java - 使用 GridBagLayout JComponent 未在 JPanel 上显示

Question

因此，经过一番研究后，我倾向于需要事先指定 JComponent 的首选大小，因为 JComponent 确实没有首选大小本质上。

向我的 JComponent 添加首选尺寸是否可以解决面板上显示的问题？

如果这是解决问题的方法，那么最好的方法是什么？我读过不同的人说使用 setPreferedSize 和其他人说你根本不应该使用此方法。

import java.util.Scanner;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
import java.awt.event.*;
import java.awt.GridBagLayout;
import java.awt.GridBagConstraints;
import javax.swing.JLabel;
import java.awt.Insets;
import javax.swing.JTextField;
import javax.swing.JButton;
import java.awt.Container;
import java.awt.ComponentOrientation;

public class ArrayViewer 
{
    static int[] array;
    static int[] sortedArray;

    public static void main(String[] args)
    {
        int size=0;
        Scanner in=new Scanner(System.in);
        //ask for the size of the array until the user enters a size in the right range
        do
        {
            System.out.print("Enter the size of the array (should be between 10 and 100): ");
            size=in.nextInt();
        }
        while (size<10 || size>100);

        JFrame frame = new JFrame();
        frame.setSize(1000,1000);
        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        array= ArrayUtil.randomIntArray(size,200);//create a random array of given size and entries ranging from 0 to 100
        System.out.println(ArrayUtil.printArray(array));



        //Set up the content pane.
        addComponentsToPane(frame.getContentPane());

        //Display the window.
        frame.pack();
        frame.setVisible(true);


    }

    public static void addComponentsToPane(Container pane) 
    {
        pane.setComponentOrientation(ComponentOrientation.LEFT_TO_RIGHT);
        pane.setLayout(new GridBagLayout());
        GridBagConstraints c = new GridBagConstraints();

        //For each component to be added to this container:

        ArrayComponent arrayGraph = new ArrayComponent(array, false);
        //...Set instance variables in the GridBagConstraints instance...
        c.ipady = 0;       //reset to default
        c.weighty = 0.0;   //request any extra vertical space
        c.anchor = GridBagConstraints.PAGE_END; //bottom of space
        c.insets = new Insets(0,0,0,0);  //no padding
        c.gridx = 0;       //begins in 1st cell of..
        c.gridwidth = 2;   //2 columns wide
        c.gridy = 1;       //2nd row
        pane.add(arrayGraph, c);


}

ArrayComponent类

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.util.ArrayList;
import javax.swing.JComponent;

public class ArrayComponent extends JComponent
{
    // instance variables - replace the example below with your own
    int[] theArray;
    int highlightIndex;
    boolean sorted;

    /**
     * Constructor for objects of class ArrayComponent
     */
    public ArrayComponent(int[] input, boolean sorted)
    {
        // initialise instance variables
        theArray = input;
        this.sorted = sorted;
    }

    public void paintComponent(Graphics g)
    {
        if (sorted == false)
        {
            Graphics2D g2 = (Graphics2D)g;
            int x = 25;
            int size = theArray.length;
            for(int i = 0; i<size; i++)
            {

                g2.drawRect(x,15,5,theArray[i]);
                x = x+10;    
            }

        }

    }
}

ArrayUtil 类

public class ArrayUtil
{
    private static Random generator = new Random();

    /**
    Creates an array filled with random values.
    @param length the length of the array
    @param n the number of possible random values
    @return an array filled with length numbers between
    0 and n - 1
     */
    public static int[] randomIntArray(int length, int n)
    {  
        int[] a = new int[length];      
        for (int i = 0; i < a.length; i++)
            a[i] = generator.nextInt(n);

        return a;
    }

    public static String printArray(int[] array)
    {
        String str=("array=[");
        int k=0;
        for (k=0;k<array.length-1;k++)
            str=str+array[k]+", ";              
        str=str+array[k]+"]";
        return str;
    }

Answer 1

重写getPreferredSize而不是使用setPreferredSize

您还可以使用 GridBagLayout 通过指定 fill 属性并更改 weightx/y 来影响大小属性(property)