Switch Statement Buggy?

Question

Possible Duplicate:
Switch without break

I am making a small calculator app, and when the calculate button is clicked, a switch statement runs, but the number produced is not what It should be, I have tested my inputs and they do work here is the switch statement:

switch (currentOp) 
{
    case "+" : 
        answer = Float.toString(inp1 + inp2);
    case "-" : 
        answer = Float.toString(inp1 - inp2);
    case "X" : 
        answer = Float.toString(inp1 * inp2);
    case "/" : 
        answer = Float.toString(inp1 / inp2);
}

If you're like me, whenever you think java is "buggy", stop, think again. 99.99% of the time, it's your (or my) understanding of Java that's buggy. Welcome to the club. — Hovercraft Full Of Eels, Dec 25 '12 at 20:59

score 10 · Answer 1 · answered Dec 25 '12 at 20:30

Just an addition to the other answer, using polymorphism is usually preferred to switch cases:

public enum Operation {
    ADDITION {
        @Override
        public float compute(float a, float b) {
            return a + b;
        }
    },
    SUBTRACTION {
        @Override
        public float compute(float a, float b) {
            return a - b;
        }
    },
    PRODUCT {
        @Override
        public float compute(float a, float b) {
            return a * b;
        }
    },
    DIVISION {
        @Override
        public float compute(float a, float b) {
            return a / b;
        }
    };

    public abstract float compute(float a, float b);
}

...

answer = currentOp.compute(inp1, inp2);

I would like to learn this, anyone got any good articles on how to do this? — CodeLover, Dec 25 '12 at 20:50

score 8 · Answer 2 · answered Dec 25 '12 at 20:24

You forgot to break so your case statements are falling through. Try this:

case "+" : answer = Float.toString(inp1 + inp2); break;
case "-" : answer = Float.toString(inp1 - inp2); break;
case "X" : answer = Float.toString(inp1 * inp2); break;
case "/" : answer = Float.toString(inp1 / inp2); break;

Related documentation

The switch statement

score 7 · Accepted Answer · answered Dec 25 '12 at 20:25

See case fallthrough. If you don't break between each case, the next will be executed as well until a break is reached.

The break statements are necessary because without them, statements in switch blocks fall through: All statements after the matching case label are executed in sequence, regardless of the expression of subsequent case labels, until a break statement is encountered.

Switch Statement Buggy?

3 Answers3

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