用Java绘制一个简单的直线图

In my program I want to draw a simple score line graph. I have a text file and on each line is an integer score, which I read in and want to pass as argument to my graph class. I'm having some trouble implementing the graph class and all the examples I've seen have their methods in the same class as their main, which I won't have.

在我的程序中，我想画一个简单的分数线图。我有一个文本文件，在每一行上都有一个整数值，我读取它并将其作为参数传递给我的graph类。我在实现图形类时遇到了一些麻烦，我看到的所有示例都将它们的方法与它们的main函数放在同一个类中，而这是我所没有的。

I want to be able to pass my array to the object and generate a graph, but when calling my paint method it is asking me for a Graphics g... This is what I have so far:

我希望能够将数组传递给对象并生成一个图形，但是当调用paint方法时，它会向我要一个图形g……这是我目前所拥有的:

public class Graph extends JPanel {

    public void paintGraph (Graphics g){

        ArrayList<Integer> scores = new ArrayList<Integer>(10);

        Random r = new Random();

        for (int i : scores){
            i = r.nextInt(20);
            System.out.println(r);
        }

        int y1;
        int y2;

        for (int i = 0; i < scores.size(); i++){
            y1 = scores.get(i);
            y2 = scores.get(i+1);
            g.drawLine(i, y1, i+1, y2);
        }
    }
}

For now I have inserted a simple random number generator to fill up my array.

现在我插入了一个简单的随机数生成器来填充数组。

I have an existing frame and basically want to instantiate the Graph class and mount the panel onto my frame. I'm really sorry that this question seems so jumbled by the way, but I've had little sleep...

我有一个现有的框架，基本上想要实例化Graph类并将面板挂载到我的框架上。我真的很抱歉这个问题看起来如此混乱，但是我几乎没有睡过觉……

The code in my main statement is:

我的主要声明中的代码是:

testFrame = new JFrame();
testFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Graph graph = new Graph();
testFrame.add(graph);

I'm not sure exactly what an SSCE is but this is my attempt at one:

我不确定SSCE到底是什么，但这是我的一个尝试:

public class Test {

    JFrame testFrame;
    public Test() {
        testFrame = new JFrame();
        testFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        Graph graph = new Graph();
        testFrame.add(graph);
        testFrame.setBounds(100, 100, 764, 470);
        testFrame.setVisible(true);
    }

Graph.java

Graph.java

public class Graph extends JPanel {
    public Graph() {
       setSize(500, 500);
    }

    @Override
    public void paintComponent(Graphics g) {
        Graphics2D gr = (Graphics2D) g; // This is if you want to use Graphics2D
        // Now do the drawing here
        ArrayList<Integer> scores = new ArrayList<Integer>(10);

        Random r = new Random();

        for (int i : scores) {
            i = r.nextInt(20);
            System.out.println(r);
        }

        int y1;
        int y2;

        for (int i = 0; i < scores.size() - 1; i++) {
            y1 = (scores.get(i)) * 10;
            y2 = (scores.get(i + 1)) * 10;
            gr.drawLine(i * 10, y1, (i + 1) * 10, y2);
        }
    }
}

6 个解决方案

#1

Problems with your code and suggestions:

您的代码和建议有问题:

• Again you need to change the preferredSize of the component (here the Graph JPanel), not the size
• 同样，您需要更改组件的首选项(这里是图形JPanel)，而不是大小。
• Don't set the JFrame's bounds.
• 不要设置JFrame的界限。
• Call pack() on your JFrame after adding components to it and before calling setVisible(true)
• 在向JFrame添加组件之后，在调用setVisible(true)之前调用pack()
• Your foreach loop won't work since the size of your ArrayList is 0 (test it to see that this is correct). Instead use a for loop going from 0 to 10.
• 由于ArrayList的大小为0，所以foreach循环不起作用(测试它以确保它是正确的)。相反，使用从0到10的for循环。
• You should not have program logic inside of your paintComponent(...) method but only painting code. So I would make the ArrayList a class variable and fill it inside of the class's constructor.
• 您不应该在paintComponent(…)方法中包含程序逻辑，而应该只绘制代码。因此，我将使ArrayList成为类变量，并将其填充到类的构造函数中。

For example:

例如:

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.RenderingHints;
import java.awt.Stroke;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import javax.swing.*;

