how to create Calculator in android studio

Let's started with our calculator android App

Hello, friends and this is my first video and I am trying my best in this video. I have to make a CALCULATOR APP in the android studio. you can learn coding in an easy way and you can make your own application through the android studio.

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Step-1

• Open your Android Studio
• Click on Start a New Android Studio Project.
• Give your Application Name wctutorialcalculator  and leave other fields blank as it is, then clicks NEXT.

Step-2

• Select the Minimum SDK API 15: Android 4.0.3(IceCreamSandwich). I selected because it covers almost 94% device and it has almost all the features. If you want to cover 100% device then you can select API 8: Android 2.2(Froyo).

Step-3

• Select the Empty Activity and click NEXT.
• Leave the activity name MainActivity as it is and leave everything as it is. Click Finish.

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Step-4

• After clicking Finish, it takes around ~2-3 minutes to build Activity and files.
• Here is a final project structure for your application.

Step-5

• Now we have to add our Java code in our MainActivity.java file.
• So open you MainActivity.java file from left side of IDE (app  -> java -> com.wctutorial.wctutorialcalculator -> MainActivity.java)

package com.wctutorial.tutorials.wctutorialcalculator; import android.os.Bundle; import android.support.v7.app.AppCompatActivity; import android.view.View; import android.widget.Button; import android.widget.EditText; public class MainActivity extends AppCompatActivity { Button button0, button1, button2, button3, button4, button5, button6, button7, button8, button9, buttonAdd, buttonSub, buttonDivision, buttonMul, button10, buttonC, buttonEqual; EditText wctutorialEditText; float mValueOne, mValueTwo; boolean wctutorialAddition, mSubtract, wctutorialMultiplication, wctutorialDivision; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); button0 = (Button) findViewById(R.id.button0); button1 = (Button) findViewById(R.id.button1); button2 = (Button) findViewById(R.id.button2); button3 = (Button) findViewById(R.id.button3); button4 = (Button) findViewById(R.id.button4); button5 = (Button) findViewById(R.id.button5); button6 = (Button) findViewById(R.id.button6); button7 = (Button) findViewById(R.id.button7); button8 = (Button) findViewById(R.id.button8); button9 = (Button) findViewById(R.id.button9); button10 = (Button) findViewById(R.id.button10); buttonAdd = (Button) findViewById(R.id.buttonadd); buttonSub = (Button) findViewById(R.id.buttonsub); buttonMul = (Button) findViewById(R.id.buttonmul); buttonDivision = (Button) findViewById(R.id.buttondiv); buttonC = (Button) findViewById(R.id.buttonC); buttonEqual = (Button) findViewById(R.id.buttoneql); wctutorialEditText = (EditText) findViewById(R.id.edt1); button1.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { wctutorialEditText.setText(wctutorialEditText.getText() + "1"); } }); button2.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { wctutorialEditText.setText(wctutorialEditText.getText() + "2"); } }); button3.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { wctutorialEditText.setText(wctutorialEditText.getText() + "3"); } }); button4.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { wctutorialEditText.setText(wctutorialEditText.getText() + "4"); } }); button5.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { wctutorialEditText.setText(wctutorialEditText.getText() + "5"); } }); button6.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { wctutorialEditText.setText(wctutorialEditText.getText() + "6"); } }); button7.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { wctutorialEditText.setText(wctutorialEditText.getText() + "7"); } }); button8.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { wctutorialEditText.setText(wctutorialEditText.getText() + "8"); } }); button9.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { wctutorialEditText.setText(wctutorialEditText.getText() + "9"); } }); button0.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { wctutorialEditText.setText(wctutorialEditText.getText() + "0"); } }); buttonAdd.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { if (wctutorialEditText == null) { wctutorialEditText.setText(""); } else { mValueOne = Float.parseFloat(wctutorialEditText.getText() + ""); wctutorialAddition = true; wctutorialEditText.setText(null); } } }); buttonSub.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { mValueOne = Float.parseFloat(wctutorialEditText.getText() + ""); mSubtract = true; wctutorialEditText.setText(null); } }); buttonMul.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { mValueOne = Float.parseFloat(wctutorialEditText.getText() + ""); wctutorialMultiplication = true; wctutorialEditText.setText(null); } }); buttonDivision.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { mValueOne = Float.parseFloat(wctutorialEditText.getText() + ""); wctutorialDivision = true; wctutorialEditText.setText(null); } }); buttonEqual.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { mValueTwo = Float.parseFloat(wctutorialEditText.getText() + ""); if (wctutorialAddition == true) { wctutorialEditText.setText(mValueOne + mValueTwo + ""); wctutorialAddition = false; } if (mSubtract == true) { wctutorialEditText.setText(mValueOne - mValueTwo + ""); mSubtract = false; } if (wctutorialMultiplication == true) { wctutorialEditText.setText(mValueOne * mValueTwo + ""); wctutorialMultiplication = false; } if (wctutorialDivision == true) { wctutorialEditText.setText(mValueOne / mValueTwo + ""); wctutorialDivision = false; } } }); buttonC.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { wctutorialEditText.setText(""); } }); button10.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { wctutorialEditText.setText(wctutorialEditText.getText() + "."); } }); } }

• In-Line 156 – 183: Here we set click listener on “=” button. We put condition like if the user click the Add button the wctutorialAddition value is set True on the click listener of the Add button.

if (wctutorialAddition == true) { wctutorialEditText.setText(mValueOne + mValueTwo + ""); wctutorialAddition = false; }

• After we set the crunchifyAddition value to false, so that we can perform Add an action again.

