Simple calculator program in android

Hi everyone.Here I am going to put a simple calculator program in Android.

Please find the required files
1.MainActivity.java
2. activity_main.xml (Layoutfile)
3. String.xml

1. MainActivity.java

/* MainActivity starts here */
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends Activity {

/* Variable declaration starts here */
Button plusButton ;
     Button minusButton;
Button mulButton ;
Button divideButton;
EditText number1EditText ;
EditText number2EditText;
TextView result; 
 
/* End of variable declaration*/

/*Please don't give any code inside these two function */
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
variable_defenition();
call_to_main_function();

}

@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;
}

/* End of function */

public void variable_defenition(){
/* Variable declaration starts here */

plusButton = (Button) findViewById(R.id.plusbutton);
minusButton = (Button) findViewById(R.id.minusbutton);
mulButton = (Button) findViewById(R.id.multiplybutton);
divideButton = (Button) findViewById(R.id.dividebutton);
number1EditText = (EditText) findViewById(R.id.edittextnumber1);
number2EditText = (EditText) findViewById(R.id.edittextnumber2);
result = (TextView) findViewById(R.id.textResult); 
 
/* End of variable declaration*/
}

public void call_to_main_function(){

/*Code for Addition */

plusButton.setOnClickListener(new View.OnClickListener() {
          public void onClick(View v) {
          String str1 = number1EditText.getText().toString();   
          String str2 = number2EditText.getText().toString(); 
          Float num1=Float.parseFloat(str1);
          Float num2=Float.parseFloat(str2);
          Float interresult;
          
          interresult = num1 + num2;
          result.setText(interresult.toString());
          } });

/* Code for addition ends here*/


/*Code for Subtraction */
minusButton.setOnClickListener(new View.OnClickListener() {
          public void onClick(View v) {
          String str1 = number1EditText.getText().toString();   
          String str2 = number2EditText.getText().toString(); 
          Float num1=Float.parseFloat(str1);
          Float num2=Float.parseFloat(str2);
                   Float interresult;
          
          interresult = num1 - num2;
          result.setText(interresult.toString() );
          
          
          } });

/* Code for Subtraction ends here*/

/*Code for Multiplication */
mulButton.setOnClickListener(new View.OnClickListener() {
          public void onClick(View v) {
          String str1 = number1EditText.getText().toString();   
          String str2 = number2EditText.getText().toString(); 
          Float num1=Float.parseFloat(str1);
          Float num2=Float.parseFloat(str2);
                   Float interresult;
          
          interresult = num1 * num2;
          result.setText(interresult.toString());
          
          
          } });

/* Code for Multiplication ends here*/


/*Code for Division */
divideButton.setOnClickListener(new View.OnClickListener() {
          public void onClick(View v) {
          String str1 = number1EditText.getText().toString();   
          String str2 = number2EditText.getText().toString(); 
          Float num1=Float.parseFloat(str1);
          Float num2=Float.parseFloat(str2);
                   Float interresult;
          
                   if(num2 == 0)
                  result.setText("Cannot divide by 0");
                   else {
                   interresult = num1 / num2;
          result.setText(interresult.toString());
                   }
          
          
          } });

/* Code for Division ends here*/

}//End of call_to_main_function

}

/* MainActivity ends here */


2. activity_main.xml
<!-- Layout starts here-->
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:layout_width="fill_parent"
   android:layout_height="fill_parent"
   android:orientation="vertical" >
   
    <LinearLayout
   android:layout_width="fill_parent"
   android:layout_height="wrap_content"
   android:orientation="vertical" >  
    
    <TextView android:id="@+id/textNumber1"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="@string/enumber1" />
    <EditText
        android:id="@+id/edittextnumber1"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:ems="10"
        android:text="@string/number1" android:inputType="number" />
    
    
     <TextView android:id="@+id/textNumber2"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="@string/enumber2" />
      <EditText
        android:id="@+id/edittextnumber2"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:ems="10"
        android:text="@string/number2" android:inputType="number" />
    
     
     </LinearLayout>
     
    <LinearLayout 
  android:layout_width="fill_parent"
  android:layout_height="wrap_content"
   android:orientation="horizontal" >   
   
  <Button
    android:id="@+id/plusbutton"    
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/plus"
    android:onClick="sendMessage" />
  <Button
       android:id="@+id/minusbutton"  
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/minus"
    android:onClick="sendMessage" />
    
    <Button
      android:id="@+id/multiplybutton"    
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
     android:text="@string/multiply"
    android:onClick="sendMessage" />
    
     <Button
      android:id="@+id/dividebutton" 
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/divide"
    android:onClick="sendMessage" />
    

</LinearLayout >
    
     
<LinearLayout 
  android:layout_width="fill_parent"
  android:layout_height="wrap_content"
   android:orientation="vertical" >   
   
 <TextView android:id="@+id/textResultLabel"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="@string/calcResult"
       />


  <TextView android:id="@+id/textResult"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="" />

</LinearLayout >


<!-- End of Linear layout -->

</LinearLayout>

<!-- Layout ends here-->

3. String.xml

<!-- Strings starts here-->

<?xml version="1.0" encoding="utf-8"?>

<resources>

    <string name="app_name">Calculator</string>

    <string name="action_settings">Settings</string>

    <string name="hello_world">Hello world!</string>

    <string name="calcResult">Result </string>

    <string name="number1"></string>

    <string name="number2"></string>

    <string name="plus">+</string>

<string name="minus">-</string>

<string name="multiply">*</string>

<string name="divide">/</string>

<string name="enumber1">Enter Number 1 </string>

    <string name="enumber2">Enter Number 2 </string>

</resources>

<!-- Strings end here-->