@SuppressWarnings("serial")
public class DrawGraph extends JPanel {
   private static final int MAX_SCORE = 20;
   private static final int PREF_W = 800;
   private static final int PREF_H = 650;
   private static final int BORDER_GAP = 30;
   private static final Color GRAPH_COLOR = Color.green;
   private static final Color GRAPH_POINT_COLOR = new Color(150, 50, 50, 180);
   private static final Stroke GRAPH_STROKE = new BasicStroke(3f);
   private static final int GRAPH_POINT_WIDTH = 12;
   private static final int Y_HATCH_CNT = 10;
   private List<Integer> scores;

   public DrawGraph(List<Integer> scores) {
      this.scores = scores;
   }

   @Override
   protected void paintComponent(Graphics g) {
      super.paintComponent(g);
      Graphics2D g2 = (Graphics2D)g;
      g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

      double xScale = ((double) getWidth() - 2 * BORDER_GAP) / (scores.size() - 1);
      double yScale = ((double) getHeight() - 2 * BORDER_GAP) / (MAX_SCORE - 1);

      List<Point> graphPoints = new ArrayList<Point>();
      for (int i = 0; i < scores.size(); i++) {
         int x1 = (int) (i * xScale + BORDER_GAP);
         int y1 = (int) ((MAX_SCORE - scores.get(i)) * yScale + BORDER_GAP);
         graphPoints.add(new Point(x1, y1));
      }

      // create x and y axes 
      g2.drawLine(BORDER_GAP, getHeight() - BORDER_GAP, BORDER_GAP, BORDER_GAP);
      g2.drawLine(BORDER_GAP, getHeight() - BORDER_GAP, getWidth() - BORDER_GAP, getHeight() - BORDER_GAP);

      // create hatch marks for y axis. 
      for (int i = 0; i < Y_HATCH_CNT; i++) {
         int x0 = BORDER_GAP;
         int x1 = GRAPH_POINT_WIDTH + BORDER_GAP;
         int y0 = getHeight() - (((i + 1) * (getHeight() - BORDER_GAP * 2)) / Y_HATCH_CNT + BORDER_GAP);
         int y1 = y0;
         g2.drawLine(x0, y0, x1, y1);
      }

      // and for x axis
      for (int i = 0; i < scores.size() - 1; i++) {
         int x0 = (i + 1) * (getWidth() - BORDER_GAP * 2) / (scores.size() - 1) + BORDER_GAP;
         int x1 = x0;
         int y0 = getHeight() - BORDER_GAP;
         int y1 = y0 - GRAPH_POINT_WIDTH;
         g2.drawLine(x0, y0, x1, y1);
      }

      Stroke oldStroke = g2.getStroke();
      g2.setColor(GRAPH_COLOR);
      g2.setStroke(GRAPH_STROKE);
      for (int i = 0; i < graphPoints.size() - 1; i++) {
         int x1 = graphPoints.get(i).x;
         int y1 = graphPoints.get(i).y;
         int x2 = graphPoints.get(i + 1).x;
         int y2 = graphPoints.get(i + 1).y;
         g2.drawLine(x1, y1, x2, y2);         
      }

      g2.setStroke(oldStroke);      
      g2.setColor(GRAPH_POINT_COLOR);
      for (int i = 0; i < graphPoints.size(); i++) {
         int x = graphPoints.get(i).x - GRAPH_POINT_WIDTH / 2;
         int y = graphPoints.get(i).y - GRAPH_POINT_WIDTH / 2;;
         int ovalW = GRAPH_POINT_WIDTH;
         int ovalH = GRAPH_POINT_WIDTH;
         g2.fillOval(x, y, ovalW, ovalH);
      }
   }

   @Override
   public Dimension getPreferredSize() {
      return new Dimension(PREF_W, PREF_H);
   }

   private static void createAndShowGui() {
      List<Integer> scores = new ArrayList<Integer>();
      Random random = new Random();
      int maxDataPoints = 16;
      int maxScore = 20;
      for (int i = 0; i < maxDataPoints ; i++) {
         scores.add(random.nextInt(maxScore));
      }
      DrawGraph mainPanel = new DrawGraph(scores);

      JFrame frame = new JFrame("DrawGraph");
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.getContentPane().add(mainPanel);
      frame.pack();
      frame.setLocationByPlatform(true);
      frame.setVisible(true);
   }

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

Which will create a graph that looks like so:

它会创建一个这样的图形:

#2

Just complementing Hovercraft Full Of Eels's solution:

补充气垫船充满了鳗鱼的解决方案:

I reworked his code, tweaked it a bit, adding a grid, axis labels and now the Y-axis goes from the minimum value present up to the maximum value. I planned on adding a couple of getters/setters but I didn't need them, you can add them if you want.

