First Case of Intent in Android

Intent

An intent is an abstract description of an operation to be performed. In simple words, we can say that intent is basically used to notify the Android system about the occurrence of an event.

Procedure

Use the following procedure:

Start Eclipse IDE.
Create a new project.
Create two Java files, one is MainActivity.java and the other is a.java.
Create two XML files, one is activity_main.xml file and the second is other.xml for layout design.
In the first case of intent, we add an activity with an intent filter in the manifest file.
For instance
1. <activity
2. android:name="A"
3. android:label="@string/app_name" >
4. <intent-filter>
5. <action android:name="abhijeet" />
6. <category android:name="android.intent.category.DEFAULT" />
7. </intent-filter>
8. </activity>
Then look up the button by its id in the MainActivity.java file and declare a string in it.
Then in the onclick function declare an intent.

For example
1. public void onClick(View v) {
2. Intent i=new Intent(str);
3. startActivity(i);
4. }

The code is given below.

MainActivity.java

package com.example.intentistcaseeeee;
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
public class MainActivity extends Activity implements OnClickListener {
Button b1;
String str = "abhijeet";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
b1 = (Button) findViewById(R.id.button1);
b1.setOnClickListener(this);
}
public void onClick(View v) {
Intent i = new Intent(str);
startActivity(i);
}
}

<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=".MainActivity" >
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/hello_world" />
<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/textView1"
android:layout_marginTop="52dp"
android:layout_toRightOf="@+id/textView1"
android:text="Button" />
</RelativeLayout>

A.java

package com.example.intentistcaseeeee;
import android.app.Activity;
import android.os.Bundle;
public class A extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.other);
}
}

Other.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" >
<Spinner
android:id="@+id/spinner1"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<RadioButton
android:id="@+id/radioButton1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="RadioButton" />
<CheckBox
android:id="@+id/checkBox1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="CheckBox" />
</LinearLayout>

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest
xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.intentistcaseeeee"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name="A"
android:label="@string/app_name" >
<intent-filter>
<action android:name="abhijeet" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
</application>
</manifest>

Output

By clicking on the Button: