CODEWITHSUNDEEP
javaswitch-statement
John Katsantas
John Katsantas

Reputation: 593

Avoid switch in calculator? - Java

I've just started out on Java and I made a calculator with a GUI which includes this part of code: 

 private void Decider(char c){
    switch (c){
        case '+':
            CalculatorGui.add.operate();
            break;
        case '-':
            CalculatorGui.sub.operate();
            break;`
        case '*':
            CalculatorGui.mul.operate();
            break;
        case '/':
            CalculatorGui.div.operate();
            break;
        default:
            System.out.printf("Invalid\n");
            break;

    }
}

The char c given depends on which button the user clicks on the interface. If he clicks + we get a + if he clicks - we get - etc. Each time I call the method I need from 4 other classes I've made.

My question is: Is there a way to avoid the switch statement?

I suppose I could make one class with one method and depending on what we pass it will do the proper operation. But then I'll have to make a switch statement in there so this leads nowhere.

Upvotes: 1

Views: 124

Answers (1)

janos
janos

Reputation: 124646

You can prepare a map of Runnable:

Map<Character, Runnable> map = new HashMap<>();
map.put('+', () -> CalculatorGui.add.operate());
map.put('-', () -> CalculatorGui.sub.operate());
map.put('*', () -> CalculatorGui.mul.operate());
map.put('/', () -> CalculatorGui.div.operate());

And then use that map to perform the corresponding action, or the default action:

map.getOrDefault(c, () -> System.out.println("Invalid")).run();

Upvotes: 2

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