import java.awt.BorderLayout;

import java.awt.Color;

import java.awt.Dimension;

import java.awt.Graphics;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import java.util.LinkedList;

import javax.swing.JButton;

import javax.swing.JComponent;

import javax.swing.JFrame;

import javax.swing.JPanel;

public class LinesComponent extends JComponent{

private static class Line{

final int x1;

final int y1;

final int x2;

final int y2;

final Color color;

public Line(int x1, int y1, int x2, int y2, Color color) {

this.x1 = x1;

this.y1 = y1;

this.x2 = x2;

this.y2 = y2;

this.color = color;

}

}

private final LinkedList<Line> lines = new LinkedList<Line>();

public void addLine(int x1, int x2, int x3, int x4) {

addLine(x1, x2, x3, x4, Color.black);

}

public void addLine(int x1, int x2, int x3, int x4, Color color) {

lines.add(new Line(x1,x2,x3,x4, color));

repaint();

}

public void clearLines() {

lines.clear();

repaint();

}

@Override

protected void paintComponent(Graphics g) {

super.paintComponent(g);

for (Line line : lines) {

g.setColor(line.color);

g.drawLine(line.x1, line.y1, line.x2, line.y2);

}

}

public static void main(String[] args) {

JFrame testFrame = new JFrame();

testFrame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);

final LinesComponent comp = new LinesComponent();

comp.setPreferredSize(new Dimension(1000, 1000));

testFrame.getContentPane().add(comp, BorderLayout.CENTER);

JPanel buttonsPanel = new JPanel();

JButton newLineButton = new JButton("New Line");

JButton clearButton = new JButton("Clear");

buttonsPanel.add(newLineButton);

buttonsPanel.add(clearButton);

testFrame.getContentPane().add(buttonsPanel, BorderLayout.SOUTH);

newLineButton.addActionListener(new ActionListener() {

@Override

public void actionPerformed(ActionEvent e) {

int x1 = (int) (Math.random()*1000);

int x2 = (int) (Math.random()*1000);

int y1 = (int) (Math.random()*1000);

int y2 = (int) (Math.random()*1000);

Color randomColor = new Color((float)Math.random(), (float)Math.random(), (float)Math.random());

comp.addLine(x1, y1, x2, y2, randomColor);

}

});

clearButton.addActionListener(new ActionListener() {

@Override

public void actionPerformed(ActionEvent e) {

comp.clearLines();

}

});

testFrame.pack();

testFrame.setVisible(true);

}

}