JTextArea的前景颜色不会改变

Question

我试着把这个transcluentJTextArea的前景色改成黑色，但仍然是蓝灰色。我做错了什么？

    // [8]*HELP TEXTAREA
    JTextArea help_text = new JTextArea () {
        @Override
        protected void paintComponent(Graphics g) {
            Graphics2D g2d = (Graphics2D) g;
            Insets insets = getInsets();
            int x = insets.left;
            int y = insets.top;
            int width = getWidth() - (insets.left + insets.right);
            int height = getHeight() - (insets.top + insets.bottom);
            g2d.setColor(new Color(255, 0, 0, 70));
            g2d.fillRect(x, y, width, height);
            super.paintComponent(g);
        }
    };
    help_text.setFont(new Font(Font.MONOSPACED,Font.BOLD, 70));
    help_text.setForeground(Color.black);
    help_text.setOpaque(false);
    help_text.setLineWrap(true);
    help_text.setWrapStyleWord(true);
    help_text.setEditable(false);
    help_text.setEnabled(false);
    help_text.setHighlighter(null); 
    help_text.setText("Some help text . ..");
    // [8]*HELP PANE
    JScrollPane help_pane = new JScrollPane(help_text);
    help_pane.setOpaque(false);
    help_pane.getViewport().setOpaque(false);  

Answer 1

改变：

@Override
protected void paintComponent(Graphics g) {
    Graphics2D g2d = (Graphics2D) g;
    Insets insets = getInsets();
    int x = insets.left;
    int y = insets.top;
    int width = getWidth() - (insets.left + insets.right);
    int height = getHeight() - (insets.top + insets.bottom);
    g2d.setColor(new Color(255, 0, 0, 70));
    g2d.fillRect(x, y, width, height);
    super.paintComponent(g);
}

进入：

@Override
protected void paintComponent(Graphics g) {
    super.paintComponent(g);

    Graphics2D g2d = (Graphics2D) g.create();

    Insets insets = getInsets();
    int x = insets.left;
    int y = insets.top;
    int width = getWidth() - (insets.left + insets.right);
    int height = getHeight() - (insets.top + insets.bottom);
    g2d.setColor(new Color(255, 0, 0, 70));
    g2d.fillRect(x, y, width, height);

    g2d.dispose();
}

我相信这会解决你的问题，因为从你的代码来看，它有两个潜在的问题：

• 通过调用super.paintComponent（g）作为代码的最后一行，您取消了所有正在进行的绘制
• 您正在更改接收的Graphics对象的状态，该对象由整个组件层次结构使用，并且应该保留哪个状态