如何回到 Java 中的 JFrame [英] How to go back to a JFrames in Java

问题描述

我在 JFrame 中有一个按钮，如果按下它，它会将我们带到另一个框架.我使用了这段代码:

I have a button in a JFrame, if pressed, it takes us to another frame. I used this code:

private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {

    SecondForm secondform = new SecondForm();
    secondform.setVisible(true);
    setVisible(false);
    dispose();
    }

所以新框架打开并且一切正常.然后我在第二帧中放置了另一个按钮，以便返回上一帧.我使用了这段代码:

So the new frame opens and everything is ok. Then i placed another button -in the second frame- in order to go back to the previous frame. I used this code:

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         

    MainForm Mform = new MainForm();
    Mform.setVisible(true);
    setVisible(false);
    dispose();
}                                        

问题是，我认为这不是正确的做法.我想要的是:

The thing is, i don't think this is the right way to do this. What i want is to:

• 隐藏第一帧
• 显示新的第二个
• 处理第二个
• 再次显示第一个

有没有办法使用第一个 MainForm 实例而不是每次我想返回时都创建一个新实例.我监控了我的程序，每次我来回切换帧时，正如我所怀疑的那样，它使用的内存不断增加.

Is there a way to do that using the first MainForm instance and not creating a new one every time i want to go back. I monitored my program and every time i go back and forth the frames and as i suspected, the ram being used by it keeps increasing.

提前致谢.

我有一个登录系统，当用户输入正确的凭据时，就会创建一个新的 ManiForm 实例.

EDIT : I have a login system and when the user put the correct credentials a new ManiForm instance is created.

MainForm Mform = new MainForm();
Mform.setVisible(true);

这就是我要使用的实例.ii 有没有办法让 MForm 从 secondform 再次可见?

That is the instance i want to use. Ii there a way to make MForm visible again from the secondform?

首先感谢您的帮助！

我同意不使用多个 JFrame 会更容易，但你能告诉我哪种方法更好地完成我在第一篇文章中提出的要求吗?Robin 给我的答案非常好，但我不知道该放什么作为论据*:

I agree that it is easier not to use more than one JFrames, but can you please tell me which is the better way to do what i asked in the first post? The answer Robin gave me is very nice but i don't know what to put as an argument there*:

java.awt.EventQueue.invokeLater(new Runnable() {

        public void run() {
    *   new SecondForm().setVisible(true);
        }
    });

它来自 NetBeans 自动生成的代码.

It's from the auto-generated code from NetBeans.

我试过了

new SecondForm(super).setVisible(true);

但我仍然得到编译错误.显然我必须放 super.something() 但我不知道是什么.我尝试了很多，但没有成功.

but i still get compile errors. Apparently i must put super.something() but i don't know what. I tried many but no luck.

推荐答案

你不应该使用超过一帧.

you shouldn't use more then one frame.

除了 defaultExitOperation、size、preferedsize 和 visible true 之外，您应该在 JFrame 中没有任何内容.而是将所有按钮和字段放入 JPanel 中，然后在 JFrame 中添加/删除 JPanel.

You should have NOTHING in JFrame except defaultExitOperation, size, preferedsize and visible true. Instead place all buttons and fields into a JPanel and add/remove the JPanel from the JFrame.

如果您想打开另一个窗口，请使用 JDialog.

If you want another Window open use JDialog.

顺便说一句:您可以将 MainFrame 设置为 false 并以 MainFrame 作为父级打开一个 JDialog.只有当有人写下正确的用户 + 密码时，您才能使 MainFrame 可见.

btw: you can have your MainFrame setVisible false and open a JDialog with your MainFrame as parent. Only if someone writes down the right user + password you make the MainFrame visible.

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