GUI 怎么设置新建窗口的默认焦点

给textarea增加一个鼠标单击事件，单击时将输入焦点定位到textfield

 final JTextField txtf = new JTextField();
        txtf.setColumns(10);
        JTextArea txta = new JTextArea();
        txta.setText("slfsdfjldsfsdfjlsdfjdslj");
        txta.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                txtf.requestFocus();
            }
        });