<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/relative1" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity"> <EditText android:id="@+id/edt1" android:layout_width="match_parent" android:layout_height="wrap_content" /> <Button android:id="@+id/button1" style="?android:attr/buttonStyleSmall" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignEnd="@+id/button4" android:layout_alignRight="@+id/button4" android:layout_below="@+id/edt1" android:layout_marginTop="94dp" android:text="1" /> <Button android:id="@+id/button2" style="?android:attr/buttonStyleSmall" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignTop="@+id/button1" android:layout_toLeftOf="@+id/button3" android:layout_toStartOf="@+id/button3" android:text="2" /> <Button android:id="@+id/button3" style="?android:attr/buttonStyleSmall" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignTop="@+id/button2" android:layout_centerHorizontal="true" android:text="3" /> <Button android:id="@+id/button4" style="?android:attr/buttonStyleSmall" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_below="@+id/button1" android:layout_toLeftOf="@+id/button2" android:text="4" /> <Button android:id="@+id/button5" style="?android:attr/buttonStyleSmall" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignBottom="@+id/button4" android:layout_alignLeft="@+id/button2" android:layout_alignStart="@+id/button2" android:text="5" /> <Button android:id="@+id/button6" style="?android:attr/buttonStyleSmall" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignLeft="@+id/button3" android:layout_alignStart="@+id/button3" android:layout_below="@+id/button3" android:text="6" /> <Button android:id="@+id/button7" style="?android:attr/buttonStyleSmall" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_below="@+id/button4" android:layout_toLeftOf="@+id/button2" android:text="7" /> <Button android:id="@+id/button8" style="?android:attr/buttonStyleSmall" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignLeft="@+id/button5" android:layout_alignStart="@+id/button5" android:layout_below="@+id/button5" android:text="8" /> <Button android:id="@+id/button9" style="?android:attr/buttonStyleSmall" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignLeft="@+id/button6" android:layout_alignStart="@+id/button6" android:layout_below="@+id/button6" android:text="9" /> <Button android:id="@+id/buttonadd" style="?android:attr/buttonStyleSmall" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignEnd="@+id/edt1" android:layout_alignRight="@+id/edt1" android:layout_alignTop="@+id/button3" android:layout_marginLeft="46dp" android:layout_marginStart="46dp" android:layout_toRightOf="@+id/button3" android:text="+" /> <Button android:id="@+id/buttonsub" style="?android:attr/buttonStyleSmall" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignEnd="@+id/buttonadd" android:layout_alignLeft="@+id/buttonadd" android:layout_alignRight="@+id/buttonadd" android:layout_alignStart="@+id/buttonadd" android:layout_below="@+id/buttonadd" android:text="-" /> <Button android:id="@+id/buttonmul" style="?android:attr/buttonStyleSmall" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignLeft="@+id/buttonsub" android:layout_alignParentEnd="true" android:layout_alignParentRight="true" android:layout_alignStart="@+id/buttonsub" android:layout_below="@+id/buttonsub" android:text="*" /> <Button android:id="@+id/button10" style="?android:attr/buttonStyleSmall" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_below="@+id/button7" android:layout_toLeftOf="@+id/button2" android:text="." /> <Button android:id="@+id/button0" style="?android:attr/buttonStyleSmall" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignLeft="@+id/button8" android:layout_alignStart="@+id/button8" android:layout_below="@+id/button8" android:text="0" /> <Button android:id="@+id/buttonC" style="?android:attr/buttonStyleSmall" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignLeft="@+id/button9" android:layout_alignStart="@+id/button9" android:layout_below="@+id/button9" android:text="C" /> <Button android:id="@+id/buttondiv" style="?android:attr/buttonStyleSmall" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignEnd="@+id/buttonmul" android:layout_alignLeft="@+id/buttonmul" android:layout_alignRight="@+id/buttonmul" android:layout_alignStart="@+id/buttonmul" android:layout_below="@+id/buttonmul" android:text="/" /> <Button android:id="@+id/buttoneql" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignEnd="@+id/buttondiv" android:layout_alignLeft="@+id/button10" android:layout_alignRight="@+id/buttondiv" android:layout_alignStart="@+id/button10" android:layout_below="@+id/button0" android:layout_marginTop="37dp" android:text="=" /> </RelativeLayout>

Now Ready to run the calculator app.