.pack() 有什么作用? [英] What does .pack() do?

问题描述

我正在学习 JPanel 和 GridLayout ，这段代码将生成一个带有 6 个按钮的简单 JPanel

I am learning about JPanel and GridLayout , this snippet of code will produce a simple JPanel with 6 buttons

package testing;


import java.io.*;
import java.util.*;
import java.security.*;
import javax.xml.bind.DatatypeConverter;
import java.lang.*;
import java.awt.*;
import javax.swing.*;

public class Testing 
{

    public static class GridPanel extends JPanel 
    {
        public GridPanel()
        {
            setLayout(new GridLayout(2,3));
            setBackground(Color.GREEN);
            this.setPreferredSize(new Dimension(500,500));

            JButton b1 = new JButton ("Button 1");
            JButton b2 = new JButton ("Button 2");
            JButton b3 = new JButton ("Button 3");
            JButton b4 = new JButton ("Button 4");
            JButton b5 = new JButton ("Button 5");
            JButton b6 = new JButton ("Button 6");

            add(b1);
            add(b2);
            add(b3);
            add(b4);
            add(b5);
            add(b6);
        }

    }



    public static void main(String[] args) 

    {
       GridPanel gp = new GridPanel();
       JFrame jf = new JFrame();
       jf.add(gp);
       jf.pack(); //code wouldnt work if i comment out this line
       jf.setVisible(true);

    }

}

我想知道如果我注释掉 jf.pack()

I am wondering why my code wouldnt work if i comment out jf.pack()

推荐答案

pack 方法调整框架的大小，使其所有内容都等于或大于其首选大小.pack 的另一种方法是通过调用 setSize 或 setBounds(也设置帧位置)来显式建立帧大小.一般来说，使用 pack 比调用 setSize 更可取，因为 pack 让框架布局管理器负责框架大小，而布局管理器擅长调整平台依赖性和其他影响组件大小的因素.

The pack method sizes the frame so that all its contents are at or above their preferred sizes. An alternative to pack is to establish a frame size explicitly by calling setSize or setBounds (which also sets the frame location). In general, using pack is preferable to calling setSize, since pack leaves the frame layout manager in charge of the frame size, and layout managers are good at adjusting to platform dependencies and other factors that affect component size.

来自 Java 教程

您还应该参考 Javadocs 任何时候您需要有关任何 Java API 的附加信息

You should also refer to Javadocs any time you need additional information on any Java API

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