我修改了他的代码，稍微修改了一下，添加了一个网格，轴标签现在y轴从最小值到最大值。我计划添加一些getter /setter，但是我不需要它们，如果你想添加的话可以添加它们。

Here is the Gist link, I'll also paste the code below: GraphPanel on Gist

这是要点链接，我也将粘贴下面的代码:在要点上的图形面板

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.RenderingHints;
import java.awt.Stroke;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class GraphPanel extends JPanel {

    private int width = 800;
    private int heigth = 400;
    private int padding = 25;
    private int labelPadding = 25;
    private Color lineColor = new Color(44, 102, 230, 180);
    private Color pointColor = new Color(100, 100, 100, 180);
    private Color gridColor = new Color(200, 200, 200, 200);
    private static final Stroke GRAPH_STROKE = new BasicStroke(2f);
    private int pointWidth = 4;
    private int numberYDivisions = 10;
    private List<Double> scores;

    public GraphPanel(List<Double> scores) {
        this.scores = scores;
    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D) g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

        double xScale = ((double) getWidth() - (2 * padding) - labelPadding) / (scores.size() - 1);
        double yScale = ((double) getHeight() - 2 * padding - labelPadding) / (getMaxScore() - getMinScore());

        List<Point> graphPoints = new ArrayList<>();
        for (int i = 0; i < scores.size(); i++) {
            int x1 = (int) (i * xScale + padding + labelPadding);
            int y1 = (int) ((getMaxScore() - scores.get(i)) * yScale + padding);
            graphPoints.add(new Point(x1, y1));
        }

        // draw white background
        g2.setColor(Color.WHITE);
        g2.fillRect(padding + labelPadding, padding, getWidth() - (2 * padding) - labelPadding, getHeight() - 2 * padding - labelPadding);
        g2.setColor(Color.BLACK);

        // create hatch marks and grid lines for y axis.
        for (int i = 0; i < numberYDivisions + 1; i++) {
            int x0 = padding + labelPadding;
            int x1 = pointWidth + padding + labelPadding;
            int y0 = getHeight() - ((i * (getHeight() - padding * 2 - labelPadding)) / numberYDivisions + padding + labelPadding);
            int y1 = y0;
            if (scores.size() > 0) {
                g2.setColor(gridColor);
                g2.drawLine(padding + labelPadding + 1 + pointWidth, y0, getWidth() - padding, y1);
                g2.setColor(Color.BLACK);
                String yLabel = ((int) ((getMinScore() + (getMaxScore() - getMinScore()) * ((i * 1.0) / numberYDivisions)) * 100)) / 100.0 + "";
                FontMetrics metrics = g2.getFontMetrics();
                int labelWidth = metrics.stringWidth(yLabel);
                g2.drawString(yLabel, x0 - labelWidth - 5, y0 + (metrics.getHeight() / 2) - 3);
            }
            g2.drawLine(x0, y0, x1, y1);
        }

        // and for x axis
        for (int i = 0; i < scores.size(); i++) {
            if (scores.size() > 1) {
                int x0 = i * (getWidth() - padding * 2 - labelPadding) / (scores.size() - 1) + padding + labelPadding;
                int x1 = x0;
                int y0 = getHeight() - padding - labelPadding;
                int y1 = y0 - pointWidth;
                if ((i % ((int) ((scores.size() / 20.0)) + 1)) == 0) {
                    g2.setColor(gridColor);
                    g2.drawLine(x0, getHeight() - padding - labelPadding - 1 - pointWidth, x1, padding);
                    g2.setColor(Color.BLACK);
                    String xLabel = i + "";
                    FontMetrics metrics = g2.getFontMetrics();
                    int labelWidth = metrics.stringWidth(xLabel);
                    g2.drawString(xLabel, x0 - labelWidth / 2, y0 + metrics.getHeight() + 3);
                }
                g2.drawLine(x0, y0, x1, y1);
            }
        }

        // create x and y axes 
        g2.drawLine(padding + labelPadding, getHeight() - padding - labelPadding, padding + labelPadding, padding);
        g2.drawLine(padding + labelPadding, getHeight() - padding - labelPadding, getWidth() - padding, getHeight() - padding - labelPadding);

