从文件中绘制线条

Question

>我需要制作GUI应用程序，该应用程序从用户选择的文件中获取坐标，并使用.drawLine与它们一起划线。我试图将这些点保存到 ArrayList，然后初始化它们，但我不知道如何继续并使其正常工作。请帮助我。

该文件看起来像这样，可以采用任何类型。

• 2,4,3,8 (x1， y1， x2， y2(
• 8,0,7,20
• 0,0,800,962

这是最有效的代码。

public class Line extends JPanel {
        ArrayList<Integer> points = new ArrayList<>();
        public Line() {
            points.add(20);
            points.add(40);
            points.add(250);
            points.add(40);
        }
        public void paintComponent(Graphics g) {
            Graphics2D g2d = (Graphics2D) g;
            for (int i = 0; i < points.size(); i++) {
                g2d.drawLine(points.get(i), points.get(i), points.get(i), points.get(i));
                System.out.println(points.get(i));
            }
        }
    }

Answer 1

因此，首先读取文件，然后添加到列表中。

此外，它只是绘制循环的点的cos。当它循环时，如果第一个数字是 8，你的循环绘制的是g2d.drawLine(8,8,8,8);

这是我的代码片段。未测试，但应该工作正常：

ArrayList<Integer> points = new ArrayList<>();
public Line(String filePath) {
    points = readFile(filePath);
}
public void paintComponent(Graphics g) {
    Graphics2D g2d = (Graphics2D) g;
    if(points!= null && points.size()>=4) {
        g2d.drawLine(points.get(0), points.get(1), points.get(2), points.get(3));
    }
}
public ArrayList<Integer> readFile(String filePath){
    BufferedReader br = null;
    FileReader fr = null;
    ArrayList<Integer> list = new ArrayList();
    try {
        //br = new BufferedReader(new FileReader(FILENAME));
        fr = new FileReader(filePath);
        br = new BufferedReader(fr);
        String sCurrentLine;
        while ((sCurrentLine = br.readLine()) != null) {
            String[] splitted = sCurrentLine.split(",");
            for (int i = 0; i < splitted.length; i++) {
                try {
                    list.add(Integer.parseInt(splitted[i].trim()));
                }
                catch (Exception ex){
                    System.out.println(splitted[i] + " is not a valid number/integer");
                }
            }
        }
        System.out.println(list);
    }
    catch (IOException e) {
        e.printStackTrace();
    } finally {
        try {
            if (br != null)
                br.close();
            if (fr != null)
                fr.close();
        } catch (IOException ex) {
            ex.printStackTrace();
        }
    }
    return list;
}

Answer 2

下面是如何读取文件并存储线条信息，然后绘制它们的示例。

为了方便起见，它使用Graphics2D的draw(Shape(方法，因此您可以在读取文件时直接存储Shape对象。

import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Shape;
import java.awt.geom.Line2D;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.Scanner;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Line extends JPanel {
    ArrayList<Shape> lines = new ArrayList<>();
    public Line() {
        try (Scanner scanner = new Scanner(new File("path_to_your_file"))) {
            while (scanner.hasNextLine()) {
            // split the line on the comma separator    
            String[] parts = scanner.nextLine().trim().split("\,");
            // read the coordinates
            int x1 = Integer.valueOf(parts[0]);
            int y1 = Integer.valueOf(parts[1]);
            int x2 = Integer.valueOf(parts[2]);
            int y2 = Integer.valueOf(parts[3]);
            // create a Line and store it
            lines.add(new Line2D.Float(x1, y1, x2, y2));
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
    }
    public void paintComponent(final Graphics g) {
        Graphics2D g2d = (Graphics2D) g;
        // draw all the lines
        for (Shape line : lines) {
            g2d.draw(line);
        }
    }
}