Android Simple Calculator

Simple Calculator example..
I created a simple calculator  Android application to understand basic functions in Android.
 
CalculatorActivity.java

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1. package codesstore.calculator;  
2.   
3. import android.app.Activity;  
4. import android.os.Bundle;  
5. import android.view.View;  
6. import android.view.View.OnClickListener;  
7. import android.widget.Button;  
8. import android.widget.EditText;  
9. import android.widget.TextView;  
10.   
11. public class CalculatorActivity extends Activity implements OnClickListener {  
12.     Button buttonPlus;  
13.     Button buttonMinus;  
14.     Button buttonDivide;  
15.     Button buttonMultiply;  
16.     Button buttonOk;  
17.     TextView textAnswer;  
18.     TextView textOperator;  
19.     EditText num1;  
20.     EditText num2;  
21.     double sum;  
22.   
23.     @Override  
24.     public void onCreate(Bundle savedInstanceState) {  
25.         super.onCreate(savedInstanceState);  
26.         setContentView(R.layout.main);  
27.   
28.         buttonMinus = (Button) findViewById(R.id.buttonMinus);  
29.         buttonPlus = (Button) findViewById(R.id.buttonPlus);  
30.         buttonDivide = (Button) findViewById(R.id.buttonDivide);  
31.         buttonMultiply = (Button) findViewById(R.id.buttonMultiply);  
32.         buttonOk = (Button) findViewById(R.id.buttonOk);  
33.         num1 = (EditText) findViewById(R.id.num1);  
34.         num2 = (EditText) findViewById(R.id.num2);  
35.         textAnswer = (TextView) findViewById(R.id.textAnswer);  
36.         textOperator = (TextView) findViewById(R.id.textOperator);  
37.           
38.         buttonOk.setOnClickListener(this);  
39.         buttonPlus.setOnClickListener(this);  
40.         buttonMinus.setOnClickListener(this);  
41.         buttonMultiply.setOnClickListener(this);  
42.         buttonDivide.setOnClickListener(this);  
43.   
44.     }  
45.   
46.     @Override  
47.     public void onClick(View src) {  
48.   
49.         switch (src.getId()) {  
50.         case R.id.buttonOk:  
51.             textAnswer.setText(String.valueOf(sum));  
52.             break;  
53.         case R.id.buttonPlus:  
54.             sum = Double.parseDouble(String.valueOf(num1.getText()))  
55.                     + Double.parseDouble(String.valueOf(num2.getText()));  
56.             textOperator.setText("+");  
57.             break;  
58.         case R.id.buttonMinus:  
59.             sum = Double.parseDouble(String.valueOf(num1.getText()))  
60.                     - Double.parseDouble(String.valueOf(num2.getText()));  
61.             textOperator.setText("-");  
62.             break;  
63.         case R.id.buttonMultiply:  
64.             sum = Double.parseDouble(String.valueOf(num1.getText()))  
65.                     * Double.parseDouble(String.valueOf(num2.getText()));  
66.             textOperator.setText("*");  
67.             break;  
68.         case R.id.buttonDivide:  
69.             sum = Double.parseDouble(String.valueOf(num1.getText()))  
70.                     / Double.parseDouble(String.valueOf(num2.getText()));  
71.             textOperator.setText("/");  
72.             break;  
73.         }  
74.   
75.     }  
76. }  

package codesstore.calculator;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class CalculatorActivity extends Activity implements OnClickListener {
    Button buttonPlus;
    Button buttonMinus;
    Button buttonDivide;
    Button buttonMultiply;
    Button buttonOk;
    TextView textAnswer;
    TextView textOperator;
    EditText num1;
    EditText num2;
    double sum;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        buttonMinus = (Button) findViewById(R.id.buttonMinus);
        buttonPlus = (Button) findViewById(R.id.buttonPlus);
        buttonDivide = (Button) findViewById(R.id.buttonDivide);
        buttonMultiply = (Button) findViewById(R.id.buttonMultiply);
        buttonOk = (Button) findViewById(R.id.buttonOk);
        num1 = (EditText) findViewById(R.id.num1);
        num2 = (EditText) findViewById(R.id.num2);
        textAnswer = (TextView) findViewById(R.id.textAnswer);
        textOperator = (TextView) findViewById(R.id.textOperator);
        
        buttonOk.setOnClickListener(this);
        buttonPlus.setOnClickListener(this);
        buttonMinus.setOnClickListener(this);
        buttonMultiply.setOnClickListener(this);
        buttonDivide.setOnClickListener(this);

