No curly brace alternative and a warning.

You can have an if and the else if and else statement without and with curly braces. Without curly braces is considered a shortcut when only the next line is controlled. Generally you should indent the single line or place it on the same line as the if, else if or else statement with the former preferred. Here is an example where the if, the else and else if only control one line of code using the preferred styling.

if ( test expression )

   ____________________;  // The single line of code

                          // controlled by the if statement

// DO NOT PUT CODE HERE - COMPILER ERROR!

else if ( test expression )

   ____________________;  // The single line of code

                          // controlled by the else if statement

                          // skipped if previous test

                          // expressions are true

// DO NOT PUT CODE HERE - COMPILER ERROR!

else if ( test expression )

   ____________________;  // The single line of code

                          // controlled by the else if statement

                          // skipped if previous test

                          // expressions are true

// DO NOT PUT CODE HERE - COMPILER ERROR!

else 

   ___________________;   // The single line of code

                          // controlled by the else statement

____________________;     // This line of code executes

                          // independently of the

                          // else statement and regardless

                          // if you indent it.

 

One danger is placing additional lines after the line controlled by the if statement an before the else if statement. This fortunately will result in a compiler error and you need to either move the line or add curly braces.

 

Another danger is that if you add another line later during programming you wanted controlled by the last else if statement, you may overlook that the line is not part of the else statement. This leads to the more difficult to solve logic type of bug.

 

Beginners and most programmers should always include curly braces for both the if and the else if statements.

import javax.swing.*;

public class Tester
{
   // Fields (Always static in main method of starting class)
   static float annualSalary;      // Current annual salary
                                   // .01 - 1000000.00
                                   // 0 not valid or unchanged
  
   public static void main(String[]args)
   {
      float percentIncrease;       // Set based on salary ranges
                                   // -0 not valid or unchangedd
                                   // .05          0.01  -   49999.00
                                   // .045     50000.00  -   74999.00
                                   // .0425    75000.00  -   99999.00
                                   // .04     100000.00  -  499999.00
                                   // .06     500000.00  - 1000000.00
      // Prompt and get annualSalary
      inputAnnualSalary();

 

      // annualSalary is from .01      to 49999.0
      if (annualSalary >= 0.01          && annualSalary <= 49999.0)
      {
         percentIncrease = 0.05f;
      }
      // annualSalary is from 50000.0  to 74999.0
      else if (annualSalary >= 50000.0  && annualSalary <  75000.0)
      {
         percentIncrease = 0.045f;
      }
      // annualSalary is from 75000.0  to 99999.0
      else if (annualSalary >= 75000.0  && annualSalary <  100000.0)
      {
         percentIncrease = 0.0425f;
      }
      // annualSalary is from 100000.0 to 499999.0
      else if (annualSalary >= 100000.0 && annualSalary <  500000.0)
      {
         percentIncrease = 0.04f;
      }
      // annualSalary is from 500000.0 to 1000000
      else if (annualSalary >= 500000.0 && annualSalary <= 1000000.0)
      {
         percentIncrease = 0.06f;
      }
      else
      {
         percentIncrease = 0;
      }

 

      // A salary .01 - 1000000 was entered
      if (percentIncrease != 0)
      {
         // Display old salary
         System.out.println("Your old salary is  "  +  annualSalary );
         // Compute new salary
         annualSalary *= 1.0 + percentIncrease ;
         // Display new percentage change a whole percent and new salary 
         System.out.println("Percent increase is " + ( percentIncrease * 100 )
                                                   + "%");
         System.out.println("Your new salary is  "  + annualSalary );
      }
   }

 

   static void inputAnnualSalary()
   {
      String returnValue;              // showInputDialog return value
      String prompt;                   // showInputDialog prompt argument
      String title;                    // showInputDialog title argument
      int msgTypeQ =
         JOptionPane.QUESTION_MESSAGE; // showInputDialog message type
                                       // in variable to shorten code
      annualSalary = 0;                // 0 not valid or unchanged
      // Prompt and get annual salary
      prompt = "Enter your annual salary";
      title  = "Attention";
      returnValue = JOptionPane.showInputDialog(null, prompt, title, msgTypeQ);
      // Salary was entered - convert to float
      if (returnValue != null && !returnValue.equals(""))
      {
         // Convert returnValue to float
         annualSalary = Float.parseFloat(returnValue);
         // annualSalary is not from .01 to 1000000.00
         if ( annualSalary < 0.01 || annualSalary > 1000000.00 )
         {
            System.out.println("Salary entered was not from 0.01 to 1000000.00.");
            annualSalary = 0;          // Set to failed value
         }
      }
      // Nothing entered
      else
      {
         System.out.println("Salary was not entered");
      }
   }
}