需要输入函数表达式生成相应的函数图，该怎么做？

3回答

MMTTMM

package math;import java.awt.BorderLayout;import java.awt.Dimension;import java.awt.GridLayout;import java.awt.Toolkit;import javax.swing.ButtonGroup;import javax.swing.JButton;import javax.swing.JComboBox;import javax.swing.JFrame;import javax.swing.JLabel;import javax.swing.JPanel;import javax.swing.JRadioButton;import javax.swing.JTextField;public class UI extends JFrame{MyPanel mp;JPanel pl = new JPanel();JPanel pl1 = new JPanel(),pl2 = new JPanel(),pl3 = new JPanel(),pl4 = new JPanel();JRadioButton rb1,rb2;ButtonGroup bg = new ButtonGroup();JTextField tf = new JTextField(16);String[] s = {"y = sin(x)", "y = cos(x)", "y = tan(x)","y = pow(x, 2)", "y = pow(x, 3)", "y = log(x)","y = pow(2, x)", "y = sqrt(x)", "r = a(sita)"};JComboBox cb;JButton bn1 = new JButton("变宽"),bn2 = new JButton("变窄"),bn3 = new JButton("拉长"),bn4 = new JButton("压短"),bn = new JButton("绘图"),exit = new JButton("退出"),bn5 = new JButton("左移"),bn6 = new JButton("右移"),bn7 = new JButton("上移"),bn8 = new JButton("下移");public UI(){mp = new MyPanel(this);pl1.setLayout(new GridLayout(1, 2));pl2.setLayout(new GridLayout(1, 2));pl3.setLayout(new GridLayout(1, 2));pl4.setLayout(new GridLayout(1, 2));pl1.add(bn1); bn1.setEnabled(false);pl1.add(bn2); bn2.setEnabled(false);pl2.add(bn3); bn3.setEnabled(false);pl2.add(bn4); bn4.setEnabled(false);pl3.add(bn5); bn5.setEnabled(false);pl3.add(bn6); bn6.setEnabled(false);pl4.add(bn7); bn7.setEnabled(false);pl4.add(bn8); bn8.setEnabled(false);pl.setLayout(new GridLayout(20, 1));rb1 = new JRadioButton("输入函数");rb2 = new JRadioButton("选择已有函数");rb2.setSelected(true);tf.setEnabled(false);bg.add(rb1); bg.add(rb2);rb1.addActionListener(mp);rb2.addActionListener(mp);pl.add(rb1);pl.add(tf);pl.add(rb2);cb = new JComboBox(s);pl.add(cb);pl.add(new JLabel());pl.add(pl1); pl.add(pl2);pl.add(pl3); pl.add(pl4);pl.add(bn);pl.add(exit);bn1.addActionListener(mp);bn2.addActionListener(mp);bn3.addActionListener(mp);bn4.addActionListener(mp);bn5.addActionListener(mp);bn6.addActionListener(mp);bn7.addActionListener(mp);bn8.addActionListener(mp);bn.addActionListener(mp);exit.addActionListener(mp);this.setLayout(new BorderLayout());this.add(mp, BorderLayout.CENTER);this.add(pl, BorderLayout.EAST);this.setTitle("平面直角坐标系画图小工具");this.setSize(797, 600 + 37);Dimension dn = Toolkit.getDefaultToolkit().getScreenSize();this.setLocation((dn.width - 797) / 2, (dn.height - 637) / 2);this.setVisible(true);this.setDefaultCloseOperation(3);}public static void main(String[] args){new UI();}}package math;import java.awt.Color;import java.awt.Graphics;import java.awt.Graphics2D;import java.awt.Point;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import java.awt.event.MouseEvent;import java.awt.event.MouseMotionListener;import java.awt.geom.Ellipse2D;import java.awt.geom.Line2D;import javax.swing.JOptionPane;import javax.swing.JPanel;public class MyPanel extends JPanel implements ActionListener,MouseMotionListener{UI ui;int flag;double h_times;int w_times;int dx;int dy;String str;Point pt = new Point(0, 0);void init(){flag = -1;h_times = Math.PI / 100;w_times = 100;dx = 300;dy = 300;}public MyPanel(UI ui){this.addMouseMotionListener(this);init();this.ui = ui;}public void paintComponent(Graphics g){super.paintComponent(g);Graphics2D g2 = (Graphics2D)g;drawCoordinate(g2);Line2D line;g2.setColor(Color.BLUE);g2.drawString("(" + (pt.x - 300) + ", " + (300 - pt.y) + ")", pt.x + 20, pt.y + 20);switch(flag){case 0:g2.drawString("y = Asin(Bx + C) + D", 105, 60);for(double i = 0; i < 600; i += 0.01){line = new Line2D.Double(i, dy - Math.sin(getReal_X(i)) * w_times, i + 1, dy - Math.sin(getReal_X(i + 1)) * w_times);g2.draw(line);}break;case 1:g2.drawString("y = Acos(Bx + C) + D", 105, 60);for(double i = 0; i < 600; i += 0.01){line = new Line2D.Double(i, dy - Math.cos(getReal_X(i)) * w_times, i + 1, dy - Math.cos(getReal_X(i + 1)) * w_times);g2.draw(line);}break;case 2:g2.drawString("y = Atan(Bx + C) + D", 105, 60);for(double i = 0; i < 600; i += 0.01){line = new Line2D.Double(i, dy - Math.tan(getReal_X(i)) * w_times, i + 1, dy - Math.tan(getReal_X(i + 1)) * w_times);g2.draw(line);}break;case 3:g2.drawString("y = Apow(Bx + C, 2) + D", 105, 60);for(double i = 0; i < 600; i += 0.01){line = new Line2D.Double(i, dy - Math.pow(getReal_X(i), 2) * w_times, i + 1, dy - Math.pow(getReal_X(i + 1), 2) * w_times);g2.draw(line);}break;case 4:g2.drawString("y = Apow(Bx + C, 3) + D", 105, 60);for(double i = 0; i < 600; i += 0.01){line = new Line2D.Double(i, dy - Math.pow(getReal_X(i), 3) * w_times, i + 1, dy - Math.pow(getReal_X(i + 1), 3) * w_times);g2.draw(line);}break;case 5:g2.drawString("y = Alog(Bx + C) + D", 105, 60);for(double i = 0; i < 600; i += 0.01){line = new Line2D.Double(i, dy - Math.log(getReal_X(i)) * w_times, i + 1, dy - Math.log(getReal_X(i + 1)) * w_times);g2.draw(line);}break;case 6:g2.drawString("y = Apow(2, Bx + C) + D", 105, 60);for(double i = 0; i < 600; i += 0.01){line = new Line2D.Double(i, dy - Math.pow(2, getReal_X(i)) * w_times, i + 1, dy - Math.pow(2, getReal_X(i + 1)) * w_times);g2.draw(line);}break;case 7:g2.drawString("y = Asqrt(Bx + C) + D", 105, 60);for(double i = 0; i < 600; i += 0.01){line = new Line2D.Double(i, dy - Math.sqrt(getReal_X(i)) * w_times, i + 1, dy - Math.sqrt(getReal_X(i + 1)) * w_times);g2.draw(line);}break;case 8:g2.drawString("y = a(sita)", 105, 60);for(double i = 0; i < 600; i += 0.01){line = new Line2D.Double(getReal_X(i) * Math.cos(getReal_X(i)), dy - getReal_X(i) * Math.sin(getReal_X(i)) * w_times, getReal_X(i) * Math.cos(getReal_X(i + 1)), dy - getReal_X(i) * Math.sin(getReal_X(i + 1)) * w_times);g2.draw(line);}break;}if(flag != -1){g2.drawString("A = " + w_times, 105, 90);g2.drawString("B= " + h_times, 105, 120);g2.drawString("C= " + (300 - dx), 105, 150);g2.drawString("D= " + (300 - dy), 105, 180);}}private double getReal_X(double x){return (x - dx) * h_times;}private void drawCoordinate(Graphics2D g2){int len = 20;Line2D line;for(int i = 0; i <= 600 / len; i++){g2.setColor(Color.PINK.darker());if(i == 300 / len)g2.setColor(Color.RED);else;line = new Line2D.Double(0, i * len, 600, i * len);g2.draw(line);line = new Line2D.Double(i * len, 0, i * len, 600);g2.draw(line);}drawPoint(g2, 300, 300);}private void drawPoint(Graphics2D g2, double x, double y){g2.setColor(Color.YELLOW);Ellipse2D circle = new Ellipse2D.Double(x - 2, y - 2, 4, 4);g2.fill(circle);}public void actionPerformed(ActionEvent e){if(e.getSource() == ui.rb1){ui.tf.setEnabled(true);ui.cb.setEnabled(false);flag = -1;}if(e.getSource() == ui.rb2){ui.tf.setEnabled(false);ui.cb.setEnabled(true);}if(e.getSource() == ui.bn1){h_times /= 1.1;}if(e.getSource() == ui.bn2){h_times *= 1.1;}if(e.getSource() == ui.bn3){// ui.bn4.setEnabled(true);w_times += 10;// if(w_times >= 300)// ui.bn3.setEnabled(false);}if(e.getSource() == ui.bn4){// ui.bn3.setEnabled(true);w_times -= 10;// if(w_times <= 0)// ui.bn4.setEnabled(false);}if(e.getSource() == ui.bn5){dx -= 10;}if(e.getSource() == ui.bn6){dx += 10;}if(e.getSource() == ui.bn7){// ui.bn8.setEnabled(true);dy -= 10;// if(dy <= 0)// ui.bn7.setEnabled(false);}if(e.getSource() == ui.bn8){// ui.bn7.setEnabled(true);dy += 10;// if(dy >= 600)// ui.bn8.setEnabled(false);}if(e.getSource() == ui.bn){if(ui.tf.isEnabled() == true){str = ui.tf.getText();if(str == null || str.length() == 0){ui.bn1.setEnabled(false);ui.bn2.setEnabled(false);ui.bn3.setEnabled(false);ui.bn4.setEnabled(false);ui.bn5.setEnabled(false);ui.bn6.setEnabled(false);ui.bn7.setEnabled(false);ui.bn8.setEnabled(false);JOptionPane.showMessageDialog(this, "请输入函数表达式 !");return;}}else flag = -2;ui.bn1.setEnabled(true);ui.bn2.setEnabled(true);ui.bn3.setEnabled(true);ui.bn4.setEnabled(true);ui.bn5.setEnabled(true);ui.bn6.setEnabled(true);ui.bn7.setEnabled(true);ui.bn8.setEnabled(true);init();if(ui.cb.isEnabled() == true){flag = ui.cb.getSelectedIndex();}}if(e.getSource() == ui.exit)System.exit(0);repaint();}public void mouseDragged(MouseEvent arg0){}public void mouseMoved(MouseEvent e){pt = e.getPoint();repaint();}}刚学java时写着玩的希望能够帮助到你！

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12345678_0001

java语言输入函数表达式生成相应的函数图像代码如下：import java.awt.BorderLayout;import java.awt.Dimension;import java.awt.GridLayout;import java.awt.Toolkit;import javax.swing.ButtonGroup;import javax.swing.JButton;import javax.swing.JComboBox;import javax.swing.JFrame;import javax.swing.JLabel;import javax.swing.JPanel;import javax.swing.JRadioButton;import javax.swing.JTextField;public class UI extends JFrame{MyPanel mp;JPanel pl = new JPanel();JPanel pl1 = new JPanel(),pl2 = new JPanel(),pl3 = new JPanel(),pl4 = new JPanel();JRadioButton rb1,rb2;ButtonGroup bg = new ButtonGroup();JTextField tf = new JTextField(16);String[] s = {"y = sin(x)", "y = cos(x)", "y = tan(x)","y = pow(x, 2)", "y = pow(x, 3)", "y = log(x)","y = pow(2, x)", "y = sqrt(x)", "r = a(sita)"};JComboBox cb;JButton bn1 = new JButton("变宽"),bn2 = new JButton("变窄"),bn3 = new JButton("拉长"),bn4 = new JButton("压短"),bn = new JButton("绘图"),exit = new JButton("退出"),bn5 = new JButton("左移"),bn6 = new JButton("右移"),bn7 = new JButton("上移"),bn8 = new