    }

    @Override
    public void onClick(View src) {

        switch (src.getId()) {
        case R.id.buttonOk:
            textAnswer.setText(String.valueOf(sum));
            break;
        case R.id.buttonPlus:
            sum = Double.parseDouble(String.valueOf(num1.getText()))
                    + Double.parseDouble(String.valueOf(num2.getText()));
            textOperator.setText("+");
            break;
        case R.id.buttonMinus:
            sum = Double.parseDouble(String.valueOf(num1.getText()))
                    - Double.parseDouble(String.valueOf(num2.getText()));
            textOperator.setText("-");
            break;
        case R.id.buttonMultiply:
            sum = Double.parseDouble(String.valueOf(num1.getText()))
                    * Double.parseDouble(String.valueOf(num2.getText()));
            textOperator.setText("*");
            break;
        case R.id.buttonDivide:
            sum = Double.parseDouble(String.valueOf(num1.getText()))
                    / Double.parseDouble(String.valueOf(num2.getText()));
            textOperator.setText("/");
            break;
        }

    }
}

main.xml
Main xml is used to create user interface.

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1. <?xml version="1.0" encoding="utf-8"?>  
2. <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
3.     android:layout_width="fill_parent"  
4.     android:layout_height="fill_parent"  
5.     android:orientation="vertical" >  
6.   
7.     <TextView  
8.         android:layout_width="fill_parent"  
9.         android:layout_height="wrap_content"  
10.         android:text="@string/title" android:gravity="center" android:textSize="30dp" android:paddingTop="3dp" android:paddingBottom="10dp"/>  
11.   
12.   
13.     <LinearLayout  
14.         android:id="@+id/inputs"  
15.         android:layout_width="match_parent"  
16.         android:layout_height="wrap_content" >  
17.   
18.   
19.         <EditText  
20.             android:id="@+id/num1"  
21.             android:layout_width="wrap_content"  
22.             android:layout_height="wrap_content"  
23.             android:layout_weight="1" />  
24.   
25.   
26.   
27.         <TextView  
28.             android:id="@+id/textOperator"  
29.             android:layout_width="wrap_content"  
30.             android:layout_height="wrap_content"  
31.             android:layout_weight="1" android:gravity="center" android:textSize="25dp"/>  
32.   
33.   
34.   
35.         <EditText  
36.             android:id="@+id/num2"  
37.             android:layout_width="wrap_content"  
38.             android:layout_height="wrap_content"  
39.             android:layout_weight="1" >  
40.   
41.             <requestFocus />  
42.         </EditText>  
43.   
44.     </LinearLayout>  
45.   
46.   
47.     <LinearLayout  
48.         android:id="@+id/answerbox"  
49.         android:layout_width="match_parent"  
50.         android:layout_height="wrap_content" >  
51.   
52.   
53.   
54.         <TextView  
55.             android:id="@+id/textAnswer"  
56.             android:layout_width="wrap_content"  
57.             android:layout_height="wrap_content" android:layout_weight="1" android:textSize="25dp"/>  
58.   
59.     </LinearLayout>  
60.   
61.   
62.     <LinearLayout  
63.         android:id="@+id/buttons"  
64.         android:layout_width="match_parent"  
65.         android:layout_height="wrap_content" >  
66.   
67.         <Button  
68.             android:id="@+id/buttonPlus"  
69.             android:layout_width="wrap_content"  
70.             android:layout_height="wrap_content"  
71.             android:text="+" android:layout_weight="1"/>  
72.   
73.   
74.         <Button  
75.             android:id="@+id/buttonMinus"  
76.             android:layout_width="wrap_content"  
77.             android:layout_height="wrap_content"  
78.             android:text="-" android:layout_weight="1"/>  
79.   
80.   
81.         <Button  
82.             android:id="@+id/buttonDivide"  
83.             android:layout_width="wrap_content"  
84.             android:layout_height="wrap_content"  
85.             android:text="/" android:layout_weight="1"/>  
86.   
87.   
88.         <Button  
89.             android:id="@+id/buttonMultiply"  
90.             android:layout_width="wrap_content"  
91.             android:layout_height="wrap_content"  
92.             android:text="*" android:layout_weight="1"/>  
93.   
94.   
95.         <Button  
96.             android:id="@+id/buttonOk"  
97.             android:layout_width="wrap_content"  
98.             android:layout_height="wrap_content"  
99.             android:text="=" android:layout_weight="1"/>  
100.   
101.     </LinearLayout>  
102.   
103. </LinearLayout>v   

