Redirect Call in Android

In this tutorial, I will show you the code on how to redirect from your android apps to mobile call. Just see the code below.

String phoneCallUri = "tel:911";
Intent phoneCallIntent = new Intent(Intent.ACTION_DIAL);
phoneCallIntent.setData(Uri.parse(phoneCallUri));
 startActivity(phoneCallIntent);


That's it, Happy Coding.

Crop Image

In this tutorial i will show you how to crop an image in your android apps. I just refer this tutorial from this site. Just see the code below.


First thing you need to do is to create an Android Project. Second is create a two layouts named crop_selector.xml and main.xml.

crop_selector.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="10dp"
android:gravity="center_vertical">

<ImageView
android:id="@+id/iv_icon"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>

<TextView
android:id="@+id/tv_name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text=""/>

</LinearLayout>

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="fill_parent"
    android:layout_height="fill_parent">
    
<TextView  
   android:layout_width="fill_parent" 
   android:layout_height="wrap_content"
   android:layout_marginTop="10dp"
   android:layout_marginBottom="10dp"
   android:gravity="center"
   android:textStyle="bold"
   android:textSize="17sp"
   android:text="How to select and crop image"/>
   
<Button 
android:id="@+id/btn_crop"
android:layout_width="match_parent"  
android:layout_height="wrap_content"
android:text="Select image" />

<ImageView
android:id="@+id/iv_photo"
android:layout_marginTop="10dp"
android:layout_gravity="center_horizontal"
android:layout_width="fill_parent"  
android:layout_height="200dp"/>


</LinearLayout>

After you create the two layouts, you need to create 3 classes namely MainActivity.java, CropOption.java,  and CropOptionAdapter.

MainActivity.java

package net.londatiga.android;

import java.io.File;

import java.util.ArrayList;

import java.util.List;

import android.app.Activity;

import android.app.AlertDialog;

import android.content.ActivityNotFoundException;

import android.content.ComponentName;

import android.content.DialogInterface;

import android.content.Intent;

import android.content.pm.ResolveInfo;

import android.graphics.Bitmap;

import android.provider.MediaStore;

import android.view.View;

import android.net.Uri;

import android.os.Bundle;

import android.os.Environment;

import android.widget.Button;

import android.widget.ArrayAdapter;

import android.widget.Toast;

import android.widget.ImageView;

public class MainActivity extends Activity {

private Uri mImageCaptureUri;

private ImageView mImageView;

private static final int PICK_FROM_CAMERA = 1;

private static final int CROP_FROM_CAMERA = 2;

private static final int PICK_FROM_FILE = 3;

    @Override

    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        

        setContentView(R.layout.main);

        

        final String [] items = new String [] {"Take from camera", "Select from gallery"};

ArrayAdapter<String> adapter = new ArrayAdapter<String> (this, android.R.layout.select_dialog_item,items);

AlertDialog.Builder builder = new AlertDialog.Builder(this);

builder.setTitle("Select Image");

builder.setAdapter( adapter, new DialogInterface.OnClickListener() {

public void onClick( DialogInterface dialog, int item ) { //pick from camera

if (item == 0) {

Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);

mImageCaptureUri = Uri.fromFile(new File(Environment.getExternalStorageDirectory(),

  "tmp_avatar_" + String.valueOf(System.currentTimeMillis()) + ".jpg"));

intent.putExtra(android.provider.MediaStore.EXTRA_OUTPUT, mImageCaptureUri);

try {

intent.putExtra("return-data", true);

startActivityForResult(intent, PICK_FROM_CAMERA);

} catch (ActivityNotFoundException e) {

e.printStackTrace();

}

} else { //pick from file

Intent intent = new Intent();

               intent.setType("image/*");

               intent.setAction(Intent.ACTION_GET_CONTENT);

               

               startActivityForResult(Intent.createChooser(intent, "Complete action using"), PICK_FROM_FILE);

}

}

} );

final AlertDialog dialog = builder.create();

Button button = (Button) findViewById(R.id.btn_crop);

mImageView = (ImageView) findViewById(R.id.iv_photo);

button.setOnClickListener(new View.OnClickListener() {

@Override

public void onClick(View v) {

dialog.show();

}

});

    }

    

    @Override

protected void onActivityResult(int requestCode, int resultCode, Intent data) {

   if (resultCode != RESULT_OK) return;

