity>

          <activity android:name="PlayGame"></activity>

    </application>

</manifest>

you can download the source code from AndroidPassingPrimitives