重点组件参考 [英] focused component reference

问题描述

I am working on a simple java swing based application. How would I get and set the text of the currently focused textfield/textarea of a form?

I know how to determine which component has focus but I can not figure out how I can get the selected text of the component. I use getFocusOwner() but it return a Component and therefore does not implement the method getSelectedText(). Do I somehow need to do a typecast?

解决方案

Depending on your exact context, you might consider to use a custom TextAction: its method getTextComponent(ActionEvent) returns the most recent focused text component. A code snippet:

    Action logSelected = new TextAction("log selected") {

        @Override
        public void actionPerformed(ActionEvent e) {
            JTextComponent text = getTextComponent(e);
            System.out.println("selected: " + text.getSelectedText());
        }

    };

    JComponent content = new JPanel();
    content.add(new JTextField("sometext", 20));
    content.add(new JTextField("other content", 20));
    content.add(new JCheckBox("just some focusable comp"));
    content.add(new JButton(logSelected));

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