Question

On Android Studio, create a 4 function calculator. The only buttons you need are 0-9, *, /, +, -, a clear, and enter button. Having this java code, I need the XML code that organizes the layout of the calculator.

JAVA CODE -

package com.example.10012698.calculatorproject;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.StringTokenizer;
public class MainActivity extends AppCompatActivity implements View.OnClickListener {

Button button0, button1, button2, button3, button4, button5, button6,
button7, button8, button9, buttonadd, buttonsubtract, buttonmultiply,
buttondivide, buttonequals, buttonclear;
TextView display;
String displaytext="";
double result;
double x, y;
ArrayList<String> list;

@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);
buttonadd = (Button) findViewById(R.id.buttonadd);
buttonsubtract = (Button) findViewById(R.id.buttonsubtract);
buttonmultiply = (Button) findViewById(R.id.buttonmultiply);
buttondivide = (Button) findViewById(R.id.buttondivide);
buttonclear = (Button) findViewById(R.id.buttonclear);
buttonequals = (Button) findViewById(R.id.buttonequals);
display = (TextView) findViewById(R.id.display);
display.setOnClickListener(this);
list = new ArrayList<>();
}

public void onClick(View view)
{
if(!(view.equals(buttonclear)&&!(view.equals(buttonequals))))
{
display.setText(display.getText()+""+((Button)view).getText());

if(displaytext.equals("0"))
{
display.setText(" ");
}

if(view.equals(buttonclear))
{
display.setText(" ");
}

if(view.equals(buttonequals))
{
displaytext= displaytext.substring(0,displaytext.length()-1);
StringTokenizer operators= new StringTokenizer(displaytext, "+-*/",true);

while(operators.hasMoreTokens())
{
list.add(operators.nextToken());
}

for(int j=0; j<list.size()-1; j++)
{
if (list.get(j).equals("*") || list.get(j).equals("/"))
{
x = Double.parseDouble(list.get(j - 1));
y = Double.parseDouble(list.get(j + 1));

if (list.get(j).equals("*"))
{
result+=(x*y);
}

if (list.get(j).equals("/"))
{
result+=(x/y);
}
}
}
for(int k=0;k<list.size()-1;k++)
{
if (list.get(k).equals("+") || list.get(k).equals("-"))
{
x = Double.parseDouble(list.get(k - 1));
y = Double.parseDouble(list.get(k + 1));

if (list.get(k).equals("+"))
{
result+=(x+y);
}

if (list.get(k).equals("-"))
{
result+=(x-y);
}
}
}
}
display.setText(""+result);

