calculator program in java

1import java.util.Scanner;
2public class Calculator {
3   public static void main(String[] args) {
4      double num1;
5      double num2;
6      double ans;
7      char op;
8      Scanner reader = new Scanner(System.in);
9      System.out.print("Enter two numbers: ");
10      num1 = reader.nextDouble();
11      num2 = reader.nextDouble();
12      System.out.print("\nEnter an operator (+, -, *, /): ");
13      op = reader.next().charAt(0);
14      switch(op) {
15         case '+': ans = num1 + num2;
16            break;
17         case '-': ans = num1 - num2;
18            break;
19         case '*': ans = num1 * num2;
20            break;
21         case '/': ans = num1 / num2;
22            break;
23      default: System.out.printf("Error! Enter correct operator");
24         return;
25      }
26      System.out.print("\nThe result is given as follows:\n");
27      System.out.printf(num1 + " " + op + " " + num2 + " = " + ans);
28   }
29}

1// this was all coded by me, to use it get Eclipse, or IntelliJ and make a new
2// Java Project
3
4package javaCode;
5
6import java.util.Scanner;
7
8public class testCode {
9
10	public static void main(String[] args) {
11		
12		Scanner scan = new Scanner(System.in);
13		
14		System.out.println("Would you like to Add, Subtract, Divide, or Multiply?");
15		
16		String mathType = scan.next();
17		
18		if (mathType.equalsIgnoreCase("add")) {
19			System.out.println("Whats the first number you want to add?");
20			
21			int firstNumber = scan.nextInt();
22			
23			System.out.println(firstNumber + " + ");
24			System.out.println("Enter your second number");
25			
26			int secondNumber = scan.nextInt();
27			
28			System.out.println(firstNumber + " + " + secondNumber + " =");
29			System.out.println(firstNumber + secondNumber);
30			
31		} else if (mathType.equalsIgnoreCase("subtract")) {
32			System.out.println("Whats the first number you want to subtract?");
33			
34			int firstNumber = scan.nextInt();
35			
36			System.out.println(firstNumber + " - ");
37			System.out.println("Enter your second number");
38			
39			int secondNumber = scan.nextInt();
40			
41			System.out.println(firstNumber + " - " + secondNumber + " =");
42			System.out.println(firstNumber - secondNumber);
43		} else if (mathType.equalsIgnoreCase("divide")) {
44			System.out.println("Whats the first number you want to divide?");
45			
46			int firstNumber = scan.nextInt();
47			
48			System.out.println(firstNumber + " % ");
49			System.out.println("Enter your second number");
50			
51			int secondNumber = scan.nextInt();
52			
53			System.out.println(firstNumber + " % " + secondNumber + " =");
54			System.out.println(firstNumber / secondNumber);
55		} else if (mathType.equalsIgnoreCase("multiply")){
56			System.out.println("Whats the first number you want to multiply?");
57			
58			int firstNumber = scan.nextInt();
59			
60			System.out.println(firstNumber + " x ");
61			System.out.println("Enter your second number");
62			
63			int secondNumber = scan.nextInt();
64			
65			System.out.println(firstNumber + " x " + secondNumber + " =");
66			System.out.println(firstNumber * secondNumber);
67		}
68		
69	}
70
71}