  

   switch (requestCode) {

   case PICK_FROM_CAMERA:

    doCrop();

   

    break;

   

   case PICK_FROM_FILE: 

    mImageCaptureUri = data.getData();

   

    doCrop();

   

    break;    

   

   case CROP_FROM_CAMERA:    

       Bundle extras = data.getExtras();

       if (extras != null) {        

           Bitmap photo = extras.getParcelable("data");

           

           mImageView.setImageBitmap(photo);

       }

       File f = new File(mImageCaptureUri.getPath());            

       

       if (f.exists()) f.delete();

       break;

   }

}

    

    private void doCrop() {

final ArrayList<CropOption> cropOptions = new ArrayList<CropOption>();

   

    Intent intent = new Intent("com.android.camera.action.CROP");

        intent.setType("image/*");

        

        List<ResolveInfo> list = getPackageManager().queryIntentActivities( intent, 0 );

        

        int size = list.size();

        

        if (size == 0) {        

        Toast.makeText(this, "Can not find image crop app", Toast.LENGTH_SHORT).show();

       

            return;

        } else {

        intent.setData(mImageCaptureUri);

            

            intent.putExtra("outputX", 200);

            intent.putExtra("outputY", 200);

            intent.putExtra("aspectX", 1);

            intent.putExtra("aspectY", 1);

            intent.putExtra("scale", true);

            intent.putExtra("return-data", true);

            

        if (size == 1) {

        Intent i = new Intent(intent);

        ResolveInfo res = list.get(0);

       

        i.setComponent( new ComponentName(res.activityInfo.packageName, res.activityInfo.name));

       

        startActivityForResult(i, CROP_FROM_CAMERA);

        } else {

       for (ResolveInfo res : list) {

        final CropOption co = new CropOption();

       

        co.title = getPackageManager().getApplicationLabel(res.activityInfo.applicationInfo);

        co.icon = getPackageManager().getApplicationIcon(res.activityInfo.applicationInfo);

        co.appIntent= new Intent(intent);

       

        co.appIntent.setComponent( new ComponentName(res.activityInfo.packageName, res.activityInfo.name));

       

           cropOptions.add(co);

       }

       

       CropOptionAdapter adapter = new CropOptionAdapter(getApplicationContext(), cropOptions);

       

       AlertDialog.Builder builder = new AlertDialog.Builder(this);

       builder.setTitle("Choose Crop App");

       builder.setAdapter( adapter, new DialogInterface.OnClickListener() {

           public void onClick( DialogInterface dialog, int item ) {

               startActivityForResult( cropOptions.get(item).appIntent, CROP_FROM_CAMERA);

           }

       });

       

       builder.setOnCancelListener( new DialogInterface.OnCancelListener() {

           @Override

           public void onCancel( DialogInterface dialog ) {

              

               if (mImageCaptureUri != null ) {

                   getContentResolver().delete(mImageCaptureUri, null, null );

                   mImageCaptureUri = null;

               }

           }

       } );

       

       AlertDialog alert = builder.create();

       

       alert.show();

        }

        }

}

}

CropOption.java

package net.londatiga.android;

import android.content.Intent;

import android.graphics.drawable.Drawable;

public class CropOption {

public CharSequence title;

public Drawable icon;

public Intent appIntent;

}

CropOptionAdapter

package net.londatiga.android;

import android.view.LayoutInflater;

import android.view.View;

import android.view.ViewGroup;

import android.widget.ArrayAdapter;

import android.widget.ImageView;

import android.widget.TextView;

import android.content.Context;

import java.util.ArrayList;

/**

 * Adapter for crop option list.

 * 

 * @author Lorensius W. L. T <lorenz@londatiga.net>

 *

 */

public class CropOptionAdapter extends ArrayAdapter<CropOption> {

private ArrayList<CropOption> mOptions;

private LayoutInflater mInflater;

public CropOptionAdapter(Context context, ArrayList<CropOption> options) {

super(context, R.layout.crop_selector, options);

mOptions = options;

mInflater = LayoutInflater.from(context);

}

@Override

public View getView(int position, View convertView, ViewGroup group) {

if (convertView == null)

convertView = mInflater.inflate(R.layout.crop_selector, null);

CropOption item = mOptions.get(position);

if (item != null) {

((ImageView) convertView.findViewById(R.id.iv_icon)).setImageDrawable(item.icon);

((TextView) convertView.findViewById(R.id.tv_name)).setText(item.title);

return convertView;

}

return null;

}

}

That's it. Anyway there's a lot of tutorial around like this crop image and croping. Sorry if I didn't show the output because I can't upload the output image... Hope this simple tutorial may help you...

