Calculator Program using Android

This Android Program lets you create an Activity to create a Toast in an Application.

Here is source code of the Program to create an Activity to create a Toast in an Application using Java. The program is successfully compiled and run on a Windows system using Eclipse Ide. The program output is also shown below.

Main Activity

 
package com.example.calculator;
 
import android.R.color;
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.TextView;
import android.widget.Toast;
 
public class MainActivity extends Activity implements OnClickListener {
 
    TextView disp, res;
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        disp = (TextView) findViewById(R.id.textView1);
        res = (TextView) findViewById(R.id.textView2);
        Button add = (Button) findViewById(R.id.add);
        Button mul = (Button) findViewById(R.id.mul);
        Button divide = (Button) findViewById(R.id.divide);
        Button sub = (Button) findViewById(R.id.sub);
        Button log = (Button) findViewById(R.id.log);
        Button clear = (Button) findViewById(R.id.clear);
        Button calc = (Button) findViewById(R.id.calculate);
        Button change = (Button) findViewById(R.id.color);
 
        add.setOnClickListener(this);
        mul.setOnClickListener(this);
        divide.setOnClickListener(this);
        sub.setOnClickListener(this);
        log.setOnClickListener(this);
        clear.setOnClickListener(this);
        calc.setOnClickListener(this);
        change.setOnClickListener(this);
 
    }
 
    @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;
    }
 
    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        float result = 0, num1, num2;
        Toast var;
        switch (v.getId()) {
        case R.id.add:
            String str =(String) disp.getText();
            num1 = Integer.parseInt(str);
            disp.setText("");
            var = Toast.makeText(MainActivity.this, "Enter other number",
                    Toast.LENGTH_SHORT);
            var.show();
            str=(String) disp.getText();
            num2 = Integer.parseInt(str);
            result = num1 + num2;
            break;
 
        case R.id.sub:
            num1 = Integer.parseInt((String) disp.getText());
            disp.setText("");
            var = Toast.makeText(MainActivity.this, "Enter other number",
                    Toast.LENGTH_SHORT);
            var.show();
            num2 = Integer.parseInt((String) disp.getText());
            result = num1 - num2;
            break;
        case R.id.mul:
            num1 = Integer.parseInt((String) disp.getText());
            disp.setText("");
            var = Toast.makeText(MainActivity.this, "Enter other number",
                    Toast.LENGTH_SHORT);
            var.show();
            num2 = Integer.parseInt((String) disp.getText());
            result = num1 * num2;
            break;
        case R.id.divide:
            num1 = Integer.parseInt((String) disp.getText());
            disp.setText("");
            var = Toast.makeText(MainActivity.this, "Enter other number",
                    Toast.LENGTH_SHORT);
            var.show();
            num2 = Integer.parseInt((String) disp.getText());
            result = num1 / num2;
            break;
        case R.id.log:
            num1 = Integer.parseInt((String) disp.getText());
            result = (float) Math.log(num1);
            break;
        case R.id.clear:
            disp.setText("");
            res.setText("");
            break;
        case R.id.color:
            int rand = (int) ((Math.random() * 10) % 3);
            Button b1 = (Button) findViewById(R.id.add);
            Button b2 = (Button) findViewById(R.id.mul);
            Button b3 = (Button) findViewById(R.id.divide);
            Button b4 = (Button) findViewById(R.id.sub);
            Button b5 = (Button) findViewById(R.id.log);
            Button b6 = (Button) findViewById(R.id.clear);
            Button b7 = (Button) findViewById(R.id.calculate);
            Button b8 = (Button) findViewById(R.id.color);
 
