Detecting Shift modifiers on MouseEvent generated from click in swing

Question

I'm handling some MouseEvent in a GUI application using Java Swing.

Since now i was analyzing mouse events inside mousePressed method, only to determine if a left or right click happened.

My code was:

public void mousePressed(MouseEvent me) {
    if (me.getModifiers == InputEvent.BUTTON1_DOWN_MASK){
     //left click
    }else if (me.getModifiers == InputEvent.BUTTON3_DOWN_MASK){
     //right click
     }

Now my application is becoming more complicated and I need also to check if Shift button was pressed while mouse was left clicking. I would like to do something like this:

public void mousePressed(MouseEvent me) {
    if (me.getModifiers == InputEvent.BUTTON1_DOWN_MASK && me.isShiftDown()){
     //left click
    }

Now this doesn't work. In particular if I click the left button while holding SHIFT isShiftDown returns true (rigth. i was expecting that), but now seems that modifiers are also changed and the comparison with BUTTON1_DOWN_MASK fails.

me.getModifiers == InputEvent.BUTTON1_DOWN_MASK //failed..modifiers are changed

What am I doing wrong? How can I fix my code?

Ernest Friedman-Hill · Accepted Answer · 2011-04-01T19:20:50.393

12

Note that the method is called getModifier_s_(), with an "s", because it can return more than one modifier, combined using bitwise "or". It's technically never correct to use "==": you should use bitwise "&", like this:

if ((me.getModifiers() & InputEvent.BUTTON1_DOWN_MASK) != 0) ...

then you'll respond to that one modifier, even if others are present.

edited Apr 01 '11 at 19:20

answered Apr 01 '11 at 19:13

Ernest Friedman-Hill

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you are right. Anyway your code (me.getModifiers() & InputEvent.BUTTON1_DOWN_MASK) doesn't return a boolean – Heisenbug Apr 01 '11 at 19:19
sorry. I'm a bit confused. Seems to work exactly in the opposite way: (me.getModifiers() & InputEvent.BUTTON1_DOWN_MASK) == 0 . Anyway..you got the point. thanks – Heisenbug Apr 01 '11 at 19:29

score 1 · Answer 2 · edited Oct 11 '16 at 20:46

1

You should use

if ((me.getModifiersEx() & InputEvent.BUTTON1_DOWN_MASK) != 0)

or

if ((me.getModifiers() & InputEvent.BUTTON1_MASK) != 0)

edited Oct 11 '16 at 20:46

Petter Friberg

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answered Oct 11 '16 at 20:34

John Ganci

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Detecting Shift modifiers on MouseEvent generated from click in swing

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