Change dot to Asterisk in Password

In this tutorial, I will show you how to change the default value for password which is dot(.) to asterisk(*). See the code below.

//create a child class of your main class
class AsteriskPasswordTransformationMethod extends PasswordTransformationMethod {
    @Override
    public CharSequence getTransformation(CharSequence source, View view) {
        return new PasswordCharSequence(source);
    }

    private class PasswordCharSequence implements CharSequence {
        private CharSequence mSource;
        public PasswordCharSequence(CharSequence source) {
            mSource = source; // Store char sequence
        }
        public char charAt(int index) {
            return '*'; // This is the important part
        }
        public int length() {
            return mSource.length(); // Return default
        }
        public CharSequence subSequence(int start, int end) {
            return mSource.subSequence(start, end); // Return default
        }
    }
};


//then call this class wherever you need to change the dot to asterisk.
final EditText et_pin1 = (EditText)dl.findViewById(R.id.et_verify1);et_pin1.setTransformationMethod(new AsteriskPasswordTransformationMethod());


That's it, hope this simple tutorial will help you something. Happy Coding

Customized dialog within the Activity

In this post, I will show you how to create a customized dialog in Android. I can't show you the output because I can't upload image at this time. I will just show you some codes.

//declare a dl variable for dialog at the top
private Dialog dl;


//user this code whereever you need it.
dl = new Dialog(Send_Money.this);
dl.getWindow().requestFeature(Window.FEATURE_NO_TITLE);
dl.getWindow().setBackgroundDrawable(new ColorDrawable(android.graphics.Color.TRANSPARENT));
dl.setContentView(getLayoutInflater().inflate(R.layout.send_money_option_dialog, null));
dl.getWindow().getAttributes().windowAnimations = R.style.dialog_animation;

TextView tv_msg = (TextView)dl.findViewById(R.id.tv_message);
TextView tv_title = (TextView)dl.findViewById(R.id.tv_dialog_title);


tv_title.setText("TITLE");
tv_msg.setText("Message");

Button btn_one = (Button) dl.findViewById(R.id.btn_dialog_btn_one);
Button btn_two = (Button) dl.findViewById(R.id.btn_dialog_btn_two );
Button btn_three = (Button) dl.findViewById(R.id.btn_dialog_btn_three);

btn_one .setOnClickListener(new View.OnClickListener() {

@Override
public void onClick(View v) {

//do some code for button one

}
});


btn_two .setOnClickListener(new View.OnClickListener() {

@Override
public void onClick(View v) {

//do some code for button two

}
});

btn_three .setOnClickListener(new View.OnClickListener() {

@Override
public void onClick(View v) {

//do some code for button three

}
});

dl.show();
}



That's it, hope this simple tutorial will help youo. Happy Coding.    

Redirect to SMS

In this tutorial, I will show you some tutorial that redirecting or passing message to built in Messages Apps in your Android phone. From your Android Apps, you pass a message to it messages field. See the code below.

Intent smsIntent = new Intent(Intent.ACTION_VIEW);
smsIntent.setData(Uri.parse("sms:"));
smsIntent.putExtra("sms_body", "Your message"));
startActivity(smsIntent);


To only send a number, use this code.

startActivity(new Intent(Intent.ACTION_VIEW, Uri.fromParts("sms", "number", null)));


That's it, hope this simple tutorial will help you. Happy Coding...

Login Validation

In this tutorial, I will show you how to validate login using static input. See output below.

Here's the view of my project.