            rand =2;
            switch (rand) {
            case 0:
                b1.setTextColor(color.holo_blue_bright);
                b2.setTextColor(color.holo_blue_bright);
                b3.setTextColor(color.holo_blue_bright);
                b4.setTextColor(color.holo_blue_bright);
                b5.setTextColor(color.holo_blue_bright);
                b6.setTextColor(color.holo_blue_bright);
                b7.setTextColor(color.holo_blue_bright);
                b8.setTextColor(color.holo_blue_bright);
                break;
            case 1:
                b1.setTextColor(color.holo_green_dark);
                b2.setTextColor(color.holo_green_dark);
                b3.setTextColor(color.holo_green_dark);
                b4.setTextColor(color.holo_green_dark);
                b5.setTextColor(color.holo_green_dark);
                b6.setTextColor(color.holo_green_dark);
                b7.setTextColor(color.holo_green_dark);
                b8.setTextColor(color.holo_green_dark);
                break;
            case 2:
                b1.setTextColor(color.holo_red_dark);
                b2.setTextColor(color.holo_red_dark);
                b3.setTextColor(color.holo_red_dark);
                b4.setTextColor(color.holo_red_dark);
                b5.setTextColor(color.holo_red_dark);
                b6.setTextColor(color.holo_red_dark);
                b7.setTextColor(color.holo_red_dark);
                b8.setTextColor(color.holo_red_dark);
                break;
 
            default:
                b1.setTextColor(color.black);
                b2.setTextColor(color.black);
                b3.setTextColor(color.black);
                b4.setTextColor(color.black);
                b5.setTextColor(color.black);
                b6.setTextColor(color.black);
                b7.setTextColor(color.black);
                b8.setTextColor(color.black);
                break;
            }
 
            break;
        case R.id.calculate:
            res.setText(Float.toString(result));
            break;
        }
    }
 
}

Xml

 
<TableLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:columnCount="2"
    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" >
 
    <EditText
        android:id="@+id/textView1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="0"
        android:textSize="30sp" />
 
    <TextView
        android:id="@+id/textView2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="TextView"
        android:textSize="30sp" />
 
    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="40dp"
        android:layout_weight="0.29" >
 
        <Button
            android:id="@+id/add"
            android:layout_width="80dp"
            android:layout_height="wrap_content"
            android:text="+"
            android:textSize="20dp" >
        </Button>
 
        <Button
            android:id="@+id/sub"
            android:layout_width="80dp"
            android:layout_height="wrap_content"
            android:layout_alignBaseline="@+id/button1"
            android:layout_alignBottom="@+id/button1"
            android:layout_centerHorizontal="true"
            android:text="-" />
 
        <Button
            android:id="@+id/mul"
            android:layout_width="80dp"
            android:layout_height="wrap_content"
            android:layout_alignBaseline="@+id/button2"
            android:layout_alignBottom="@+id/button2"
            android:layout_alignParentRight="true"
            android:text="X" />
 
        <Button
            android:id="@+id/calculate"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_alignParentBottom="true"
            android:layout_alignParentRight="true"
            android:layout_marginBottom="64dp"
            android:textAlignment="center"
            android:text="Calculate" />
 
        <Button
            android:id="@+id/color"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_alignParentBottom="true"
            android:layout_alignParentRight="true"
            android:text="ChangeColor" 
            android:textAlignment="center"/>
 
        <Button
            android:id="@+id/divide"
            android:layout_width="80dp"
            android:layout_height="wrap_content"
            android:layout_alignParentLeft="true"
            android:layout_below="@+id/add"
            android:layout_marginTop="47dp"
            android:text="/" />
 
        <Button
            android:id="@+id/log"
            android:layout_width="80dp"
            android:layout_height="wrap_content"
            android:layout_alignBaseline="@+id/divide"
            android:layout_alignBottom="@+id/divide"
            android:layout_alignLeft="@+id/sub"
            android:text="log" />
 
        <Button
            android:id="@+id/clear"
            android:layout_width="80dp"
            android:layout_height="wrap_content"
            android:layout_alignBaseline="@+id/log"
            android:layout_alignBottom="@+id/log"
            android:layout_alignParentRight="true"
            android:text="C" />
 
    </RelativeLayout>
 
</TableLayout>

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