下面的代码设置了这个问题.它有效,除了两个问题：
1.)绘制数据点,左上角为原点,y值向下下降
2.)屏幕上没有绘制y轴上的标记标记

任何人都可以告诉我如何修复下面的代码,以便它修复这两个问题,并做上面第一段描述的内容？

代码在以下两个java文件中：

DataGUI.java

import java.awt.*;
import java.util.ArrayList;
import javax.swing.*;

class DataGUI extends JFrame{
DataGUI() {
    super("X,Y Plot");
    this.setDefaultCloSEOperation(JFrame.EXIT_ON_CLOSE);
    this.setPreferredSize(new Dimension(800,400));
    this.pack();
    this.setSize(new Dimension(800,600));
    this.setLocationRelativeTo(null);


    setLayout(new GridLayout());
    ArrayList<Double> myDiffs = new ArrayList<Double>();
            myDiffs.add(25.0);
            myDiffs.add(9.0);
            myDiffs.add(7.0);
            myDiffs.add(16.0);
            myDiffs.add(15.0);
            myDiffs.add(6.0);
            myDiffs.add(2.0);
            myDiffs.add(8.0);
            myDiffs.add(2.0);
            myDiffs.add(27.0);
            myDiffs.add(14.0);
            myDiffs.add(12.0);
            myDiffs.add(19.0);
            myDiffs.add(10.0);
            myDiffs.add(11.0);
            myDiffs.add(8.0);
            myDiffs.add(19.0);
            myDiffs.add(2.0);
            myDiffs.add(16.0);
            myDiffs.add(5.0);
            myDiffs.add(18.0);
            myDiffs.add(23.0);
            myDiffs.add(9.0);
            myDiffs.add(4.0);
            myDiffs.add(8.0);
            myDiffs.add(9.0);
            myDiffs.add(3.0);
            myDiffs.add(3.0);
            myDiffs.add(9.0);
            myDiffs.add(13.0);
            myDiffs.add(17.0);
            myDiffs.add(7.0);
            myDiffs.add(0.0);
            myDiffs.add(2.0);
            myDiffs.add(3.0);
            myDiffs.add(33.0);
            myDiffs.add(23.0);
            myDiffs.add(26.0);
            myDiffs.add(12.0);
            myDiffs.add(12.0);
            myDiffs.add(19.0);
            myDiffs.add(14.0);
            myDiffs.add(9.0);
            myDiffs.add(26.0);
            myDiffs.add(24.0);
            myDiffs.add(13.0);
            myDiffs.add(19.0);
            myDiffs.add(2.0);
            myDiffs.add(7.0);
            myDiffs.add(28.0);
            myDiffs.add(15.0);
            myDiffs.add(2.0);
            myDiffs.add(5.0);
            myDiffs.add(17.0);
            myDiffs.add(2.0);
            myDiffs.add(16.0);
            myDiffs.add(19.0);
            myDiffs.add(2.0);
            myDiffs.add(31.0);
    DataPanel myPP = new DataPanel(myDiffs,this.getHeight(),this.getWidth());
    this.add(myPP);
    this.setVisible(true);// Display the panel.
}
public static void main(String[] args){
    DataGUI myDataGUI = new DataGUI();
    myDataGUI.setVisible(true);
}
}

DataPanel.java(注意：我编辑了下面的代码以包含trashgod的建议,但它仍然不起作用.)

import java.awt.*;
import java.awt.geom.AffineTransform;
import javax.swing.*;
import java.text.DecimalFormat;
import java.text.NumberFormat;
import java.util.*;

class DataPanel extends JPanel {
Insets ins; // holds the panel's insets
ArrayList<Double> myDiffs;
double maxDiff = Double.NEGATIVE_INFINITY;
double minDiff = Double.POSITIVE_INFINITY;
double maxPlot;

DataPanel(ArrayList<Double> Diffs,int h,int w){
    setOpaque(true);// Ensure that panel is opaque.
    setPreferredSize(new Dimension(w,h));
    setMinimumSize(new Dimension(w,h));
    setMaximumSize(new Dimension(w,h));
    myDiffs = Diffs;
    repaint();
    this.setVisible(true);
}

protected void paintComponent(Graphics g){// Override paintComponent() method.
    super.paintComponent(g);
    //get data about plotting environment and about text
    int height = getHeight();
    int width = getWidth();
    ins = getInsets();
    Graphics2D g2d = (Graphics2D)g;
    FontMetrics fontMetrics = g2d.getFontMetrics();
    String xString = ("x-axis label");
    int xStrWidth = fontMetrics.stringWidth(xString);
    int xStrHeight = fontMetrics.getHeight();
    String yString = "y-axis label";
    int yStrWidth = fontMetrics.stringWidth(yString);
    int yStrHeight = fontMetrics.getHeight();
    String titleString ="Title of Graphic";
    int titleStrWidth = fontMetrics.stringWidth(titleString);
    int titleStrHeight = fontMetrics.getHeight();
    int leftMargin = ins.left;
    //set parameters for inner rectangle
    int hPad=10;
    int vPad = 6;
    int testLeftStartPlotWindow = ins.left+5+(3*yStrHeight);
    int testInnerWidth = width-testLeftStartPlotWindow-ins.right-hPad;
    getMaxMinDiffs();
    getMaxPlotVal();
    double increment = 5.0;
    int numTicks = (int)(maxPlot/increment);//will use numTicks for: remainder,leftStartPlotWindow,innerRectangle+labels+tickmarks
    int remainder = testInnerWidth%numTicks;
    int leftStartPlotWindow = testLeftStartPlotWindow-remainder;
    System.out.println("remainder is: "+remainder);
    int bottomPad = (3*xStrHeight)-vPad;
    int blueTop = ins.bottom+(vPad/2)+titleStrHeight;
    int blueHeight = height-bottomPad-blueTop;
    int blueWidth = blueHeight;
    int blueBottom = blueHeight+blueTop;

