Java 将图形（g）绘制到jpanel中

我试图在下面的java小程序中绘制一些带有随机整数的条形图，但是覆盖有一个错误我是java新手我试图在代码中绘制两个区域draw方法在最底部另一个是第二个面板区域 我的目标是什么

尺寸x，y不是坐标

-总尺寸=200250

-位置gui=200,50

-图像=140150

-precip=100,20

-温度=20100

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.Font;
import java.awt.GridBagLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import javax.swing.*;
import java.util.*;

public class Final2 extends JFrame
{
    //Panels
    JPanel locationGui = new JPanel ();
    JPanel temp = new JPanel ();
    JPanel percip = new JPanel ();
    JPanel image = new JPanel ();
    //Location gui components
    JButton Enter, Exit;
    JTextField location;
    JLabel city;
    JRadioButton time;
    JComboBox Seasons;
    //bar # genertor
    Random rand = new Random ();
    int P = rand.nextInt (100) + 1; //Random Precipitation
    int H = rand.nextInt (50) + 1; //Random Heat
    public Final2 ()
    {
        init ();

    }


    public void init ()
    {
        Font font = new Font ("impact", Font.PLAIN, 20);
        //________________________________________________new panel____________________
        locationGui.setBackground (Color.RED);
        JLabel guiLabel = new JLabel ("");
        guiLabel.setFont (font);

        Enter = new JButton ("Enter");
        Exit = new JButton ("exit");



        city = new JLabel ("What city?");
        location = new JTextField (20); //location entry field


        Seasons = new JComboBox ();
        Seasons.addItem ("Summer");
        Seasons.addItem ("Fall");
        Seasons.addItem ("Winter");
        Seasons.addItem ("Spring");


        time = new JRadioButton ("check if night?");


        locationGui.add (city);
        locationGui.add (location);
        locationGui.add (Seasons);
        locationGui.add (time);



        locationGui.add (guiLabel);


        //________________________________________________new panel____________________
        temp.setBackground (Color.BLUE);
        temp.setLayout (new GridBagLayout ());
        JLabel tempLabel = new JLabel ("Temp");
        tempLabel.setFont (font);
        temp.add (tempLabel);

        //________________________________________________new panel____________________
        percip.setBackground (Color.GREEN);
        JLabel pLabel = new DrawingPanel (); //where it should be

        percip.add (pLabel);

        //________________________________________________new panel____________________
        image.setBackground (Color.ORANGE);
        image.setLayout (new GridBagLayout ());
        JLabel imageLabel = new JLabel ("Image");
        imageLabel.setFont (font);
        image.add (imageLabel);

        Container contentPane = getContentPane ();

        contentPane.setLayout (new BorderLayout ());
        contentPane.add (locationGui, BorderLayout.NORTH);
        contentPane.add (temp, BorderLayout.EAST);
        contentPane.add (percip, BorderLayout.SOUTH);
        contentPane.add (image, BorderLayout.CENTER);

        setContentPane (contentPane);
        setDefaultCloseOperation (EXIT_ON_CLOSE);
        setSize (400, 400);
        setLocationRelativeTo (null);
        setVisible (true);
    }


    public static void main (String[] args)
    {
        SwingUtilities.invokeLater (new Runnable ()

        {


            public void run ()
            {
                new Final2 ();
            }
        }


        );
    }


    private class DrawingPanel extends javax.swing.JPanel {//area i have issues with atm
    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2d = (Graphics2D) g;
        drawPercip(g);
    }
    @Override 
    public Dimension getPreferredSize() {
        return new Dimension(200, 400);
    }



    }


    public void drawPercip (Graphics g)
    {
        //Precipitation Bar
        g.setColor (Color.black);
        g.drawRect (40, 170, 100, 20); //outline of bar
        g.setColor (Color.blue);
        g.fillRect (40 + 1, 170 + 4, P, 14); //indicator bar (+4 puts space beetween outline bar)
    }


    public void drawTemp (Graphics g)
    {
        //Temparature Bar
        g.setColor (Color.red);
        g.fillRect (170 + 4, 50, 14, 100); //Covers in
        g.setColor (Color.black);
        g.drawRect (170, 50, 20, 100); //outline of bar
        g.setColor (Color.white);
        g.fillRect (170 + 4, 50 + 1, 16, 100 - H); //indicator bar (+4 puts space beetween outline bar)
    }




}

我当前的错误（4）发生在@override的这段代码中。提供的唯一消息是“非法令牌”和“意外符号被忽略”idk为什么它不提供更多信息

 private class DrawingPanel extends javax.swing.JPanel {//area i have issues with atm
    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2d = (Graphics2D) g;
        drawPercip(g);
    }
    @Override 
    public Dimension getPreferredSize() {
        return new Dimension(200, 400);
    }

---

首先我没有看到小程序

其次，

DrawingPanel

不是

JLabel

JLabel pLabel = new DrawingPanel(); //where it should be

将

pLable

类型更改为

JComponent

或

JPanel

或

DrawingPanel

，具体取决于您希望从每个类中访问的内容

第三，你不应该依赖神奇的数字

public void drawPercip(Graphics g) {
    //Precipitation Bar
    g.setColor(Color.black);
    g.drawRect(40, 170, 100, 20); //outline of bar
    g.setColor(Color.blue);
    g.fillRect(40 + 1, 170 + 4, P, 14); //indicator bar (+4 puts space beetween outline bar)
}

public void drawTemp(Graphics g) {
    //Temparature Bar
    g.setColor(Color.red);
    g.fillRect(170 + 4, 50, 14, 100); //Covers in
    g.setColor(Color.black);
    g.drawRect(170, 50, 20, 100); //outline of bar
    g.setColor(Color.white);
    g.fillRect(170 + 4, 50 + 1, 16, 100 - H); //indicator bar (+4 puts space beetween outline bar)
}

无法保证面板的高度和宽度与您认为的相同。使用

getWidth

和

getHeight

方法

第四，如果你想拥有更多的

绘图面板

，你应该

int P = rand.nextInt(100) + 1; //Random Precipitation
int H = rand.nextInt(50) + 1; //Random Heat

绘图面板的一部分

---

你也应该抽出时间通读

如果你有错误，你应该把它们贴出来。请注意，

paintComponent

应该受到保护，但这不应该带来问题。我是一个业余爱好者，所以我知道受保护的意思，错误是“非法令牌”和“忽略意外符号”。我使用Ready java作为编译器1）不要解释错误消息。而是将整个消息作为问题的编辑发布。在代码中指出错误发生的位置。这不是解释，而是@override上的legitamate消息在@override上显示非法标记，rest on override“Ready”Java编译器支持哪一级别的API支持。它可能不支持注释…我不太明白你在说什么，但我添加了更多的信息，围绕着最终的布局理念和每个项目我想要的尺寸，你不明白什么部分？1）你说要将plabel更改为DrawingPanel，它已经是2）我从未听说过“神奇数字”@CurtisSpence 1。否，

pLabel

已定义，明确为

JLabel

，

JLabel pLabel=new DrawingPanel（）//如果它应该是

，

JLabel

和

DrawingPanel

是两种不同类型的对象，它们不能相互分配。2.您无法保证

绘图面板的大小。布局管理器可能需要为布局中的其他组件提供更多或更少的空间，从而更改
绘图面板的大小，这意味着当绘制时，它将无法正确绘制。因此JLabel pLabel=new DrawingPanel（）；是否实际为DrawingPanel plabel=新DrawingPanel（）；