JButton("下移");public UI(){mp = new MyPanel(this);pl1.setLayout(new GridLayout(1, 2));pl2.setLayout(new GridLayout(1, 2));pl3.setLayout(new GridLayout(1, 2));pl4.setLayout(new GridLayout(1, 2));pl1.add(bn1); bn1.setEnabled(false);pl1.add(bn2); bn2.setEnabled(false);pl2.add(bn3); bn3.setEnabled(false);pl2.add(bn4); bn4.setEnabled(false);pl3.add(bn5); bn5.setEnabled(false);pl3.add(bn6); bn6.setEnabled(false);pl4.add(bn7); bn7.setEnabled(false);pl4.add(bn8); bn8.setEnabled(false);pl.setLayout(new GridLayout(20, 1));rb1 = new JRadioButton("输入函数");rb2 = new JRadioButton("选择已有函数");rb2.setSelected(true);tf.setEnabled(false);bg.add(rb1); bg.add(rb2);rb1.addActionListener(mp);rb2.addActionListener(mp);pl.add(rb1);pl.add(tf);pl.add(rb2);cb = new JComboBox(s);pl.add(cb);pl.add(new JLabel());pl.add(pl1); pl.add(pl2);pl.add(pl3); pl.add(pl4);pl.add(bn);pl.add(exit);bn1.addActionListener(mp);bn2.addActionListener(mp);bn3.addActionListener(mp);bn4.addActionListener(mp);bn5.addActionListener(mp);bn6.addActionListener(mp);bn7.addActionListener(mp);bn8.addActionListener(mp);bn.addActionListener(mp);exit.addActionListener(mp);this.setLayout(new BorderLayout());this.add(mp, BorderLayout.CENTER);this.add(pl, BorderLayout.EAST);this.setTitle("平面直角坐标系画图小工具");this.setSize(797, 600 + 37);Dimension dn = Toolkit.getDefaultToolkit().getScreenSize();this.setLocation((dn.width - 797) / 2, (dn.height - 637) / 2);this.setVisible(true);this.setDefaultCloseOperation(3);}public static void main(String[] args){new UI();}}package math;import java.awt.Color;import java.awt.Graphics;import java.awt.Graphics2D;import java.awt.Point;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import java.awt.event.MouseEvent;import java.awt.event.MouseMotionListener;import java.awt.geom.Ellipse2D;import java.awt.geom.Line2D;import javax.swing.JOptionPane;import javax.swing.JPanel;public class MyPanel extends JPanel implements ActionListener,MouseMotionListener{UI ui;int flag;double h_times;int w_times;int dx;int dy;String str;Point pt = new Point(0, 0);void init(){flag = -1;h_times = Math.PI / 100;w_times = 100;dx = 300;dy = 300;}public MyPanel(UI ui){this.addMouseMotionListener(this);init();this.ui = ui;}public void paintComponent(Graphics g){super.paintComponent(g);Graphics2D g2 = (Graphics2D)g;drawCoordinate(g2);Line2D line;g2.setColor(Color.BLUE);g2.drawString("(" + (pt.x - 300) + ", " + (300 - pt.y) + ")", pt.x + 20, pt.y + 20);switch(flag){case 0:g2.drawString("y = Asin(Bx + C) + D", 105, 60);for(double i = 0; i < 600; i += 0.01){line = new Line2D.Double(i, dy - Math.sin(getReal_X(i)) * w_times, i + 1, dy - Math.sin(getReal_X(i + 1)) * w_times);g2.draw(line);}break;case 1:g2.drawString("y = Acos(Bx + C) + D", 105, 60);for(double i = 0; i < 600; i += 0.01){line = new Line2D.Double(i, dy - Math.cos(getReal_X(i)) * w_times, i + 1, dy - Math.cos(getReal_X(i + 1)) * w_times);g2.draw(line);}break;case 2:g2.drawString("y = Atan(Bx + C) + D", 105, 60);for(double i = 0; i < 600; i += 0.01){line = new Line2D.Double(i, dy - Math.tan(getReal_X(i)) * w_times, i + 1, dy - Math.tan(getReal_X(i + 1)) * w_times);g2.draw(line);}break;case 3:g2.drawString("y = Apow(Bx + C, 2) + D", 105, 60);for(double i = 0; i < 600; i += 0.01){line = new Line2D.Double(i, dy - Math.pow(getReal_X(i), 2) * w_times, i + 1, dy - Math.pow(getReal_X(i + 1), 2) * w_times);g2.draw(line);}break;case 4:g2.drawString("y = Apow(Bx + C, 3) + D", 105, 60);for(double i = 0; i < 600; i += 0.01){line = new Line2D.Double(i, dy - Math.pow(getReal_X(i), 3) * w_times, i + 1, dy - Math.pow(getReal_X(i + 1), 3) * w_times);g2.draw(line);}break;case 5:g2.drawString("y = Alog(Bx + C) + D", 105, 60);for(double i = 0; i < 600; i += 0.01){line = new Line2D.Double(i, dy - Math.log(getReal_X(i)) * w_times, i + 1, dy - Math.log(getReal_X(i + 1)) * w_times);g2.draw(line);}break;case 6:g2.drawString("y = Apow(2, Bx + C) + D", 105, 60);for(double i = 0; i < 600; i += 0.01){line = new Line2D.Double(i, dy - Math.pow(2, getReal_X(i)) * w_times, i + 1, dy - Math.pow(2, getReal_X(i + 1)) * w_times);g2.draw(line);}break;case 7:g2.drawString("y = Asqrt(Bx + C) + D", 105, 60);for(double i = 0; i < 600; i += 0.01){line = new Line2D.Double(i, dy - Math.sqrt(getReal_X(i)) * w_times, i + 1, dy - Math.sqrt(getReal_X(i + 1)) * w_times);g2.draw(line);}break;case 8:g2.drawString("y = a(sita)", 105, 60);for(double i = 0; i < 600; i += 0.01){line = new Line2D.Double(getReal_X(i) * Math.cos(getReal_X(i)), dy - getReal_X(i) * Math.sin(getReal_X(i)) * w_times, getReal_X(i) * Math.cos(getReal_X(i + 1)), dy - getReal_X(i) * Math.sin(getReal_X(i + 1)) * w_times);g2.draw(line);}break;}if(flag != -1){g2.drawString("A = " + w_times, 105, 90);g2.drawString("B= " + h_times, 105, 120);g2.drawString("C= " + (300 - dx), 105, 150);g2.drawString("D= " + (300 - dy), 105, 180);}}private double getReal_X(double x){return (x - dx) * h_times;}private void drawCoordinate(Graphics2D g2){int len = 20;Line2D line;for(int i = 0; i <= 600 / len; i++){g2.setColor(Color.PINK.darker());if(i == 300 / len)g2.setColor(Color.RED);else;line = new Line2D.Double(0, i * len, 600, i * len);g2.draw(line);line = new Line2D.Double(i * len, 0, i * len, 600);g2.draw(line);}drawPoint(g2, 300, 300);}private void drawPoint(Graphics2D g2, double x, double y){g2.setColor(Color.YELLOW);Ellipse2D circle = new Ellipse2D.Double(x - 2, y - 2, 4, 4);g2.fill(circle);}public void actionPerformed(ActionEvent e){if(e.getSource() == ui.rb1){ui.tf.setEnabled(true);ui.cb.setEnabled(false);flag = -1;}if(e.getSource() == ui.rb2){ui.tf.setEnabled(false);ui.cb.setEnabled(true);}if(e.getSource() == ui.bn1){h_times /= 1.1;}if(e.getSource() == ui.bn2){h_times *= 1.1;}if(e.getSource() == ui.bn3){// ui.bn4.setEnabled(true);w_times += 10;// if(w_times >= 300)// ui.bn3.setEnabled(false);}if(e.getSource() == ui.bn4){// ui.bn3.setEnabled(true);w_times -= 10;// if(w_times <= 0)// ui.bn4.setEnabled(false);}if(e.getSource() == ui.bn5){dx -= 10;}if(e.getSource() == ui.bn6){dx += 10;}if(e.getSource() == ui.bn7){// ui.bn8.setEnabled(true);dy -= 10;// if(dy <= 