Here's the code of LoginModel.java

package com.example.model;

public class LoginModel {

public String m_email, m_password;

//constructor
public LoginModel(String email, String password){
this.m_email = email;
this.m_password = password;
}

}

Here's the code of Controller.java

package com.example.controller;

import java.util.regex.Pattern;

import android.util.Patterns;

import com.example.model.LoginModel;

public class Controller{

//static variables
private static final String EMAIL = "gaudicos61@gmail.com";
private static final String PASSWORD = "gaudicos";

@SuppressWarnings("unused")
public boolean isCheckEmail(LoginModel model) {
Pattern pattern = Patterns.EMAIL_ADDRESS;
if(pattern.matcher(model.m_email).matches() == true && model.m_email.equals(EMAIL)){
return true;
}else{
return false;
}
}



public boolean isCheckPassword(LoginModel model){
if(PASSWORD.equals(model.m_password)){
return true;
}else{
return false;
}
}

}

Here's the code of MainActivity.java

package com.example.menudesign;

import android.app.Activity;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import com.example.controller.Controller;
import com.example.model.LoginModel;

public class MainActivity extends Activity implements OnClickListener{

private EditText et_email,et_password;
private TextView tv_error_email, tv_error_pass;
private Button btn_login;

LoginModel model;
Controller c_controller;

private int email_indicator = 0, password_indicator = 0;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

initializeVars();


}

public void initializeVars(){
et_email = (EditText)findViewById(R.id.et_sample1);
et_password = (EditText)findViewById(R.id.et_sample2);
tv_error_email = (TextView)findViewById(R.id.tv_validate_email);
tv_error_pass = (TextView)findViewById(R.id.tv_validate_password);
btn_login = (Button)findViewById(R.id.btn_login);
tv_error_email.setVisibility(View.INVISIBLE);
tv_error_pass.setVisibility(View.INVISIBLE);
btn_login.setEnabled(false);

btn_login.setOnClickListener(this);

//listen the the editText when it's value changed
TextWatcher watcher = new TextWatcher() {

public void afterTextChanged(Editable s) {

model = new LoginModel(et_email.getText().toString(), et_password.getText().toString());
c_controller = new Controller();
   
try{ 
if(c_controller.isCheckEmail(model) == false && c_controller.isCheckPassword(model) == false){
     
tv_error_email.setVisibility(View.VISIBLE);
tv_error_email.setText("Invalid email address or doesnt match.");
tv_error_pass.setVisibility(View.VISIBLE);
tv_error_pass.setText("Invalid password or doesnt match.");
btn_login.setEnabled(false);
email_indicator = 0;
    password_indicator = 0;    
     
}else if(c_controller.isCheckEmail(model) == true && c_controller.isCheckPassword(model) == false){
     
   tv_error_pass.setVisibility(View.VISIBLE);
   tv_error_pass.setText("Invalid password or doesnt match.");
   btn_login.setEnabled(false);
   email_indicator = 1;
    password_indicator = 0;
   
    }else if(c_controller.isCheckEmail(model) == false && c_controller.isCheckPassword(model) == true){
     
    tv_error_email.setVisibility(View.VISIBLE);
    tv_error_email.setText("Invalid email address or doesnt match.");
    btn_login.setEnabled(false);
    email_indicator = 0;
    password_indicator = 1;
   
    }else{
   //means all input are valid, code here to login...
    email_indicator = 1;
    password_indicator = 1;
    btn_login.setEnabled(true);
    }
   

}catch(StringIndexOutOfBoundsException e){
     e.printStackTrace();
}
}

@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
// TODO Auto-generated method stub
}

@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
// TODO Auto-generated method stub
tv_error_email.setVisibility(View.INVISIBLE);
tv_error_pass.setVisibility(View.INVISIBLE);
};
};


et_email.addTextChangedListener(watcher);
et_password.addTextChangedListener(watcher);
}

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
switch(v.getId()){
case R.id.btn_login:
if(email_indicator == 1 && password_indicator == 1){
Toast.makeText(getApplicationContext(), "You can now log in here!", Toast.LENGTH_SHORT).show();
}
}
}



}

Here's the code of activity_main.xml

<RelativeLayout 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: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/et_sample1"
        android:layout_width="500dp"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="46dp" >

        <requestFocus />
    </EditText>

    <EditText
        android:id="@+id/et_sample2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/et_sample1"
        android:layout_alignRight="@+id/et_sample1"
        android:layout_below="@+id/et_sample1"
        android:layout_marginTop="10dp" />

    <TextView
        android:id="@+id/tv_validate_email"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignRight="@+id/et_sample2"
        android:layout_below="@+id/et_sample1"
        android:textSize="12sp"
        android:visibility="gone"
        android:textColor="#FFFFFF"
        android:background="@drawable/ic_error_bg" />
    
    
    <TextView
        android:id="@+id/tv_validate_password"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignRight="@+id/et_sample2"
        android:layout_below="@+id/et_sample2"
        android:textSize="12sp"
        android:visibility="gone"
        android:textColor="#FFFFFF"
        android:background="@drawable/ic_error_bg" />

    <Button
        android:id="@+id/btn_login"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/tv_validate_password"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="31dp"
        android:text="Login" />


</RelativeLayout>

That's it, hope this simple tutorial may help you. Happy Coding.

