graphed.java

简单的java入门编程

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;

public class Graphed extends JFrame implements ChangeListener {
	
	int a,b,c,d;
	private JSlider aSlider,bSlider,cSlider,dSlider;
	private JTextField aText,bText,cText,dText;
	private JPanel panel;
	private int height =200,width=200;
	private JScrollPane scrollPane;
	
	public static void main (String[] args){
		Graphed frame=new Graphed();
		frame.setSize(320,350);
		frame.createGUI();
		frame.show();
		
	} 
	private void createGUI(){
		setDefaultCloseOperation(EXIT_ON_CLOSE);
		Container window=getContentPane();
		window.setLayout(new FlowLayout());
		
		aSlider=new JSlider(-5,5);
		aSlider.addChangeListener(this);
		window.add(aSlider);
		
		aText=new JTextField(4);
		window.add(aText);
		
		bSlider=new JSlider(-5,5);
		bSlider.addChangeListener(this);
		window.add(bSlider);
		
		bText=new JTextField(4);
		window.add(bText);
		
		cSlider=new JSlider(-5,5);
		cSlider.addChangeListener(this);
		window.add(cSlider);
		
		cText=new JTextField(4);
		window.add(cText);
		
		dSlider=new JSlider(-5,5);
		dSlider.addChangeListener(this);
		window.add(dSlider);
		
		dText=new JTextField(4);
		window.add(dText);
		
		panel =new JPanel();
		panel.setPreferredSize(new Dimension(width,height));
		panel.setBackground(Color.lightGray);
		window.add(panel);
		JScrollPane scrollPane =new JScrollPane(panel);
		window.add(scrollPane);
				
	}
	public void stateChanged(ChangeEvent e){
		a=aSlider.getValue();
		b=bSlider.getValue();
		c=cSlider.getValue();
		d=dSlider.getValue();
		aText.setText("a="+Integer.toString(a));
		bText.setText("b="+Integer.toString(b));
		cText.setText("c="+Integer.toString(c));
		dText.setText("d="+Integer.toString(d));
		draw();
		
	}
	private void draw (){
		Graphics paper=panel.getGraphics();
		paper.setColor(Color.white);
		paper.fillRect(0,0,width,height);
		double x,y,nextX,nextY;
		int xPixel,yPixel,nextXPixel,nextYPixel;
		paper.setColor(Color.black);
		for(xPixel=0;xPixel<=width;xPixel++){
			x=scaleX(xPixel);
			y=theFunction(x);
			yPixel=scaleY(y);
			nextXPixel=xPixel+1;
			nextX=scaleX(nextXPixel);
			nextY=theFunction(nextX);
			nextYPixel=scaleY(nextY);
			paper.drawLine(xPixel,yPixel,nextXPixel,nextYPixel);
		
		}
		
	}
	private double theFunction(double x){
		return a*x*x*x+b*x*x+c*x+d;
		
	}
	private double scaleX(int xPixel){
		double xStart=-5,xEnd=5;
		double xScale=width/(xEnd-xStart);
		return (xPixel-(width/2))/xScale;
			
	}
	private int scaleY(double y){
		double yStart=-5,yEnd=5;
		int pixelCoord;
		double yScale=height/(yEnd-yStart);
		pixelCoord=(int)(-y*yScale)+(int)(height/2);
		return pixelCoord;
		
		
	}
}