0)// ui.bn7.setEnabled(false);}if(e.getSource() == ui.bn8){// ui.bn7.setEnabled(true);dy += 10;// if(dy >= 600)// ui.bn8.setEnabled(false);}if(e.getSource() == ui.bn){if(ui.tf.isEnabled() == true){str = ui.tf.getText();if(str == null || str.length() == 0){ui.bn1.setEnabled(false);ui.bn2.setEnabled(false);ui.bn3.setEnabled(false);ui.bn4.setEnabled(false);ui.bn5.setEnabled(false);ui.bn6.setEnabled(false);ui.bn7.setEnabled(false);ui.bn8.setEnabled(false);JOptionPane.showMessageDialog(this, "请输入函数表达式 !");return;}}else flag = -2;ui.bn1.setEnabled(true);ui.bn2.setEnabled(true);ui.bn3.setEnabled(true);ui.bn4.setEnabled(true);ui.bn5.setEnabled(true);ui.bn6.setEnabled(true);ui.bn7.setEnabled(true);ui.bn8.setEnabled(true);init();if(ui.cb.isEnabled() == true){flag = ui.cb.getSelectedIndex();}}if(e.getSource() == ui.exit)System.exit(0);repaint();}public void mouseDragged(MouseEvent arg0){}public void mouseMoved(MouseEvent e){pt = e.getPoint();repaint();}}

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收到一只叮咚

这个方法是 java.io.DataOutput 接口中的一个方法。下面是 JDK1.5 中的参考：java.io接口 DataOutput所有已知子接口：ImageOutputStream, ObjectOutput所有已知实现类：DataOutputStream, FileCacheImageOutputStream, FileImageOutputStream, ImageOutputStreamImpl, MemoryCacheImageOutputStream, ObjectOutputStream, RandomAccessFilepublic interface DataOutputDataOutput 接口用于将任意 Java 基本类型转换为一系列字节，并将这些字节写入二进制流。同时还提供了一个将 String 转换成 UTF-8 修改版格式并写入所得到的系列字节的工具。再看 writeInt() 方法的说明：writeIntvoid writeInt(int v) throws IOException将一个 int 值写入输出流，该值由四个字节组成。要写入的字节值（按顺序显示）是：(byte)(0xff & (v >> 24))(byte)(0xff & (v >> 16))(byte)(0xff & (v >> 8))(byte)(0xff & v)此方法写入的字节可由 DataInput 接口的 readInt 方法读取，然后该方法将返回一个等于 v 的 int 值。参数：v - 要写入的 int 值。根据以上说明，这个方法用于把一个整型数据转换成 4 个字节的 byte ，然后写入二进制流。如果写入文件的话，那这个文件是二进制文件，而不是文本文件。在使用的时候，如果使用了 writeInt() 这类方法（writeDouble，writeFloat等），那么在读取的时候，必须使用实现了 DataInput 接口的输入流读取。而且要按照写入的顺序读取：例：package com.test;import java.io.BufferedInputStream;import java.io.BufferedOutputStream;import java.io.ByteArrayInputStream;import java.io.ByteArrayOutputStream;import java.io.DataInput;import java.io.DataInputStream;import java.io.DataOutput;import java.io.DataOutputStream;public class DataStream {public static void main(String[] args) {try{//下面是输出, 这里只是输出到内存ByteArrayOutputStream bos = new ByteArrayOutputStream();DataOutputStream dos = new DataOutputStream(new BufferedOutputStream(bos));dos.writeInt(22);dos.writeDouble(33.33);dos.writeLong(33l);dos.writeBoolean(true);dos.writeChar('a');dos.writeByte(33);dos.writeFloat(44.4f);dos.flush();//下面是输入，这里也只是从内存输入DataInputStream dis = new DataInputStream(new BufferedInputStream(new ByteArrayInputStream(bos.toByteArray())));System.out.println(dis.readInt());System.out.println(dis.readDouble());System.out.println(dis.readLong());System.out.println(dis.readBoolean());System.out.println(dis.readChar());System.out.println(dis.readByte());System.out.println(dis.readFloat());dis.close();bos.close();}catch(Exception e){}}}上面程序最后的打印语句，你可以调换顺序，结果应该会与你写入的不一样，也就是会造成读取错误，因些读取顺序要和写入的一样。

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