Basic Calculator

In this tutorial, I will show you how to create simple calculator in Android. See output below!

Here's the CalculatorModel.java

package com.example.calculator;

public class CalculatorModel {

double m_num1, m_num2;

//constructor

public CalculatorModel(double num1, double num2){
this.m_num1 = num1;
this.m_num2 = num2;
}

//setters

public void setNum1(double num1){
this.m_num1 = num1;
}

public void setNum2(double num2){
this.m_num2 = num2;
}

//getters

public double getNum1(){
return this.m_num1;
}

public double getNum2(){
return this.m_num2;
}

}

Here's the CalculatorController.java

package com.example.calculator;

public class CalculatorController {

public double addition(CalculatorModel cmodel){

return cmodel.m_num1 + cmodel.m_num2;

}

public double subtraction(CalculatorModel cmodel){

return cmodel.m_num1 - cmodel.m_num2;

}

public double multiplication(CalculatorModel cmodel){

return cmodel.m_num1 * cmodel.m_num2;

}

public double divistion(CalculatorModel cmodel){

return cmodel.m_num1 / cmodel.m_num2;

}

}

Here's the CalculatorActivity.java

package com.example.calculator;

import android.app.Activity;

import android.os.Bundle;

import android.view.Menu;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

import android.widget.EditText;

public class CalculatorActivity extends Activity implements OnClickListener{

EditText et_result;

Button btn_one, btn_two, btn_three, btn_four, btn_five, btn_six, btn_seven, 

btn_eight, btn_nine, btn_zero, btn_point, btn_add, btn_minus, btn_times, 

btn_divide, btn_equal, btn_clear;

double num1 = 0;

int indicator = 0;

CalculatorModel c_model;

CalculatorController c_controller;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_calculator);

initializeVars();

}

@Override

public boolean onCreateOptionsMenu(Menu menu) {

// Inflate the menu; this adds items to the action bar if it is present.

getMenuInflater().inflate(R.menu.calculator, menu);

return true;

}

public void initializeVars(){

et_result = (EditText)findViewById(R.id.et_result);

btn_one = (Button)findViewById(R.id.btn_one);

btn_two = (Button)findViewById(R.id.btn_two);

btn_three = (Button)findViewById(R.id.btn_three);

btn_four = (Button)findViewById(R.id.btn_four);

btn_five = (Button)findViewById(R.id.btn_five);

btn_six = (Button)findViewById(R.id.btn_six);

btn_seven = (Button)findViewById(R.id.btn_seven);

btn_eight = (Button)findViewById(R.id.btn_eight);

btn_nine = (Button)findViewById(R.id.btn_nine);

btn_zero = (Button)findViewById(R.id.btn_zero);

btn_point = (Button)findViewById(R.id.btn_point);

btn_add = (Button)findViewById(R.id.btn_add);

btn_minus = (Button)findViewById(R.id.btn_minus);

btn_times = (Button)findViewById(R.id.btn_times);

btn_divide = (Button)findViewById(R.id.btn_divide);

btn_equal = (Button)findViewById(R.id.btn_equal);

btn_clear = (Button)findViewById(R.id.btn_clear);

btn_one.setOnClickListener(this);

btn_two.setOnClickListener(this);

btn_three.setOnClickListener(this);

btn_four.setOnClickListener(this);

btn_five.setOnClickListener(this);

btn_six.setOnClickListener(this);

btn_seven.setOnClickListener(this);

btn_eight.setOnClickListener(this);

btn_nine.setOnClickListener(this);

btn_zero.setOnClickListener(this);

btn_point.setOnClickListener(this);

btn_add.setOnClickListener(this);

btn_minus.setOnClickListener(this);

btn_times.setOnClickListener(this);

btn_divide.setOnClickListener(this);

btn_equal.setOnClickListener(this);

btn_clear.setOnClickListener(this);

