java - 仅重新绘制 JFrame 内的特定 JPanel

Question

我正在尝试为 panel_1 JPanel 创建一个绘制组件，但我不知道该怎么做。这是我的课。

此代码可以工作，但它不会绘制 panel_1。如果我尝试将其添加到面板而不进行绘制，则效果很好。我还需要该面板以给定的时间间隔自动刷新(重新绘制)。请帮助我。 :D

import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.Timer;
import javax.swing.border.EmptyBorder;

public class GUI extends JFrame implements ActionListener {

    private JPanel contentPane;
    private JTextField textField;
    private JTextField textField_1;
    private JTextField textField_2;
    private JTextField textField_3;
    private JButton btnStop, btnStart;
    private JComboBox comboBox_1, comboBox;
    private Manager manager = new Manager();
    private String arrMin, arrMax, svcMin, svcMax, simTime;
    private JTextField textField_4;
    private JPanel panel_1 = new JPanel(){
        @Override
        public void paintComponent(Graphics g){

        paintComponents(g);
         panel_1.setBackground(Color.orange);
         panel_1.setVisible(true);

          System.out.println("Just testing");
        }
    };

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    GUI frame = new GUI();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the frame.
     */
    public GUI() {
        setResizable(false);
        setForeground(Color.DARK_GRAY);
        setBackground(Color.DARK_GRAY);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 700, 500);
        contentPane = new JPanel();
        contentPane.setForeground(Color.DARK_GRAY);
        contentPane.setBackground(Color.DARK_GRAY);
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        setContentPane(contentPane);
        contentPane.setLayout(null);

        JPanel panel = new JPanel();
        panel.setBounds(12, 12, 434, 346);
        panel.setForeground(Color.LIGHT_GRAY);
        contentPane.add(panel);
        panel.setLayout(null);

        JLabel lblArrivingTime = new JLabel("Arriving time");
        lblArrivingTime.setBounds(12, 367, 94, 15);
        lblArrivingTime.setForeground(Color.LIGHT_GRAY);
        contentPane.add(lblArrivingTime);

        JLabel lblMin = new JLabel("Min");
        lblMin.setBounds(12, 395, 70, 15);
        lblMin.setForeground(Color.LIGHT_GRAY);
        contentPane.add(lblMin);

        JLabel lblMax = new JLabel("Max");
        lblMax.setBounds(12, 418, 70, 15);
        lblMax.setForeground(Color.LIGHT_GRAY);
        contentPane.add(lblMax);

        textField = new JTextField();
        textField.setBounds(58, 394, 48, 16);
        contentPane.add(textField);
        textField.setColumns(10);

        textField_1 = new JTextField();
        textField_1.setBounds(58, 422, 48, 15);
        contentPane.add(textField_1);
        textField_1.setColumns(10);

        JLabel lblServiceTime = new JLabel("Service Time");
        lblServiceTime.setBounds(152, 367, 105, 15);
        lblServiceTime.setForeground(Color.LIGHT_GRAY);
        contentPane.add(lblServiceTime);

        JLabel lblMin_1 = new JLabel("Min");
        lblMin_1.setBounds(152, 395, 51, 15);
        lblMin_1.setForeground(Color.LIGHT_GRAY);
        contentPane.add(lblMin_1);

        JLabel lblMax_1 = new JLabel("Max");
        lblMax_1.setBounds(152, 418, 70, 15);
        lblMax_1.setForeground(Color.LIGHT_GRAY);
        contentPane.add(lblMax_1);

        textField_2 = new JTextField();
        textField_2.setBounds(209, 393, 48, 17);
        contentPane.add(textField_2);
        textField_2.setColumns(10);

        textField_3 = new JTextField();
        textField_3.setBounds(209, 417, 48, 17);
        contentPane.add(textField_3);
        textField_3.setColumns(10);

        JLabel lblSimSetup = new JLabel("Sim. Setup");
        lblSimSetup.setBounds(292, 367, 94, 15);
        lblSimSetup.setForeground(Color.LIGHT_GRAY);
        contentPane.add(lblSimSetup);

        JLabel lblQueue = new JLabel("Queue");
        lblQueue.setBounds(292, 395, 70, 15);
        lblQueue.setForeground(Color.LIGHT_GRAY);
        contentPane.add(lblQueue);

