BorderLayout中心命令不会居中 [英] BorderLayout center command won't center

问题描述

我试图在 JFrame 的中心将两个 JButton 彼此相邻，赢了重新调整 JFrame 的大小时，不要重新调整按钮的大小。

I am trying to place two JButtons next to each other in the center of a JFrame, that won't re-size the buttons when the JFrame is re-sized.

要做到这一点，我放了两个具有 FlowLayout 的面板中的按钮，然后放置在具有中心 BorderLayout 的面板中。

To do this I placed the two buttons in a panel with a FlowLayout, that is then placed in a panel with a center BorderLayout.

但是，以下代码不会在 BorderLayout 的中心显示所选面板。

However the following code won't display the chosen panel in the center of the BorderLayout.

import java.awt.BorderLayout;
import java.awt.FlowLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class test extends JFrame {

    private JPanel panel1 = new JPanel();
    private JPanel panel2 = new JPanel();
    private JButton button1 = new JButton("one");
    private JButton button2 = new JButton("two");

    public test() {
        panel1.setLayout(new FlowLayout());
        panel1.add(button1);
        panel1.add(button2);

        panel2.setLayout(new BorderLayout());
        panel2.add(panel1, BorderLayout.CENTER);

        this.add(panel2);
    }

    public static void main(String[] args) {
        test frame = new test();
        frame.setVisible(true);
        frame.setSize(400, 400);
        frame.setLocationRelativeTo(null);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
}

推荐答案

设置 GridBagLayout 至 panel1 。

 panel1.setLayout(new GridBagLayout());

编辑：

@trashgod：I必须弄清楚默认约束是如何做到的。

@trashgod : I have to figure out how the default constraints do it.

因为字段 GridBagLayout.defaultConstraints ：

this field包含一个包含默认
值的gridbag约束实例，因此如果一个组件没有与它关联
的gridbag约束，那么该组件将被分配
defaultConstraints的副本。

This field holds a gridbag constraints instance containing the default values, so if a component does not have gridbag constraints associated with it, then the component will be assigned a copy of the defaultConstraints.

在正常情况下，必须创建 GridBagConstraints 对象并设置字段以指定每个对象上的约束。

In normal practice, one must have to create GridBagConstraints object and set fields to specify the constraints on each object.

引用教程：

在
组件上设置约束的首选方法是使用Container.add变体，传递
GridBagConstraints对象

The preferred approach to set constraints on a component is to use the Container.add variant, passing it a GridBagConstraints object

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