Basic calculator in Java

Question

I m trying to create a basic calculator in Java  I m quite new to programming so I m trying to get used to it    import java util Scanner  import javax swing JOptionPane   public class javaCalculator         public static void main String   args                 int num1          int num2          String operation            Scanner input   new Scanner System in            System out println  please enter the first number            num1   input nextInt             System out println  please enter the second number            num2   input nextInt             Scanner op   new Scanner System in            System out println  Please enter operation            operation   op next             if  operation                                System out println  your answer is     num1   num2                      if   operation     -                          System out println  your answer is     num1 - num2                       if  operation                                System out println  your answer is     num1   num2                      if  operation                               System out println  your answer is     num1   num2                          This is my code  It prompts for the numbers and operation  but displays the answers all together

User · Answer

import java util Scanner  public class AdditionGame    public static void main String   args           TODO Auto-generated method stub      int num1      int num2      String operation       Scanner input   new Scanner System in        System out println  Please Enter The First Number        num1   input nextInt         System out println  Please Enter The Second Number        num2   input nextInt         Scanner op   new Scanner  System in        System out println  Please Enter The Operation        operation   op next         if  operation equals                     System out println  Your Answer is    num1   num2              else if  operation equals  -                  System out println  Your Answer is    num1 - num2                     else if  operation equals                     System out println  Your Answer is    num1   num2                 else if  operation equals                     System out println  Your Answer is    num1   num2

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public class SwitchExample        public static void main String   args  throws Exception           System out println                       Start                               System out println   n n             System out println  1  Addition            System out println  2  Multiplication            System out println  3  Substraction            System out println  4  Division            System out println  0  Exit            System out println   n             System out println  Enter Your Choice                      BufferedReader br   new BufferedReader new InputStreamReader System in            String str   br readLine             int usrChoice   Integer parseInt str            switch  usrChoice                case 1                  doAddition                    break              case 2                  doMultiplication                    break              case 3                  doSubstraction                    break              case 4                  doDivision                    break               case 0                  System out println  Thank you                         break               default                  System out println  Invalid Value                       System out println                       End                          public static void doAddition   throws Exception       System out println          Enter in Addition Process                  String strNo1  strNo2       System out println  Enter Number 1 For Addition           BufferedReader br   new BufferedReader new InputStreamReader System in        strNo1   br readLine         System out println  Enter Number 2 For Addition           BufferedReader br1   new BufferedReader new InputStreamReader System in        strNo2   br1 readLine         int no1   Integer parseInt strNo1       int no2   Integer parseInt strNo2        int result   no1   no2       System out println  Addition of     no1     and     no2     is             result      public static void doSubstraction   throws Exception       System out println          Enter in Substraction Process                  String strNo1  strNo2       System out println  Enter Number 1 For Substraction           BufferedReader br   new BufferedReader new InputStreamReader System in        strNo1   br readLine         System out println  Enter Number 2 For Substraction           BufferedReader br1   new BufferedReader new InputStreamReader System in        strNo2   br1 readLine         int no1   Integer parseInt strNo1       int no2   Integer parseInt strNo2        int result   no1 - no2       System out println  Substraction of     no1     and     no2     is             result      public static void doMultiplication   throws Exception       System out println          Enter in Multiplication Process                  String strNo1  strNo2       System out println  Enter Number 1 For Multiplication           BufferedReader br   new BufferedReader new InputStreamReader System in        strNo1   br readLine         System out println  Enter Number 2 For Multiplication           BufferedReader br1   new BufferedReader new InputStreamReader System in        strNo2   br1 readLine         int no1   Integer parseInt strNo1       int no2   Integer parseInt strNo2        int result   no1   no2       System out println  Multiplication of     no1     and     no2     is             result      public static void doDivision   throws Exception       System out println          Enter in Dividion Process                  String strNo1  strNo2       System out println  Enter Number 1 For Dividion           BufferedReader br   new BufferedReader new InputStreamReader System in        strNo1   br readLine         System out println  Enter Number 2 For Dividion           BufferedReader br1   new BufferedReader new InputStreamReader System in        strNo2   br1 readLine         int no1   Integer parseInt strNo1       int no2   Integer parseInt strNo2        float result   no1   no2       System out println  Division of     no1     and     no2     is             result

