how to Add numbers in EditText and Diplay on TextView in Android

activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:orientation="vertical"
  android:background="#373">

<TextView 
  android:id="@+id/textView1"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="Enter First Value:"
  android:textSize="25sp" />
 
<EditText
  android:id="@+id/editText1"
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:ems="10"
  android:inputType="numberDecimal">
 </EditText>
 
<TextView
  android:id="@+id/textView2" 
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="Enter Second Value:"
  android:textSize="25sp" />
 
<EditText
  android:id="@+id/editText2"
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:inputType="numberDecimal"
  android:ems="10" />

<TextView
  android:id="@+id/result"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:textSize="30sp" />
 
<Button
  android:id="@+id/button1"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="Add Values"
  android:onClick="add"
/> 
</LinearLayout>

MainActivity.java

import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import android.app.Activity;

public class MainActivity extends Activity {
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
 }

 
 
 public void add(View v)
 {
 //initialize objects
 TextView result=(TextView)findViewById(R.id.result);
 EditText et1=(EditText)findViewById(R.id.editText1);
 EditText et2=(EditText)findViewById(R.id.editText2);


 // get text from edit text boxes and convert into double
 double a=Double.parseDouble(String.valueOf(et1.getText()));
 double b=Double.parseDouble(String.valueOf(et2.getText()));
 
 //add them
 double c=a+b;

 //display addition on TextView
 result.setText("Add:"+c);
 
 }
}