        String[] numbers = { "1", "2", "3", "4" };
        comboBox = new JComboBox(numbers);
        comboBox.setBounds(345, 395, 75, 15);
        contentPane.add(comboBox);

        JLabel lblMode = new JLabel("Mode");
        lblMode.setBounds(292, 418, 70, 15);
        lblMode.setForeground(Color.LIGHT_GRAY);
        contentPane.add(lblMode);

        String[] mode = { "Time", "Number" };
        comboBox_1 = new JComboBox(mode);
        comboBox_1.setBounds(345, 413, 75, 15);
        contentPane.add(comboBox_1);

        JLabel lblActions = new JLabel("Actions");
        lblActions.setBounds(484, 367, 70, 15);
        lblActions.setForeground(Color.LIGHT_GRAY);
        contentPane.add(lblActions);

        btnStart = new JButton("Start");
        btnStart.setBounds(482, 392, 81, 20);
        contentPane.add(btnStart);

        btnStop = new JButton("Stop");
        btnStop.setBounds(482, 415, 81, 20);
        contentPane.add(btnStop);

        JLabel lblTime = new JLabel("Time");
        lblTime.setBounds(292, 440, 70, 15);
        lblTime.setForeground(Color.LIGHT_GRAY);
        contentPane.add(lblTime);

        textField_4 = new JTextField();
        textField_4.setBounds(345, 438, 75, 17);
        contentPane.add(textField_4);
        textField_4.setColumns(10);



        panel_1.setBounds(484, 12, 202, 346);
        contentPane.add(panel_1);
        panel_1.setLayout(null);

        JTextArea textArea = new JTextArea();
        textArea.setBounds(158, 12, -126, 322);
        panel_1.add(textArea);

        btnStop.addActionListener(this);
        btnStart.addActionListener(this);
        comboBox.addActionListener(this);
        comboBox_1.addActionListener(this);


    }

    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == btnStop) {
            this.dispose();
            System.exit(NORMAL);
        } else if (e.getSource() == btnStart) {
            String nrQueues = (String) comboBox.getSelectedItem();
            arrMin = textField.getText();
            arrMax = textField_1.getText();
            svcMin = textField_2.getText();
            svcMax = textField_3.getText();
            simTime = textField_4.getText();
            int aMin = 0;
            int aMax = 0;
            int sMin = 0;
            int sMax = 0;
            int sTime = 0;
            int nQueues = 1;
            try {
                nQueues = Integer.parseInt(nrQueues);
                aMin = Integer.parseInt(arrMin);
                aMax = Integer.parseInt(arrMax);
                sMin = Integer.parseInt(svcMin);
                sMax = Integer.parseInt(svcMax);
                sTime = Integer.parseInt(simTime);
            } catch (NumberFormatException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }

            String s = (String) comboBox_1.getSelectedItem();
            System.out.println("Selected: " + s);
            boolean mode = true;
            if (s.equals("Time")) {
                mode = true;
            } else {
                mode = false;
            }
            manager.startSimulation(aMin * 1000, aMax * 1000, sMin * 1000,
                    sMax * 1000, sTime * 1000, nQueues, mode);

        }
    }

}

当然，处理程序与本例无关，因为我只对绘制该面板感兴趣。

Answer 1

首先，这个...

private JPanel panel_1 = new JPanel(){
    @Override
    public void paintComponent(Graphics g){
        paintComponents(g);
        panel_1.setBackground(Color.orange);
        panel_1.setVisible(true);

        System.out.println("Just testing");
    }
};

这不是定制绘画的用途。您永远不应该从任何绘制方法内部更改组件或任何组件的状态。

这可能会触发一个新的重画请求，这将使您陷入永无休止的绘画循环......

调用paintComponents(g);将产生StackOverflowException。您不应该以任何方式调用 paintComponents (请注意末尾的 s)，但您应该调用 super.paintComponent(g);

JPanel 默认情况下可见。

就目前情况而言，您根本不需要做任何您想做的事情...

不要使用null布局。 Swing 被设计为与布局管理器一起使用，如果没有它们，您将遇到无穷无尽的屏幕更新问题，此外，像素完美布局在现代用户界面设计中是一种幻觉，您无法控制字体、渲染管道或其他目标系统的各个方面可能会影响文本等元素的渲染大小。

看看Laying Out Components Within a Container了解更多详情