When should we write 'return' and when should we not?

Question

My code here won't work because I wrote return at my line number 12 and 14. If I omit the 'return', I should be good. My question is, when are we supposed to write 'return' and when are we supposed not to?

ConferenceRegistrationAssistant.java

public class ConferenceRegistrationAssistant {

  /**
   * Assists in guiding people to the proper line based on their last name.
   *
   * @param lastName The person's last name
   * @return The line number based on the first letter of lastName
   */
  public int getLineNumberFor(String lastName) {
    int lineNumber = 0;
    if (lastName.charAt(0) <= 'M' {
      return lineNumber = 1;
    } else {
      return lineNumber = 2;
      }
    /*
      lineNumber should be set based on the first character of the person's last name
      Line 1 - A thru M
      Line 2 - N thru Z

     */
    return lineNumber;
  }

}

Example.java

public class Example {

  public static void main(String[] args) {
    /*
      IMPORTANT:  You can compare characters using <, >. <=, >= and == just like numbers
     */
    if ('C' < 'D') {
      System.out.println("C comes before D");
    }

    if ('B' > 'A') {
      System.out.println("B comes after A");
    }

    if ('E' >= 'E') {
      System.out.println("E is equal to or comes after E");
    }

    // This code is here for demonstration purposes only...
    ConferenceRegistrationAssistant assistant = new ConferenceRegistrationAssistant();
    /*
      Remember that there are 2 lines.
      Line #1 is for A-M
      Line #2 is for N-Z
     */
    int lineNumber = 0;
    /*
      This should set lineNumber to 2 because
      The last name is Zimmerman which starts with a Z.
      Therefore it is between N-Z
     */
    lineNumber = assistant.getLineNumberFor("Zimmerman");

    /*
      This method call should set lineNumber to 1, because 'A' from "Anderson" is between A-M.
     */
    lineNumber = assistant.getLineNumberFor("Anderson");

    /*
      Likewise Charlie Brown's 'B' is between 'A' and 'M', so lineNumber should be set to 1
     */
    lineNumber = assistant.getLineNumberFor("Brown");
  }

}

Answer 1 · 2017-05-19T19:25:48Z

May 19, 2017 7:25pm

If you want to call a method and get a value back you have to return something at some point.

But the second you call return the function will terminate.

Example;

class Test {
    public static void main(String[] args) {
        System.out.println(multiply(2, 3));
    }

    private static int multiply(int a, int b) {
        return 10; //The method will end here because return was called. We have to remove this for it to work

        return a*b // We will never get here because of the return above. ;
    }
}

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Wan Nor Adzahari Wan Tajuddin

Wan Nor Adzahari Wan Tajuddin

When should we write 'return' and when should we not?

1 Answer

Thomas Nilsen

Thomas Nilsen