1Save this file as MyCalculator.java 
2to compile it use 
3    javac MyCalculator.java 
4to use the calcuator do this 
5    java MyCalculator 
6 
7**********************************************/  
8import java.awt.*;  
9import java.awt.event.*;  
10/*********************************************/  
11  
12public class MyCalculator extends Frame  
13{  
14  
15public boolean setClear=true;  
16double number, memValue;  
17char op;  
18  
19String digitButtonText[] = {"7", "8", "9", "4", "5", "6", "1", "2", "3", "0", "+/-", "." };  
20String operatorButtonText[] = {"/", "sqrt", "*", "%", "-", "1/X", "+", "=" };  
21String memoryButtonText[] = {"MC", "MR", "MS", "M+" };  
22String specialButtonText[] = {"Backspc", "C", "CE" };  
23  
24MyDigitButton digitButton[]=new MyDigitButton[digitButtonText.length];  
25MyOperatorButton operatorButton[]=new MyOperatorButton[operatorButtonText.length];  
26MyMemoryButton memoryButton[]=new MyMemoryButton[memoryButtonText.length];  
27MySpecialButton specialButton[]=new MySpecialButton[specialButtonText.length];  
28  
29Label displayLabel=new Label("0",Label.RIGHT);  
30Label memLabel=new Label(" ",Label.RIGHT);  
31  
32final int FRAME_WIDTH=325,FRAME_HEIGHT=325;  
33final int HEIGHT=30, WIDTH=30, H_SPACE=10,V_SPACE=10;  
34final int TOPX=30, TOPY=50;  
35///////////////////////////  
36MyCalculator(String frameText)//constructor  
37{  
38super(frameText);  
39  
40int tempX=TOPX, y=TOPY;  
41displayLabel.setBounds(tempX,y,240,HEIGHT);  
42displayLabel.setBackground(Color.BLUE);  
43displayLabel.setForeground(Color.WHITE);  
44add(displayLabel);  
45  
46memLabel.setBounds(TOPX,  TOPY+HEIGHT+ V_SPACE,WIDTH, HEIGHT);  
47add(memLabel);  
48  
49// set Co-ordinates for Memory Buttons  
50tempX=TOPX;   
51y=TOPY+2*(HEIGHT+V_SPACE);  
52for(int i=0; i<memoryButton.length; i++)  
53{  
54memoryButton[i]=new MyMemoryButton(tempX,y,WIDTH,HEIGHT,memoryButtonText[i], this);  
55memoryButton[i].setForeground(Color.RED);  
56y+=HEIGHT+V_SPACE;  
57}  
58  
59//set Co-ordinates for Special Buttons  
60tempX=TOPX+1*(WIDTH+H_SPACE); y=TOPY+1*(HEIGHT+V_SPACE);  
61for(int i=0;i<specialButton.length;i++)  
62{  
63specialButton[i]=new MySpecialButton(tempX,y,WIDTH*2,HEIGHT,specialButtonText[i], this);  
64specialButton[i].setForeground(Color.RED);  
65tempX=tempX+2*WIDTH+H_SPACE;  
66}  
67  
68//set Co-ordinates for Digit Buttons  
69int digitX=TOPX+WIDTH+H_SPACE;  
70int digitY=TOPY+2*(HEIGHT+V_SPACE);  
71tempX=digitX;  y=digitY;  
72for(int i=0;i<digitButton.length;i++)  
73{  
74digitButton[i]=new MyDigitButton(tempX,y,WIDTH,HEIGHT,digitButtonText[i], this);  
75digitButton[i].setForeground(Color.BLUE);  
76tempX+=WIDTH+H_SPACE;  
77if((i+1)%3==0){tempX=digitX; y+=HEIGHT+V_SPACE;}  
78}  
79  
80//set Co-ordinates for Operator Buttons  
81int opsX=digitX+2*(WIDTH+H_SPACE)+H_SPACE;  
82int opsY=digitY;  
83tempX=opsX;  y=opsY;  
84for(int i=0;i<operatorButton.length;i++)  
85{  
86tempX+=WIDTH+H_SPACE;  
87operatorButton[i]=new MyOperatorButton(tempX,y,WIDTH,HEIGHT,operatorButtonText[i], this);  
88operatorButton[i].setForeground(Color.RED);  
89if((i+1)%2==0){tempX=opsX; y+=HEIGHT+V_SPACE;}  
90}  
91  
92addWindowListener(new WindowAdapter()  
93{  
94public void windowClosing(WindowEvent ev)  
95{System.exit(0);}  
96});  
97  
98setLayout(null);  
99setSize(FRAME_WIDTH,FRAME_HEIGHT);  
100setVisible(true);  
101}  
102//////////////////////////////////  
103static String getFormattedText(double temp)  
104{  
105String resText=""+temp;  
106if(resText.lastIndexOf(".0")>0)  
107    resText=resText.substring(0,resText.length()-2);  
108return resText;  

