Simple Android Application for Native Calculator 

Aim:

        To develop a Simple Android Application for Native Calculator.

Procedure:

Creating a New project:

• Open Android Stdio and then click on File -> New -> New project.

• Then type the Application name as “ex.no.3″ and click Next. 

• Then select the Minimum SDK as shown below and click Next.

• Then select the Empty Activity and click Next. 

• Finally click Finish.

• It will take some time to build and load the project.
• After completion it will look as given below.

Designing layout for the Android Application:

• Click on app -> res -> layout -> activity_main.xml.

• Now click on Text as shown below.

• Then delete the code which is there and type the code as given below.

Code for Activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent" android:layout_margin="20dp"> <LinearLayout android:id="@+id/linearLayout1" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_margin="20dp"> <EditText android:id="@+id/editText1" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_weight="1" android:inputType="numberDecimal" android:textSize="20sp" /> <EditText android:id="@+id/editText2" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_weight="1" android:inputType="numberDecimal" android:textSize="20sp" /> </LinearLayout> <LinearLayout android:id="@+id/linearLayout2" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_margin="20dp"> <Button android:id="@+id/Add" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_weight="1" android:text="+" android:textSize="30sp"/> <Button android:id="@+id/Sub" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_weight="1" android:text="-" android:textSize="30sp"/> <Button android:id="@+id/Mul" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_weight="1" android:text="*" android:textSize="30sp"/> <Button android:id="@+id/Div" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_weight="1" android:text="/" android:textSize="30sp"/> </LinearLayout> <TextView android:id="@+id/textView" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_marginTop="50dp" android:text="Answer is" android:textSize="30sp" android:gravity="center"/> </LinearLayout>

• Now click on Design and your application will look as given below.

• So now the designing part is completed.

Java Coding for the Android Application:

• Click on app -> java -> com.example.exno3 -> MainActivity.

• Then delete the code which is there and type the code as given below.

Code for MainActivity.java:

package com.example.devang.exno3; import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.text.TextUtils;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView; public class MainActivity extends AppCompatActivity implements OnClickListener
{ //Defining the Views EditText Num1; EditText Num2; Button Add; Button Sub; Button Mul; Button Div; TextView Result; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); //Referring the Views Num1 = (EditText) findViewById(R.id.editText1); Num2 = (EditText) findViewById(R.id.editText2); Add = (Button) findViewById(R.id.Add); Sub = (Button) findViewById(R.id.Sub); Mul = (Button) findViewById(R.id.Mul); Div = (Button) findViewById(R.id.Div); Result = (TextView) findViewById(R.id.textView); // set a listener Add.setOnClickListener(this); Sub.setOnClickListener(this); Mul.setOnClickListener(this); Div.setOnClickListener(this); } @Override public void onClick (View v) { float num1 = 0; float num2 = 0; float result = 0; String oper = ""; // check if the fields are empty if (TextUtils.isEmpty(Num1.getText().toString()) || TextUtils.isEmpty(Num2.getText().toString())) return; // read EditText and fill variables with numbers num1 = Float.parseFloat(Num1.getText().toString()); num2 = Float.parseFloat(Num2.getText().toString()); // defines the button that has been clicked and performs the corresponding operation // write operation into oper, we will use it later for output switch (v.getId()) { case R.id.Add: oper = "+"; result = num1 + num2; break; case R.id.Sub: oper = "-"; result = num1 - num2; break; case R.id.Mul: oper = "*"; result = num1 * num2; break; case R.id.Div: oper = "/"; result = num1 / num2; break; default: break; } // form the output line Result.setText(num1 + " " + oper + " " + num2 + " = " + result); }
}

• So now the Coding part is also completed.
• Now run the application to see the output.

Output:

                
 
                

Result:

              Thus a Simple Android Application for Native Calculator is developed and executed successfully.