JButton background color from slider

I have a JPanel to allow the user to set the color of an object with these components:

• TextField (R)
• TextField (G)
• TextField (B)

• Slider (Opacity 1-100)

• 开发者_运维技巧Button (preview of color using values from above elements)

What I'm asking is why the button get the color correctly but not the opacity.

Here's my code:

public Color getColor() {
    if (tfRed.getText().equals("") || tfGreen.getText().equals("") || tfBlue.getText().equals("")) {
            return new Color(0, 0, 0, 0);
    } else {
        if (tfRed.getText().matches("\\d+") && tfGreen.getText().matches("\\d+") && tfBlue.getText().matches("\\d+")
                && Integer.parseInt(tfRed.getText()) <= 255 && Integer.parseInt(tfGreen.getText()) <= 255 && Integer.parseInt(tfBlue.getText()) <= 255
                && Integer.parseInt(tfRed.getText()) >= 0 && Integer.parseInt(tfGreen.getText()) >= 0 && Integer.parseInt(tfBlue.getText()) >= 0) {
             return new Color(
                    Float.parseFloat(tfRed.getText()) / 255,
                    Float.parseFloat(tfGreen.getText()) / 255,
                    Float.parseFloat(tfBlue.getText()) / 255, 
                    Float.parseFloat(sOpacity.getValue() + "") / 100
                    );
        } else {
            JOptionPane.showMessageDialog(this, "Invalid rgb value");
            tfRed.setText("0");
            tfGreen.setText("0");
            tfBlue.setText("0");
            return new Color(0, 0, 0, 0);
        }
    }
}

I set the color of the button in a single event for all textfield and another event for the slider:

// on keyup
private void button_color(java.awt.event.KeyEvent evt) {
    bColor.setBackground(getColor());
}

// on mousedragged and mouseclicked
private void slider_value(java.awt.event.MouseEvent evt) {
    lOpacity.setText(sOpacity.getValue() + "");
    bColor.setBackground(getColor());
}

I debugged it and I saw that the color taken from getColor() returns only rgb values w/o opacity, but when I use getColor() with other custom components it works (rgb + opacity). Thanks for help

EDIT

Found solution:

// on mousedragged and mouseclicked
private void slider_value(java.awt.event.MouseEvent evt) {
    lOpacity.setText(sOpacity.getValue() + "");
    bColor.setBackground(getColor());  
    bColor.getParent().repaint();  <------
}

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I do not think setting button's background color is useful, JButton's background color set by look and feel, it's hard to change the button's color, use JLabel instead