}

@Override

public void onClick(View v) {

// TODO Auto-generated method stub

try{

switch(v.getId()){

case R.id.btn_one:

et_result.setText(et_result.getText().toString()+btn_one.getText().toString());

break;

case R.id.btn_two:

et_result.setText(et_result.getText().toString()+btn_two.getText().toString());

break;

case R.id.btn_three:

et_result.setText(et_result.getText().toString()+btn_three.getText().toString());

break;

case R.id.btn_four:

et_result.setText(et_result.getText().toString()+btn_four.getText().toString());

break;

case R.id.btn_five:

et_result.setText(et_result.getText().toString()+btn_five.getText().toString());

break;

case R.id.btn_six:

et_result.setText(et_result.getText().toString()+btn_six.getText().toString());

break;

case R.id.btn_seven:

et_result.setText(et_result.getText().toString()+btn_seven.getText().toString());

break;

case R.id.btn_eight:

et_result.setText(et_result.getText().toString()+btn_eight.getText().toString());

break;

case R.id.btn_nine:

et_result.setText(et_result.getText().toString()+btn_nine.getText().toString());

break;

case R.id.btn_zero:

et_result.setText(et_result.getText().toString()+btn_zero.getText().toString());

break;

case R.id.btn_point:

et_result.setText(et_result.getText().toString()+btn_point.getText().toString());

break;

case R.id.btn_add:

num1 = Double.parseDouble(et_result.getText().toString());

et_result.setText("");

indicator = 1;

break;

case R.id.btn_minus:

num1 = Double.parseDouble(et_result.getText().toString());

et_result.setText("");

indicator = 2;

break;

case R.id.btn_times:

num1 = Double.parseDouble(et_result.getText().toString());

et_result.setText("");

indicator = 3;

break;

case R.id.btn_divide:

num1 = Double.parseDouble(et_result.getText().toString());

et_result.setText("");

indicator = 4;

break;

case R.id.btn_clear:

et_result.setText("");

break;

case R.id.btn_equal:

c_model = new CalculatorModel(num1, Double.parseDouble(et_result.getText().toString()));

c_controller = new CalculatorController();

switch(indicator){

case 1:

et_result.setText(Double.toString(c_controller.addition(c_model)));

break;

case 2:

et_result.setText(Double.toString(c_controller.subtraction(c_model)));

break;

case 3:

et_result.setText(Double.toString(c_controller.multiplication(c_model)));

break;

case 4:

et_result.setText(Double.toString(c_controller.divistion(c_model)));

break;

}

break;

}

}catch(Exception e){

e.printStackTrace();

}

}

}

And lastly, the activity_calculator.xml

<RelativeLayout 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: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=".CalculatorActivity" >

    <RelativeLayout 

        android:id="@+id/rl_hold_calculator"

        android:layout_width="250dp"

        android:layout_height="wrap_content"

        android:layout_centerHorizontal="true"

        android:layout_centerVertical="true">

        "

   <EditText

       android:id="@+id/et_result"

       android:layout_width="fill_parent"

       android:layout_height="wrap_content"

       android:layout_marginTop="20dp"

       android:ems="10"

       android:inputType="numberDecimal" >

       <requestFocus />

   </EditText>

   <Button

       android:id="@+id/btn_one"

       android:layout_width="wrap_content"

       android:layout_height="wrap_content"

       android:layout_alignLeft="@+id/et_result"

       android:layout_below="@+id/et_result"

       android:layout_marginTop="10dp"

       android:text="1" />

   <Button

       android:id="@+id/btn_two"

       android:layout_width="wrap_content"

       android:layout_height="wrap_content"

       android:layout_alignBaseline="@+id/btn_one"

       android:layout_alignBottom="@+id/btn_one"

       android:layout_toRightOf="@+id/btn_one"

       android:text="2" />

   <Button

       android:id="@+id/btn_three"

       android:layout_width="wrap_content"

       android:layout_height="wrap_content"

       android:layout_alignBaseline="@+id/btn_two"

       android:layout_alignBottom="@+id/btn_two"

       android:layout_toRightOf="@+id/btn_two"

       android:text="3" />

   <Button

       android:id="@+id/btn_four"

       android:layout_width="wrap_content"

       android:layout_height="wrap_content"

       android:layout_alignBaseline="@+id/btn_three"

       android:layout_alignBottom="@+id/btn_three"