1/* Create Switch cases */
2Scanner sc= new Scanner(System.in);
3int firstNum= sc.nextInt();
4int secondNum= sc.nextInt();
5System.out.println("Enter an operator (+, -, *, /):");
6char operator= sc.next().chartAt(0);
7double result=0;
8switch(operator){
9  case "+":
10    result+= firstNum+ secondNum;
11    break;
12  case "-":
13    result+= firstNum-secondNum;
14    break;
15  case "*":
16    result+= firstNum*secondNum;
17    break;
18  case "/":
19    result+= firstNum/secondNum;
20    break;
21}

1package main;
2
3import java.util.Scanner;
4
5public class calculator {
6
7    public static void greetings(){
8        System.out.println("Hi welcome to the calculator made by Pepa pig made in java! :D");
9    }
10
11    public static void instruction(){
12        System.out.println("Hi welcome to the calculator made by Pepa pig made in java! :D");
13    }
14
15    public static void calculator(){
16        Scanner keyboardInput = new Scanner(System.in);
17        String calculator;
18
19        do {
20            System.out.print("Enter your first digit: ");
21            double num1 = keyboardInput.nextDouble();
22
23            System.out.print("Enter your operator: ");
24            String op = keyboardInput.next();
25
26            System.out.print("Enter your second digit: ");
27            double num2 = keyboardInput.nextDouble();
28
29            System.out.print("= ");
30
31            if (op.equals("+")){
32                System.out.print(num1 + num2);
33                System.out.println("\nYou were adding");
34                System.out.println("How I know that cause I have big brain and a smart programmer ;)");
35            }else if (op.equals("-")){
36                System.out.print(num1 - num2);
37                System.out.println("\nYou were subtracting");
38                System.out.println("How I know that cause I have big brain and a smart programmer ;)");
39            }else if (op.equals("*")){
40                System.out.print(num1 * num2);
41                System.out.println("\nYou were multiplying");
42                System.out.println("How I know that cause I have big brain and a smart programmer ;)");
43            }else if (op.equals("/")){
44                System.out.print(num1 / num2);
45                System.out.println("\nYou were dividing");
46                System.out.println("How I know that cause I have big brain and a smart programmer ;)");
47            }else if (op.equals("%")){
48                System.out.print(num1 % num2);
49                System.out.println("\nYou were remanding");
50                System.out.println("How I know that cause I have big brain and a smart programmer ;)");
51            }else{
52                System.out.println("Invalid operator");
53            }
54            System.out.print("Would you like to restart the calculator? (y or n): ");
55            calculator = keyboardInput.next();
56        }
57        while (calculator.equals("y"));
58
59        if (calculator.equals("n")){
60            System.out.println("Leave then kiddo ;-;");
61        }
62    }
63
64
65    public static void main(String[] args) {
66        greetings();
67        instruction();
68        calculator();
69    }
70}

1import java.util.Scanner;
2
3public class Calculator {
4
5    public static void main(String[] args) {
6
7        Scanner reader = new Scanner(System.in);
8        System.out.print("Enter two numbers: ");
9
10        // nextDouble() reads the next double from the keyboard
11        double first = reader.nextDouble();
12        double second = reader.nextDouble();
13
14        System.out.print("Enter an operator (+, -, *, /): ");
15        char operator = reader.next().charAt(0);
16
17        double result;
18
19        switch(operator)
20        {
21            case '+':
22                result = first + second;
23                break;
24
25            case '-':
26                result = first - second;
27                break;
28
29            case '*':
30                result = first * second;
31                break;
32
33            case '/':
34                result = first / second;
35                break;
36
37            // operator doesn't match any case constant (+, -, *, /)
38            default:
39                System.out.printf("Error! operator is not correct");
40                return;
41        }
42
43        System.out.printf("%.1f %c %.1f = %.1f", first, operator, second, result);
44    }
45}