    //plot outer rectangle
    g.setColor(Color.red);
    int redWidth = width-leftMargin-1;
    g.drawRect(leftMargin,ins.bottom,redWidth,height-ins.bottom-1);
    //write top label
    g.setColor(Color.black);
    g.drawString(titleString,leftStartPlotWindow+((blueWidth/2)-(titleStrWidth/2)),titleStrHeight);
    // fill,then plot,inner rectangle
    g.setColor(Color.white);
    g.fillRect(leftStartPlotWindow,blueTop,blueWidth,blueHeight);
    g.setColor(Color.blue);
    g.drawRect(leftStartPlotWindow,blueHeight);
    //scale the diffs to fit window
    double Scalar = blueWidth/maxPlot;
    ArrayList<Double> scaledDiffs = new ArrayList<Double>();
    for(int e = 0;e<myDiffs.size();e++){scaledDiffs.add(myDiffs.get(e)*Scalar);}
    //plot the scaled Diffs
    AffineTransform at = g2d.getTransform();//save the graphics context's transform
    g2d.translate(leftStartPlotWindow,blueTop);//translate origin to bottom-left corner of blue rectangle
    g2d.scale(1,-1);//invert the y-axis
    for(int w = 0;w<scaledDiffs.size();w++){
        if(w>0){
            double prior = scaledDiffs.get(w-1);
            int priorInt = (int)prior;
            double current = scaledDiffs.get(w);
            int currentInt = (int)current;
            g2d.drawOval(priorInt,currentInt,4,4);
        }
    }
    g2d.setTransform(at);//restore the transform for conventional rendering
    //write x-axis label
    g.setColor(Color.red);
    g.drawString(xString,leftStartPlotWindow+((blueWidth/2)-(xStrWidth/2)),height-ins.bottom-vPad);
    //write y-axis label
    g2d.rotate(Math.toRadians(-90),0);//rotate text 90 degrees counter-clockwise
    g.drawString(yString,-(height/2)-(yStrWidth/2),yStrHeight);
    g2d.rotate(Math.toRadians(+90),0);//rotate text 90 degrees clockwise
    // draw tick marks on x-axis
    NumberFormat formatter = new DecimalFormat("#0.0");
    double k = (double)blueWidth/(double)numTicks;
    double iteration = 0;
    for(int h=0;h<=numTicks;h++){
        int xval = (int)(h*k);
        g.setColor(Color.red);
        g.drawLine(leftStartPlotWindow+xval,blueBottom+2,leftStartPlotWindow+xval,blueBottom+(xStrHeight/2));//draw tick marks
        g.drawString(formatter.format(iteration),leftStartPlotWindow+xval-(fontMetrics.stringWidth(Double.toString(iteration))/2),blueBottom+(xStrHeight/2)+13);
        iteration+=increment;
    }
    // draw tick marks on y-axis
    iteration = 0;
    for(int h=0;h<=numTicks;h++){
        int yval = (int)(h*k);
        g.setColor(Color.red);
        g.drawLine(leftStartPlotWindow-2,blueBottom-yval,leftStartPlotWindow-(yStrHeight/2),blueBottom-yval);//draw tick marks
        g2d.rotate(Math.toRadians(-90),0);//rotate text 90 degrees counter-clockwise
        g.drawString(formatter.format(iteration),leftStartPlotWindow-2,blueBottom-(fontMetrics.stringWidth(Double.toString(iteration))/2));
        g2d.rotate(Math.toRadians(+90),0);//rotate text 90 degrees clockwise
        iteration+=increment;
    }
}
void getMaxMinDiffs(){// get max and min of Diffs
    for(int u = 0;u<myDiffs.size();u++){
        if(myDiffs.get(u)>maxDiff){maxDiff = myDiffs.get(u);}
        if(myDiffs.get(u)<minDiff){minDiff = myDiffs.get(u);}
    }
}
void getMaxPlotVal(){
    maxPlot = maxDiff;
    maxPlot += 1;//make sure maxPlot is bigger than the max data value
    while(maxPlot%5!=0){maxPlot+=1;}//make sure maxPlot is a multiple of 5
}
}

此外,与往常一样,非常感谢关于该主题的文章或教程的链接.