CODEWITHSUNDEEP
javaif-statementoptimizationswitch-statement
Character
Character

Reputation: 23

Java If-else structure optimization

anyone has ideas about making this block of if-else statements simpler other than purely using switch-case statements? Thanks for your time!

public void onButtonClick(int type, int state) { 
        if (type == 1) {
            if (state == 1)                            
                jsonDataToString(); // method 1
            else if (state == 2)
                filterRecordFile(); // method 2
            else if (state == 3)
                filterResourceFile(); // method 3
        } else if (type == 2) { 
            if (state == 1)
                jsonDataToString(); // method 1
            else if (state == 2)
                filterHasBackup(); // method 4
            else if (state == 3)
                filterNotBackup(); // method 5
        } else if (type == 3) { 
            if (state == 1)
                jsonDataToString(); // method 1
            else if (state == 2)
                filterOverSize(); // method 6
            else if (state == 3)
                filterDownSize(); // method 7
        } 
    }

Upvotes: 2

Views: 155

Answers (4)

Character
Character

Reputation: 23

thanks for your help. Here I found a great and detailed explanation: https://programmer.help/blogs/java-optimization-28-optimizing-if-else-writing.html

His blog gives 8 optimization schemes to optimize if-else writing. I leave it here for late-comers :-)

Upvotes: 0

f_puras
f_puras

Reputation: 2505

I would factor out the state handling and convert it to switches, like:

public void onButtonClick(int type, int state) {
    if (type == 1) {
        handleTypeOne(state);
    } else if (type == 2) {
        handleTypeTwo(state);
    }
}

private void handleTypeOne(int state) {
    switch(state) {
        case 1:
            jsonDataToString(); // method 1
            break;
        case 2:
            filterRecordFile(); // method 2
            break;
        case 3:
            filterResourceFile(); // method 3
            break;
        default:
            break;
    }
}

private void handleTypeTwo(int state) {
    switch(state) {
        case 1:
            jsonDataToString(); // method 1
            break;
        case 2:
            filterHasBackup(); // method 4
            break;
        case 3:
            filterNotBackup(); // method 5
            break;
        default:
            break;
    }
}

This allows you to choose more meaningful method names than I did. Besides (and unrelated to your question), I would recommend to introduce constants for the state values in order to make the case selections more comprehensible.

Upvotes: 1

George
George

Reputation: 338

If you just want to make your code easier to read, you could try to format it differently by combining both conditions. Although you have to write type == 1 multiple times, it reduces the amount of nested if statements, which makes the code more readable.

public void onButtonClick(int type, int state) { 
    if (type == 1 && state == 1) jsonDataToString();
    if (type == 1 && state == 2) filterRecordFile();                       
    if (type == 1 && state == 3) filterResourceFile();
    if (type == 2 && state == 1) jsonDataToString();
    if (type == 2 && state == 2) filterHasBackup();
    if (type == 2 && state == 3) filterNotBackup();
}

Upvotes: 1

Alexander Alexandrov
Alexander Alexandrov

Reputation: 1362

You can use tabular functions for such handlers. For example:

class Main {
  private static final Runnable[][] HANDLERS_TABLE = {
    { Main::jsonDataToString, Main::filterRecordFile, Main::filterResourceFile },
    { Main::jsonDataToString, Main::filterHasBackup, Main::filterNotBackup }
  };

  private static void jsonDataToString() {
    System.out.println("Hello jsonDataToString!");
  }

  private static void filterRecordFile() {
    System.out.println("Hello filterRecordFile!");
  }

  private static void filterResourceFile() {
    System.out.println("Hello filterResourceFile!");
  }

  private static void filterHasBackup() {
    System.out.println("Hello filterHasBackup!");
  }

  private static void filterNotBackup() {
    System.out.println("Hello filterNotBackup!");
  }

  public static void onButtonClick(int type, int state) { 
    HANDLERS_TABLE[type][state].run();
  }

  public static void main(String[] args) {
    onButtonClick(1, 1);
  }
}

https://replit.com/join/yzjqwikvil-redneckz

Also, it makes sense to use enums for keys. For example:

enum HandlerType {
  FIRST, SECOND
}

public static void onButtonClick(HandlerType type, int state) { 
    HANDLERS_TABLE[type.ordinal()][state].run();
}

Upvotes: 1

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