       android:layout_toRightOf="@+id/btn_three"

       android:text="4" />

   <Button

       android:id="@+id/btn_five"

       android:layout_width="wrap_content"

       android:layout_height="wrap_content"

       android:layout_alignLeft="@+id/btn_one"

       android:layout_below="@+id/btn_one"

       android:layout_marginTop="10dp"

       android:text="5" />

   <Button

       android:id="@+id/btn_six"

       android:layout_width="wrap_content"

       android:layout_height="wrap_content"

       android:layout_alignBaseline="@+id/btn_five"

       android:layout_alignBottom="@+id/btn_five"

       android:layout_alignLeft="@+id/btn_two"

       android:text="6" />

   <Button

       android:id="@+id/btn_seven"

       android:layout_width="wrap_content"

       android:layout_height="wrap_content"

       android:layout_alignBaseline="@+id/btn_six"

       android:layout_alignBottom="@+id/btn_six"

       android:layout_alignLeft="@+id/btn_three"

       android:text="7" />

   <Button

       android:id="@+id/btn_eight"

       android:layout_width="wrap_content"

       android:layout_height="wrap_content"

       android:layout_alignBaseline="@+id/btn_seven"

       android:layout_alignBottom="@+id/btn_seven"

       android:layout_toRightOf="@+id/btn_seven"

       android:text="8" />

    

    

   <Button

       android:id="@+id/btn_nine"

       android:layout_width="wrap_content"

       android:layout_height="wrap_content"

       android:layout_alignLeft="@+id/btn_five"

       android:layout_below="@+id/btn_five"

       android:layout_marginTop="10dp"

       android:text="9" />

   <Button

       android:id="@+id/btn_zero"

       android:layout_width="wrap_content"

       android:layout_height="wrap_content"

       android:layout_alignBaseline="@+id/btn_nine"

       android:layout_alignBottom="@+id/btn_nine"

       android:layout_toRightOf="@+id/btn_nine"

       android:text="0" />

   <Button

       android:id="@+id/btn_point"

       android:layout_width="wrap_content"

       android:layout_height="wrap_content"

       android:layout_alignBaseline="@+id/btn_zero"

       android:layout_alignBottom="@+id/btn_zero"

       android:layout_toRightOf="@+id/btn_zero"

       android:text="." />

   <Button

       android:id="@+id/btn_clear"

       android:layout_width="wrap_content"

       android:layout_height="wrap_content"

       android:layout_alignBaseline="@+id/btn_point"

       android:layout_alignBottom="@+id/btn_point"

       android:layout_toRightOf="@+id/btn_point"

       android:text="C" />

   <Button

       android:id="@+id/btn_add"

       android:layout_width="wrap_content"

       android:layout_height="wrap_content"

       android:layout_alignLeft="@+id/btn_nine"

       android:layout_below="@+id/btn_nine"

       android:layout_marginTop="10dp"

       android:text="+" />

   <Button

       android:id="@+id/btn_minus"

       android:layout_width="wrap_content"

       android:layout_height="wrap_content"

       android:layout_alignBaseline="@+id/btn_add"

       android:layout_alignBottom="@+id/btn_add"

       android:layout_toRightOf="@+id/btn_add"

       android:text="-" />

   <Button

       android:id="@+id/btn_times"

       android:layout_width="wrap_content"

       android:layout_height="wrap_content"

       android:layout_alignBaseline="@+id/btn_minus"

       android:layout_alignBottom="@+id/btn_minus"

       android:layout_alignLeft="@+id/btn_point"

       android:text="*" />

   <Button

       android:id="@+id/btn_divide"

       android:layout_width="wrap_content"

       android:layout_height="wrap_content"

       android:layout_alignBaseline="@+id/btn_times"

       android:layout_alignBottom="@+id/btn_times"

       android:layout_alignLeft="@+id/btn_clear"

       android:text="/" />

   <Button

       android:id="@+id/btn_equal"

       android:layout_width="wrap_content"

       android:layout_height="wrap_content"

       android:layout_alignLeft="@+id/btn_add"

       android:layout_alignParentRight="true"

       android:layout_below="@+id/btn_add"

       android:layout_marginTop="10dp"

       android:text="=" />

    

    </RelativeLayout>

</RelativeLayout>

That's it, hope this simple tutorial may help you. Happy Coding!