If statement doesn't execute

Question

I am creating a program that allows you to create a pie chart easily. In the method for removing a slice the if statement inside of a for loop doesnt execute and I cant figure out why this happens. Here is the removeSlice method:

public void removeSlice(Color color, float size, String displayText){
        int num = 0;
        System.out.println("Thing: " + color + " " + size + " " + displayText);
        for(int i = 0; i < slice.size(); i++){
            System.out.println("I: " + slice.get(i).color + " " + slice.get(i).size + " " + slice.get(i).text + " Current: " + i);
            if(slice.get(i).color == color && slice.get(i).size == size && slice.get(i).text.equals(displayText)){
                num = i;
                System.out.println("It Works");
            }
        }
        System.out.println(num);
        slice.remove(slice.get(num));
        totalSize -= size;
        --current;
    }

When trying to remove a slice the console output shows this

Thing: java.awt.Color[r=255,g=255,b=255] 100.0 Hey
I: java.awt.Color[r=0,g=0,b=0] 500.0 Hi Current: 0
I: java.awt.Color[r=255,g=153,b=153] 70.0 Hello Current: 1
I: java.awt.Color[r=255,g=255,b=255] 100.0 Hey Current: 2
I: java.awt.Color[r=153,g=153,b=0] 120.0 Hola Current: 3
0

as you see all of the values equal position 2's values in the ArrayList but still the if statement doesn't execute.

If you aren't using the `Color` constants, you will need to compare with `equals()`. — Sotirios Delimanolis, Oct 08 '13 at 14:32
Related: http://stackoverflow.com/q/513832/1065197. Instead of `String` class, your problem is with `Color` class. — Luiggi Mendoza, Oct 08 '13 at 14:32
@SotiriosDelimanolis you should always use `equals` when comparing object references except for `enum`s since they are singleton. — Luiggi Mendoza, Oct 08 '13 at 14:33

score 4 · Accepted Answer · answered Oct 08 '13 at 14:33

4

You are comparing colors with ==. Use equals instead. == checks if the objects refer to the same place in memory. You create two colors, but with the same content - then, you must use equals to check if the content match.

answered Oct 08 '13 at 14:33

Luan Nico

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Prabhakaran Ramaswamy · Answer 2 · 2013-10-08T14:46:21.263

2

You need to modify slice.get(i).color == color to slice.get(i).color.equals(color).

You should use .equals() method to compare color object.

if(slice.get(i).color.equals(color) && slice.get(i).size == size && slice.get(i).text.equals(displayText)){
                num = i;
                System.out.println("It Works");
            }

edited Oct 08 '13 at 14:46

answered Oct 08 '13 at 14:34

Prabhakaran Ramaswamy

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score 1 · Answer 3 · answered Oct 08 '13 at 14:39

In addition to the == issue for Color, exact equality comparison for float can give problems. It will work if the values being compared were produced by exactly the same calculation, or if all calculations involved are exact. If not, there may be different rounding error leading to a very small difference in values that would be equal in real number arithmetic.

Small integer-valued floats such as 100.0 do represent the integer exactly, so that is probably not your current problem, but it could give you problems with different numbers.

score 0 · Answer 4 · answered Oct 08 '13 at 14:33

0

As a Java Programmer, you should know about equals. Quite often this is what you really want.

answered Oct 08 '13 at 14:33

Waldheinz

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jjmartinez · Answer 5 · 2013-10-08T14:40:41.080

0

try to compare the different values with "equals", no with "=="

edited Oct 08 '13 at 14:40

answered Oct 08 '13 at 14:35

jjmartinez

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score 0 · Answer 6 · answered Oct 08 '13 at 14:35

0

You need to use equals() instead of == for the Color objects.

answered Oct 08 '13 at 14:35

user2793390

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score 0 · Answer 7 · answered Oct 08 '13 at 14:40

It's hard to say because we can't see whole source code but I think that your problem is here "slice.get(i).color == color". With == you tests if both variables reference the same object.

You should consider to use slice.get(i).color.equals(color) and you need to also implement equals, hashCode methods on that object

If statement doesn't execute

7 Answers7