1. mainActivity

package com.example.expintent;

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 {

	private Button btn_open;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
				
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		btn_open=(Button)findViewById(R.id.btn_open);
		btn_open.setOnClickListener(new OnClickListener() {
			
			public void onClick(View v) {
				// TODO Auto-generated method stub
				Intent intent=new Intent();
				intent.setClass(MainActivity.this,newActivity.class);
				startActivity(intent);
			}
		});
	}



}

 

<LinearLayout 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:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/hello_world" />
    <Button
        android:id="@+id/btn_open"
        android:layout_width="match_parent"
        android:layout_height="50dp"   
        android:text="@string/btn" />

</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.expintent"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="18" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.expintent.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="newActivity">
           	 	</activity>
    </application>

</manifest>

2.newActivity

package com.example.expintent;

import android.app.Activity;
import android.os.Bundle;

public class newActivity extends Activity {
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		// TODO Auto-generated method stub
		super.onCreate(savedInstanceState);
		setContentView(R.layout.newactivity);
	}

}