example about button clicklistner

//step1:
drag&drop the button component into  the layout.
//step2:
bind the components with id
 Button b=(Button)findviewByID(R.id.button1);
//step3:
provide event handler action for button.
b.setonclicklistner(this);
//example:when press the button 
toast.maketest(this,"hi i am vijay",30).show();




package com.myfirstlenovoapp;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends Activity implements OnClickListener {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        Button b=(Button)findViewById(R.id.button1);
        b.setOnClickListener(this);
    }


@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
Toast.makeText(this,"hi i am vijay", 30).show();
    }
}

write the below code in main.xml page :

<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"

    android:background="#ffc0cb" >

    <Button

        android:id="@+id/button1"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_alignParentLeft="true"

        android:layout_alignParentTop="true"

        android:layout_marginLeft="102dp"

        android:layout_marginTop="90dp"

        android:text="@string/hi" />

</RelativeLayout>

  following figure illustrates the answer: