graphjframe.java

这是用JAVA语言编的小程序

package graphics;

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

public class GraphJFrame extends JFrame{      
    boolean add = false;
   private DrawPanel drawPanel;
   private JPanel displayPanel=new JPanel();
   private JTextField inputA=new JTextField(4);
   private JTextField inputB=new JTextField(4);
   private JTextField inputAA=new JTextField(4);
   private JTextField inputBB=new JTextField(4);
   private JButton button=new JButton("确定");
   private JButton button2=new JButton("叠加");

public GraphJFrame(){
        displayPanel.setBackground(Color.CYAN);
        displayPanel.setSize(getSize().width,900);
        inputA.setText("20");
        inputB.setText("80");
        inputAA.setText("20");
        inputBB.setText("80");
      
        displayPanel.add(new JLabel("绘制正弦曲线：y=b*sin*x/a),请输入a和b的值，a="));
        displayPanel.add(inputA);	
        displayPanel.add(new JLabel("b="));
        displayPanel.add(inputB);
        displayPanel.add(button);
        displayPanel.add(new JLabel("aa="));
        displayPanel.add(inputAA);
        displayPanel.add(new JLabel("bb="));
        displayPanel.add(inputBB);
        displayPanel.add(button2);      

        button.addActionListener(new ActionListener(){
              public void actionPerformed(ActionEvent e){
                              
                     drawPanel.repaint();
                
              }
         });
        //叠加
        button2.addActionListener(new ActionListener(){
              public void actionPerformed(ActionEvent e){                   
                  add=true;
                  drawPanel.repaint();
              
              }
         });

         getContentPane().setLayout(new BorderLayout());
         getContentPane().add(displayPanel,"North");
         drawPanel=new DrawPanel(this);

        //将当前对象传入DrawPanel类的构造函数中做后续处理
         getContentPane().add(drawPanel,"Center");
}
public static void main(String []args){
    GraphJFrame GJ = new GraphJFrame() ;
    GJ.setSize(800,400);
    GJ.setVisible(true);
    GJ.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE );
}

   double f(double x){
        double a=Double.valueOf(inputA.getText()).doubleValue();

        // Double.valueOf返回保存用参数字符串 s 表示的 double 值的 Double 对象。
        // Double.doubleValue()返回此 Double 对象的 double 值。所以这个函数是必须的

        double b=Double.valueOf(inputB.getText()).doubleValue();
        return (Math.sin(x/a)*b+getSize().height/2);
   }
   double f2(double x){

        double a=Double.valueOf(inputA.getText()).doubleValue();
        double b=Double.valueOf(inputB.getText()).doubleValue();
        double aa=Double.valueOf(inputAA.getText()).doubleValue();
        double bb=Double.valueOf(inputBB.getText()).doubleValue();
        return (Math.sin(x/(a+aa))*(b+bb)+getSize().height/2);
   }

}

class DrawPanel extends JPanel{
   /**
     * graApp不能直接引用 因为没有初始化
     * 并且使
     */  		
   GraphJFrame graApp;

    public DrawPanel(GraphJFrame owner){
          graApp=owner;
    }

    public void paintComponent(Graphics g){
        super.paintComponent(g);
        g.setColor(Color.ORANGE);
         g.clearRect(0,0,getSize().width,getSize().height);
        // 通过使用当前绘图表面的背景色进行填充来清除指定的矩形。
        if(graApp.add == false){
            for (int x = 0; x < getSize().width; x++) {

                g.drawLine(x, (int) (graApp.f(x)), x + 1, (int) (graApp.f(x + 1)));
            }
        }
             else {     
                   for (int x = 0; x < getSize().width; x++)
                   g.drawLine(x,  (int)(graApp.f2(x)),  x+1,(int)(graApp.f2(x+1)));   
                   graApp.add = false;	               
                 
              }   
        
  }
}