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/title" android:gravity="center" android:textSize="30dp" android:paddingTop="3dp" android:paddingBottom="10dp"/>


    <LinearLayout
        android:id="@+id/inputs"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >


        <EditText
            android:id="@+id/num1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1" />



        <TextView
            android:id="@+id/textOperator"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1" android:gravity="center" android:textSize="25dp"/>



        <EditText
            android:id="@+id/num2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1" >

            <requestFocus />
        </EditText>

    </LinearLayout>


    <LinearLayout
        android:id="@+id/answerbox"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >



        <TextView
            android:id="@+id/textAnswer"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" android:layout_weight="1" android:textSize="25dp"/>

    </LinearLayout>


    <LinearLayout
        android:id="@+id/buttons"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >

        <Button
            android:id="@+id/buttonPlus"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="+" android:layout_weight="1"/>


        <Button
            android:id="@+id/buttonMinus"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="-" android:layout_weight="1"/>


        <Button
            android:id="@+id/buttonDivide"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="/" android:layout_weight="1"/>


        <Button
            android:id="@+id/buttonMultiply"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="*" android:layout_weight="1"/>


        <Button
            android:id="@+id/buttonOk"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="=" android:layout_weight="1"/>

    </LinearLayout>

</LinearLayout>v 

strings.xml

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1. <?xml version="1.0" encoding="utf-8"?>  
2. <resources>  
3.   
4.     <string name="title">Simple Calculator</string>  
5.     <string name="app_name">Calculator</string>  
6.   
7. </resources><u><i><b>  
8. </b></i></u>  

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

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

</resources>

R.java
This is a file auto generated by android.

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1. /* AUTO-GENERATED FILE.  DO NOT MODIFY. 
2.  * 
3.  * This class was automatically generated by the 
4.  * aapt tool from the resource data it found.  It 
5.  * should not be modified by hand. 
6.  */  
7.   
8. package codesstore.calculator;  
9.   
10. public final class R {  
11.     public static final class attr {  
12.     }  
13.     public static final class drawable {  
14.         public static final int calculator_icon=0x7f020000;  
15.         public static final int ic_launcher=0x7f020001;  
16.     }  
17.     public static final class id {  
18.         public static final int answerbox=0x7f050004;  
19.         public static final int buttonDivide=0x7f050009;  
20.         public static final int buttonMinus=0x7f050008;  
21.         public static final int buttonMultiply=0x7f05000a;  
22.         public static final int buttonOk=0x7f05000b;  
23.         public static final int buttonPlus=0x7f050007;  
24.         public static final int buttons=0x7f050006;  
25.         public static final int inputs=0x7f050000;  
26.         public static final int num1=0x7f050001;  
27.         public static final int num2=0x7f050003;  
28.         public static final int textAnswer=0x7f050005;  
29.         public static final int textOperator=0x7f050002;  
30.     }  
31.     public static final class layout {  
32.         public static final int main=0x7f030000;  
33.     }  
34.     public static final class string {  
35.         public static final int app_name=0x7f040001;  
36.         public static final int title=0x7f040000;  
37.     }  
38. }  

/* AUTO-GENERATED FILE.  DO NOT MODIFY.
 *
 * This class was automatically generated by the
 * aapt tool from the resource data it found.  It
 * should not be modified by hand.
 */

package codesstore.calculator;

public final class R {
    public static final class attr {
    }
    public static final class drawable {
        public static final int calculator_icon=0x7f020000;
        public static final int ic_launcher=0x7f020001;
    }
    public static final class id {
        public static final int answerbox=0x7f050004;
        public static final int buttonDivide=0x7f050009;
        public static final int buttonMinus=0x7f050008;
        public static final int buttonMultiply=0x7f05000a;
        public static final int buttonOk=0x7f05000b;
        public static final int buttonPlus=0x7f050007;
        public static final int buttons=0x7f050006;
        public static final int inputs=0x7f050000;
        public static final int num1=0x7f050001;
        public static final int num2=0x7f050003;
        public static final int textAnswer=0x7f050005;
        public static final int textOperator=0x7f050002;
    }
    public static final class layout {
        public static final int main=0x7f030000;
    }
    public static final class string {
        public static final int app_name=0x7f040001;
        public static final int title=0x7f040000;
    }
}

Project structure in eclipse

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