Java Runtime on MAC

Hello
I have a java swing application and one button that open CharacterPallete.app (native Mac CharacterMap)
The code looks like that:

Code:

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String[] argument = new String[] {"open","/System/Library/Input Methods/CharacterPalette.app"};
Runtime.getRuntime().exec(argument);

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When i push the button CharacterPallete appear but cannot insert any char to any editor (works only on DragAndDrop)
Any idea how can i solve it?
Thanks