User · Answer

Java program example for making a simple Calculator   import java util Scanner   public class Calculator   public static void main String args          float a  b  res      char select  ch      Scanner scan   new Scanner System in        do               System out print   1  Addition n            System out print   2  Subtraction n            System out print   3  Multiplication n            System out print   4  Division n            System out print   5  Exit n n            System out print  Enter Your Choice               choice   scan next   charAt 0            switch select                        case  1    System out print  Enter Two Number                       a   scan nextFloat                    b   scan nextFloat                    res   a   b                  System out print  Result       res                   break              case  2    System out print  Enter Two Number                       a   scan nextFloat                    b   scan nextFloat                    res   a - b                  System out print  Result       res                   break              case  3    System out print  Enter Two Number                       a   scan nextFloat                    b   scan nextFloat                    res   a   b                  System out print  Result       res                   break              case  4    System out print  Enter Two Number                       a   scan nextFloat                    b   scan nextFloat                    res   a   b                  System out print  Result       res                   break              case  5    System exit 0                   break              default   System out print  Wrong Choice                      while choice    5

User · Answer

maybe its better using the  case instead of if dunno if this eliminates the error  but its cleaner i think   switch  operation  case    System out println  your answer is     num1   num2   break case -  System out println  your answer is  -  num1 - num2   break

User · Answer

Remove the semi-colons from your if statements  otherwise the code that follows will be free standing and will always execute   if  operation                                   Also use  equals for Strings     compares Object references    if  operation equals

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import java util Scanner  import javax swing JOptionPane   public class javaCalculator     public static void main String   args         int num1      int num2      String operation        Scanner input   new Scanner System in        System out println  please enter the first number        num1   input nextInt         System out println  please enter the second number        num2   input nextInt         Scanner op   new Scanner System in        System out println  Please enter operation        operation   op next         if  operation equals                     System out println  your answer is     num1   num2             else if   operation equals  -                  System out println  your answer is     num1 - num2             else if  operation equals                     System out println  your answer is     num1   num2             else if  operation equals                     System out println  your answer is     num1   num2             else               System out println  Wrong selection

User · Answer

Here is simple code for calculator so you can consider this import java util    import java util Scanner  public class Hello       public static void main String   args                System out println  Enter first and second number             Scanner inp  new Scanner System in           int num1 num2          num1   inp nextInt            num2   inp nextInt            int ans          System out println  Enter your selection  1 for Addition  2 for substraction 3 for Multiplication and 4 for division             int choose          choose   inp nextInt            switch  choose           case 1              System out println add  num1 num2                break          case 2              System out println sub  num1 num2                break                case 3              System out println mult  num1 num2                break          case 4              System out println div  num1 num2                break              default                  System out println  Illigal Operation                             public static int add int x  int y                int result   x   y          return result            public static int sub int x  int y                int result   x-y          return result            public static int mult int x  int y                int result   x y          return result            public static int div int x  int y                int result   x y          return result

User · Answer

we can simply use  in next   charAt 0   to assign   -     operations as  characters by initializing           operation as a char   import java util    public class Calculator    public static void main String   args     Scanner in   new Scanner System in    char operation  int num1  int num2    System out println  Enter First Number     num1   in nextInt     System out println  Enter Operation     operation   in next   charAt 0    System out println  Enter Second Number     num2   in nextInt     if  operation          make sure single quotes       System out println  your answer is      num1   num2      if  operation     -         System out println  your answer is      num1 - num2      if  operation               System out println  your answer is      num1   num2      if  operation               System out println  your answer is      num1   num2

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import java util Scanner  public class JavaApplication1         public static void main String   args              int x           int y            Scanner input new Scanner System in            System out println  Enter Number 1             x input nextInt             System out println  Enter Number 2             y input nextInt              System out println  Please enter operation   -   or               Scanner op new Scanner System in            String operation   op next              if  operation equals                     System out println  Your Answer       x y                        if  operation equals  -                  System out println  Your Answer      x-y                        if  operation equals                     System out println  Your Answer      x y                        if  operation equals                    System out println  Your Answer      x y

User · Answer

CompareStrings with equals     not with     if  operation equals            System out println  your answer is     num1   num2      if  operation equals  -          System out println  your answer is     num1 - num2      if  operation equals             System out println  your answer is     num1   num2      if  operation  equals              System out println  your answer is     num1   num2        And the   after the conditions was an empty statement so the conditon had no effect at all   If you use java 7 you can also replace the if statements with a switch  In java  lt 7 you can test  if operation has length 1 and than make a switch for the char  switch  operation charAt 0

[java] Basic calculator in Java

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