集中组件参考 [英] focused component reference

问题描述

我正在研究一个简单的基于Java swing的应用程序。我将如何获取和设置表单的当前焦点文本字段/文本区域的文本？

我知道如何确定哪个组件具有焦点，但我无法弄清楚如何获取组件的选定文本。我使用getFocusOwner（），但它返回一个组件，因此不实现方法getSelectedText（）。我是否需要做一个类型转换？

解决方案根据您的确切上下文，您可能会考虑使用自定义的TextAction：其方法 getTextComponent ActionEvent）返回最近的焦点文本组件。代码片段：

 操作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））; 
  

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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