        Stroke oldStroke = g2.getStroke();
        g2.setColor(lineColor);
        g2.setStroke(GRAPH_STROKE);
        for (int i = 0; i < graphPoints.size() - 1; i++) {
            int x1 = graphPoints.get(i).x;
            int y1 = graphPoints.get(i).y;
            int x2 = graphPoints.get(i + 1).x;
            int y2 = graphPoints.get(i + 1).y;
            g2.drawLine(x1, y1, x2, y2);
        }

        g2.setStroke(oldStroke);
        g2.setColor(pointColor);
        for (int i = 0; i < graphPoints.size(); i++) {
            int x = graphPoints.get(i).x - pointWidth / 2;
            int y = graphPoints.get(i).y - pointWidth / 2;
            int ovalW = pointWidth;
            int ovalH = pointWidth;
            g2.fillOval(x, y, ovalW, ovalH);
        }
    }

//    @Override
//    public Dimension getPreferredSize() {
//        return new Dimension(width, heigth);
//    }
    private double getMinScore() {
        double minScore = Double.MAX_VALUE;
        for (Double score : scores) {
            minScore = Math.min(minScore, score);
        }
        return minScore;
    }

    private double getMaxScore() {
        double maxScore = Double.MIN_VALUE;
        for (Double score : scores) {
            maxScore = Math.max(maxScore, score);
        }
        return maxScore;
    }

    public void setScores(List<Double> scores) {
        this.scores = scores;
        invalidate();
        this.repaint();
    }

    public List<Double> getScores() {
        return scores;
    }

    private static void createAndShowGui() {
        List<Double> scores = new ArrayList<>();
        Random random = new Random();
        int maxDataPoints = 40;
        int maxScore = 10;
        for (int i = 0; i < maxDataPoints; i++) {
            scores.add((double) random.nextDouble() * maxScore);
//            scores.add((double) i);
        }
        GraphPanel mainPanel = new GraphPanel(scores);
        mainPanel.setPreferredSize(new Dimension(800, 600));
        JFrame frame = new JFrame("DrawGraph");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().add(mainPanel);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

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

It looks like this:

它看起来像这样:

#3

Or simply use the JFreechart library - http://www.jfree.org/jfreechart/ .

或者简单地使用JFreechart库http://www.jfree.org/jfreechart/。

#4

There exist many open source projects that handle all the drawing of line charts for you with a couple of lines of code. Here's how you can draw a line chart from data in a couple text (CSV) file with the XChart library. Disclaimer: I'm the lead developer of the project.

有许多开源项目，它们用几行代码为您处理所有的线图。以下是使用XChart库从一对文本(CSV)文件中的数据绘制线形图的方法。免责声明:我是这个项目的主要开发者。

In this example, two text files exist in ./CSV/CSVChartRows/. Notice that each row in the files represents a data point to be plotted and that each file represents a different series. series1 contains x, y, and error bar data, whereas series2 contains just x and y, data.

在本例中，./CSV/CSVChartRows/中存在两个文本文件。注意，文件中的每一行表示要绘制的数据点，每个文件表示不同的系列。series1包含x、y和error bar数据，而series2只包含x和y数据。

series1.csv

1,12,1.4
2,34,1.12
3,56,1.21
4,47,1.5

series2.csv

1,56
2,34
3,12
4,26

Source Code

public class CSVChartRows {

  public static void main(String[] args) throws Exception {

    // import chart from a folder containing CSV files
    XYChart chart = CSVImporter.getChartFromCSVDir("./CSV/CSVChartRows/", DataOrientation.Rows, 600, 400);

    // Show it
    new SwingWrapper(chart).displayChart();
  }
}

Resulting Plot

#5

Override the paintComponent method of your panel so you can custom draw. Like this:

重写面板的paintComponent方法，以便自定义绘制。是这样的:

@Override
public void paintComponent(Graphics g) {
    Graphics2D gr = (Graphics2D) g; //this is if you want to use Graphics2D
    //now do the drawing here
    ...
}

#6

Hovercraft Full Of Eels' answer is very good, but i had to change it a bit in order to get it working on my program:

气垫船装满鳗鱼的答案很好，但为了让它能在我的程序中工作，我不得不稍微改变一下。

int y1 = (int) ((this.height - 2 * BORDER_GAP) - (values.get(i) * yScale - BORDER_GAP));

instead of

而不是

int y1 = (int) (scores.get(i) * yScale + BORDER_GAP);

because if i used his way the graphic would be upside down

因为如果我用他的方式，图形会颠倒

(you'd see it if you used hardcoded values (e.g 1,3,5,7,9) instead of random values)

(如果使用硬编码的值，您会看到它。g 1 3 5 7 9)而不是随机值)