如何在不同的位置绘制多个JLabel？（图标不显示）

Question

我正在尝试使用for loop在许多不同的位置绘制多个图标。出于某种原因，他们就是不出现。我不知道我遗漏了什么——我找到的唯一线索是关于将layout设置为null，但IntelliJ会覆盖它。图标应该显示在“mapa”面板中。我尝试手动添加它们，但没有任何改变。

我的代码：

package okna;

import logistyka.Walker;
import logistyka.errand.Errand;

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;

public class WalkerGUI extends JFrame{
    private JPanel mainPanel;
    private JLabel walkerName;
    private  JTextField walkerNameField;
    private JLabel walkerAddress;
    private  JTextField walkerAddressField;
    private JButton searchErrandsButton;
    private JComboBox errandsComboBox;
    private JLabel errandsList;
    private JTextField walletValue;
    private JLabel Wallet;
    private JRadioButton archivalErrandsRadioButton;
    private JRadioButton currentErrandsRadioButton;
    private JButton payOutButton;
    private JButton seeProfileButton;
    private JPanel mapa;
    ArrayList<Errand> masterErrandList = new ArrayList<>();

    public WalkerGUI(Walker w, ArrayList<Errand> masterErrandList)  {
        setContentPane(mainPanel);
        ArrayList<JLabel> errandsLabels = new ArrayList<>();
        ImageIcon x = new ImageIcon(System.getProperty("user.dir") + "\\src\\x.png");
        this.masterErrandList = masterErrandList;
        for (Errand errand: masterErrandList) {
            JLabel label = new JLabel("whtvr");
            label.setIcon(x);
            label.setLocation((int)errand.getAddress().getX(),(int)errand.getAddress().getY());
            label.setMinimumSize(new Dimension(20,20));
            label.setPreferredSize(new Dimension(20,20));
            label.setVisible(true);
            errandsLabels.add(label);
        }

        walkerNameField.setText(w.getDescription().getName());
        walkerAddressField.setText(w.getDescription().getHomeRegion().getCurrentAddress().toString());
        walletValue.setText(String.valueOf(w.getWalletSatus()));
        seeProfileButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                JFrame frame = new ProfileGUI(w);
                frame.pack();
                frame.setVisible(true);
            }
        });
        payOutButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                w.setWalletSatus(0);
                walletValue.setText(String.valueOf(w.getWalletSatus()));
            }
        });
    }


}

Answer 1

您可以使用SpringLayout（而不是null布局）。方法Errand.get地址（）. getX（）将返回JLabel左边缘与其容器左边缘的距离，而Errand.get地址（）. getY（）将返回JLabel顶部边缘与其容器顶部边缘的距离。

你问题中的代码不是一个最小的、可复制的例子，所以下面的代码应该被视为概念的证明。

import java.awt.EventQueue;
import java.awt.Point;

import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SpringLayout;

public class SprinGui {

    private void createAndDisplayGui() {
        JFrame frame = new JFrame("Spring");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JPanel contentPane = (JPanel) frame.getContentPane();
        SpringLayout layout = new SpringLayout();
        contentPane.setLayout(layout);
        Point[] points = new Point[]{new Point(5, 5),
                                     new Point(5, 100),
                                     new Point(225, 150),
                                     new Point(250, 210)};
        Class<?> meClass = getClass();
        Icon[] icons = new Icon[4];
        icons[0] = new ImageIcon(meClass.getResource("coffee.png"));
        icons[1] = new ImageIcon(meClass.getResource("dollar.png"));
        icons[2] = new ImageIcon(meClass.getResource("dynamite.png"));
        icons[3] = new ImageIcon(meClass.getResource("soccer-player.png"));
        for (int i = 0; i < 4; i++) {
            JLabel label = new JLabel(icons[i]);
            contentPane.add(label);
            layout.putConstraint(SpringLayout.WEST,
                                 label,
                                 points[i].x,
                                 SpringLayout.WEST,
                                 contentPane);
            layout.putConstraint(SpringLayout.NORTH,
                                 label,
                                 points[i].y,
                                 SpringLayout.NORTH,
                                 contentPane);
        }
        frame.setSize(450, 300);
        frame.setLocationByPlatform(true);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SprinGui instance = new SprinGui();
        EventQueue.invokeLater(() -> instance.createAndDisplayGui());
    }
}

这就是GUI的外观。

请注意，如何使用图标可能也很有帮助。