Ex.No:3. Develop a native calculator application.

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.