如何检查JFrame Existense

Question

我想创建一个带有函数的jbutton来调用jframe，但是jbutton必须能够停止调用jframe，如果它已经被调用并存在的话。我们怎么能这样做？

    JButtonCallJFrame.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {

        //step 1 - check if jframe already open/called or not

        //step 1.a - if true ignore, jbutton do nothing

        //step 1.2 - else if false,jbutton called for jframe

        ClassWithJFrame cwjFrame = new ClassWithJFrame()
        if(cwjFrame is exist){

          //DO NOTHING
        }
        else if(cwjFrame not exist){

         cwjFrame.setVisible(true);
        }
        }
    });

Answer 1

使用jframe.isVisible()

cwjFrame.isVisible() will return true if frame is already visible 

if(cwjFrame.isVisible()){

      //DO NOTHING
 }
else if(!cwjFrame.isVisible()){

     cwjFrame.setVisible(true);

}