Simple calculator program to add and subtract 2 numbers: Android tutorial

Program description:

This is a simple android calculator program with 3 edit text boxes, with 2 buttons.
User will enter two numbers in first and second edit text, and click the button.
button 1 is to add two numbers, and button 2 is to subtract the numbers.

             First Activity                         First Activity( after entering numbers)

          

             
     First Activity( click add)                                 First Activity( click sub)

           

First Activity

package com.example.b15_calc;

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;

public class MainActivity extends Activity {
 //step1 : create all the variables.
 EditText et1, et2, et3;
 Button b1, b2;
 
 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 
 //step2 : get all the views from xml file.
 et1 = (EditText) findViewById(R.id.editText1);
 et2 = (EditText) findViewById(R.id.editText2);
 et3 = (EditText) findViewById(R.id.editText3);

 b1 = (Button) findViewById(R.id.button1);
 b2 = (Button) findViewById(R.id.button2);
 
 //step3 : write add functionality.
 b1.setOnClickListener(new OnClickListener() {
 @Override
 public void onClick(View v) {
 String f = et1.getText().toString();
 int i = Integer.parseInt(f);
 String s = et2.getText().toString();
 int j = Integer.parseInt(s);
 
 Integer result = i+j;
 String res = result.toString();
 et3.setText(res);
 }
 });
 b2.setOnClickListener(new OnClickListener() {
 @Override
 public void onClick(View v) {
 String f = et1.getText().toString();
 int i = Integer.parseInt(f);
 String s = et2.getText().toString();
 int j = Integer.parseInt(s);
 
 Integer result = i-j;
 String res = result.toString();
 et3.setText(res);
 }
 });
 
 }

 @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;
 }

}

xml layout file for First Activity 

File name: activity_main.xml

  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:id="@+id/editText1" 
 android:layout_width="wrap_content" 
 android:layout_height="wrap_content" 
 android:layout_alignParentTop="true" 
 android:layout_centerHorizontal="true" 
 android:layout_marginTop="24dp" 
 android:ems="10" 
 android:inputType="textNoSuggestions"/> 
  android:id="@+id/editText2" 
 android:layout_width="wrap_content" 
 android:layout_height="wrap_content" 
 android:layout_alignLeft="@+id/editText1" 
 android:layout_below="@+id/editText1" 
 android:ems="10" /> 
 

Download complete code : Click to download

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Tags : android calculator program, android tutorial, calculator