STEP 1:: 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"
    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" >

    <EditText
        android:id="@+id/txt1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="42dp"
        android:ems="10" />

    <Button
        android:id="@+id/bnt1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/txt1"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="38dp"
        android:text="clickme" />

</RelativeLayout>

STEP 2:: MainActivity.java

package com.example.athome;

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.EditText;
import android.widget.Toast;

public class MainActivity extends Activity implements OnClickListener{
Button bnt1;
EditText txt1;
String str;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        txt1=(EditText) findViewById(R.id.txt1);
        bnt1=(Button)findViewById(R.id.bnt1);
        str=txt1.getText().toString();
        bnt1.setOnClickListener(this);
        
        
    } 


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }


@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if (v.getId()==R.id.bnt1) 
{
Toast.makeText(this,"hie "+txt1.getText(), Toast.LENGTH_LONG).show();
}

}
    
}