}
}

Answer 1

<?xml version="1.0" encoding="utf-8"?> <androidx.constraintlayout.widget.ConstraintLayout     xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:app="http://schemas.android.com/apk/res-auto"     xmlns:tools="http://schemas.android.com/tools"     android:layout_width="match_parent"     android:layout_height="match_parent"     android:background="#8BC34A"     android:backgroundTint="@android:color/darker_gray"     tools:context=".MainActivity">     <!-- Text View to display "gfg_myFirstApp "-->     <TextView         android:id="@+id/textView"         android:layout_width="133dp"         android:layout_height="28dp"         android:layout_marginStart="139dp"         android:layout_marginLeft="139dp"         android:layout_marginTop="16dp"         android:layout_marginEnd="139dp"         android:layout_marginRight="139dp"         android:layout_marginBottom="559dp"         <!-- providing the green colour to the background -->         android:background="#0F9D58"         android:text="gfg_myFirstApp"         android:textAppearance="@style/TextAppearance.AppCompat.Medium"         app:layout_constraintBottom_toBottomOf="parent"         app:layout_constraintEnd_toEndOf="parent"         app:layout_constraintStart_toStartOf="parent"         app:layout_constraintTop_toTopOf="parent" />     <!-- Text View to display our basic heading of "calculator"-->     <TextView         android:layout_width="194dp"         android:layout_height="43dp"         android:layout_marginStart="114dp"         android:layout_marginLeft="114dp"         android:layout_marginTop="58dp"         android:layout_marginEnd="103dp"         android:layout_marginRight="103dp"         android:layout_marginBottom="502dp"         android:scrollbarSize="30dp"         android:text="   Calculator"         android:textAppearance="@style/TextAppearance.AppCompat.Body1"         android:textSize="30dp"         app:layout_constraintBottom_toBottomOf="parent"         app:layout_constraintEnd_toEndOf="parent"         app:layout_constraintStart_toStartOf="parent"         app:layout_constraintTop_toTopOf="parent" />     <!-- Edit Text View to input the values -->     <EditText         android:id="@+id/num1"         android:layout_width="364dp"         android:layout_height="28dp"         android:layout_marginStart="72dp"         android:layout_marginTop="70dp"         android:layout_marginEnd="71dp"         android:layout_marginBottom="416dp"         android:background="@android:color/white"         android:ems="10"         android:hint="Number1(0)"         android:inputType="number"         app:layout_constraintBottom_toBottomOf="parent"         app:layout_constraintEnd_toEndOf="parent"         app:layout_constraintStart_toStartOf="parent"         app:layout_constraintTop_toTopOf="parent" />     <!-- Edit Text View to input 2nd value-->     <EditText         android:id="@+id/num2"         android:layout_width="363dp"         android:layout_height="30dp"         android:layout_marginStart="72dp"         android:layout_marginTop="112dp"         android:layout_marginEnd="71dp"         android:layout_marginBottom="374dp"         android:background="@android:color/white"         android:ems="10"         android:hint="number2(0)"         android:inputType="number"         app:layout_constraintBottom_toBottomOf="parent"         app:layout_constraintEnd_toEndOf="parent"         app:layout_constraintStart_toStartOf="parent"         app:layout_constraintTop_toTopOf="parent" />     <!-- Text View to display result -->     <TextView         android:id="@+id/result"         android:layout_width="356dp"         android:layout_height="71dp"         android:layout_marginStart="41dp"         android:layout_marginTop="151dp"         android:layout_marginEnd="48dp"         android:layout_marginBottom="287dp"         android:background="@android:color/white"         android:text="result"         android:textColorLink="#673AB7"         android:textSize="25sp"         app:layout_constraintBottom_toBottomOf="parent"         app:layout_constraintEnd_toEndOf="parent"         app:layout_constraintStart_toStartOf="parent"         app:layout_constraintTop_toTopOf="parent" />     <!-- A button to perform 'sum' operation -->     <Button         android:id="@+id/sum"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:layout_marginStart="16dp"         android:layout_marginTop="292dp"         android:layout_marginEnd="307dp"         android:layout_marginBottom="263dp"         android:backgroundTint="@android:color/holo_red_light"         android:onClick="doSum"         android:text="+"         app:layout_constraintBottom_toBottomOf="parent"         app:layout_constraintEnd_toEndOf="parent"         app:layout_constraintStart_toStartOf="parent"         app:layout_constraintTop_toTopOf="parent" />     <!-- A button to perform subtraction operation. -->     <Button         android:id="@+id/sub"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:layout_marginStart="210dp"         android:layout_marginTop="292dp"         android:layout_marginEnd="113dp"         android:layout_marginBottom="263dp"         android:backgroundTint="@android:color/holo_red_light"         android:onClick="doSub"         android:text="-"         app:layout_constraintBottom_toBottomOf="parent"         app:layout_constraintEnd_toEndOf="parent"         app:layout_constraintStart_toStartOf="parent"         app:layout_constraintTop_toTopOf="parent" />           <!-- A button to perform division. -->     <Button         android:id="@+id/div"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:layout_marginStart="307dp"         android:layout_marginTop="292dp"         android:layout_marginEnd="16dp"         android:layout_marginBottom="263dp"         android:backgroundTint="@android:color/holo_red_light"         android:onClick="doDiv"         android:text="/"         app:layout_constraintBottom_toBottomOf="parent"         app:layout_constraintEnd_toEndOf="parent"         app:layout_constraintHorizontal_bias="0.0"         app:layout_constraintStart_toStartOf="parent"         app:layout_constraintTop_toTopOf="parent" />           <!-- A button to perform multiplication. -->     <Button         android:id="@+id/mul"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:layout_marginStart="16dp"         android:layout_marginTop="356dp"         android:layout_marginEnd="307dp"         android:layout_marginBottom="199dp"         android:backgroundTint="@android:color/holo_red_light"         android:onClick="doMul"         android:text="x"         app:layout_constraintBottom_toBottomOf="parent"         app:layout_constraintEnd_toEndOf="parent"         app:layout_constraintStart_toStartOf="parent"         app:layout_constraintTop_toTopOf="parent" />          <!-- A button to perform a modulus function. -->     <Button         android:id="@+id/button"         android:layout_width="92dp"         android:layout_height="48dp"         android:layout_marginStart="113dp"         android:layout_marginTop="356dp"         android:layout_marginEnd="206dp"         android:layout_marginBottom="199dp"         android:backgroundTint="@android:color/holo_red_light"         android:onClick="doMod"         android:text="%(mod)"         app:layout_constraintBottom_toBottomOf="parent"         app:layout_constraintEnd_toEndOf="parent"         app:layout_constraintStart_toStartOf="parent"         app:layout_constraintTop_toTopOf="parent" />          <!-- A button to perform a power function. -->     <Button         android:id="@+id/pow"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:layout_marginStart="113dp"         android:layout_marginTop="292dp"         android:layout_marginEnd="210dp"         android:layout_marginBottom="263dp"         android:backgroundTint="@android:color/holo_red_light"         android:onClick="doPow"         android:text="n1^n2"         app:layout_constraintBottom_toBottomOf="parent"         app:layout_constraintEnd_toEndOf="parent"         app:layout_constraintStart_toStartOf="parent"         app:layout_constraintTop_toTopOf="parent" /> </androidx.constraintlayout.widget.ConstraintLayout>