Java书上及实验内容编程答案.docx

1、Java书上及实验内容编程答案51页第3题 /3、求水仙花数public class Test public static void main(String args) for(int i =100 ; i = 1); sum = sum + k; i+; while(i = 100); System.out.println(1!+2!+.+100! = +sum); /Rectangle类:（第80面2）public class Rectangle double width; double length; Rectangle(double l,double w) check(w,l); wi

2、dth = w ; length = l ; public void check(double w,double l) if(w50|l50) System.out.print(长或宽超出规定范围!); System.exit(0); public double getArea() return this.length*this.width; public double getPerimeter() return (this.length+this.width)*2; public void Draw() for(int i = 1 ; i = this.width ; i+) for(int

3、 j = 1 ; j = this.length ; j+) if(i = 1|i = this.width) System.out.print(*); else if(j = 1| j=this.length) System.out.print(*); else System.out.print( ); System.out.print(n); /Test测试类:public class Test public static void main(String args) Rectangle rec = new Rectangle(10,5); System.out.println(面积:+r

4、ec.getArea(); System.out.println(周长：+rec.getPerimeter(); rec.Draw(); /Area接口（第116面2）public interface Area double CalsulateArea(); /MyCircle类public class MyCircle implements Area double radius; final double PI = 3.1415926; public MyCircle(double r) radius = r; public double CalsulateArea() return PI*

5、radius*radius; /MyRectangle类public class MyRectangle implements Areadouble width,height; public MyRectangle(double w , double h) width = w; height = h; public double CalsulateArea() return width*height; /Test测试类public class Test public static void main(String args) MyRectangle m = new MyRectangle(5,

6、6); MyCircle m1 = new MyCircle(10); System.out.println(正方形m的面积:+m.CalsulateArea()+n圆形m1的面积:+m1.CalsulateArea();151页题3public class Test public static void main(String args)int table = 4,1,3,5,9,2,1;/初始化;for(int i = 0; i table.length; i+) System.out.print(tablei+t);/未改变时输出; System.out.print(n); for(in

7、t i = 0; i table.length/2; i+)/进行变换; int temp; temp = tablei; tablei = tabletable.length-1-i; tabletable.length-1-i = temp; for(int i = 0; i 0) y = Math.sqrt(b*b-4*a*c); x1=(-b+y)/(2*a); x2=(-b-y)/(2*a); System.out.println(这个一元二次多项式有两个不相等的实根为：x1 =+x1+，x2 = +x2); else System.out.println(这个一元二次多项式方程无实

8、数解。); 实验3题2实验4题4class account int leftmoney; String id; public int getleftmoney() return leftmoney;public void savemoney(double money)leftmoney+=money;public void getmoney(double money)if(money=leftmoney)leftmoney-=money;elseSystem.out.println(只能取：+leftmoney); public static void main(String args) ac

9、count aa=new account(); aa.leftmoney=0; aa.id=1234567899; aa.savemoney(21000); System.out.println(存入21000元后余额为：+aa.getleftmoney(); aa.getmoney(11500); System.out.println(11500元后余额为：+aa.getleftmoney(); 实验6题1import java.util.HashMap;import java.util.Scanner;class Book public String name; public double

10、 price; public int num;public static class Num1 public static double getSum(HashMap books) double sum=0; for(int i=0;ibooks.size();i+) Book b=books.get(i); sum+=b.price*b.num; return sum; public static void main(String args) HashMap m=new HashMap(); System.out.println(输入5本书的名称、单价、购买数量:n); for(int i=

11、0;i5;i+) Book b=new Book(); Scanner a=new Scanner(System.in); b.name=a.nextLine(); b.price=a.nextDouble(); b.num=a.nextInt(); m.put(i,b); double sum=getSum(m); System.out.println(sum=+sum); 实验9题3的时刻是光标离开第一个文本框。package bag;import javax.swing.*;import java.awt.*;import java.awt.event.*;public class Te

12、xtFieldtest extends JFrame public static void main(String args) JFrame frame=new TextFieldtest(); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setVisible(true); JTextField first=new JTextField(); JTextField second=new JTextField(); JTextField result=new JTextField(); int n,m; TextFiel

13、dtest() super(TextFieldTest); setBounds(250, 200, 400, 200); setLayout(new FlowLayout(); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); first=new JTextField(input integer1); second=new JTextField(input integer2); result=new JTextField(Get the Result); /添加鼠标事件，使鼠标离开first时候检查*/ first.addMouseListener

14、(new MouseHander(first); second.addMouseListener(new MouseHander(second); result.addMouseListener(new MouseHander(result); /添加鼠标事件，方便输入数据和计算结果 result.addMouseMotionListener(new MouseMotionHander(); second.addMouseMotionListener(new MouseMotionHander(); first.setColumns(30); second.setColumns(30); re

15、sult.setColumns(30); add(first); add(second); add(result); private class MouseHander extends MouseAdapter public MouseHander(JTextField c) current=c; public void mousePressed(MouseEvent event) if(current=result) double firstNumber=Double.parseDouble(first.getText(); double secondNumber=Double.parseD

16、ouble(second.getText(); double Result=firstNumber+secondNumber; result.setText(+Result); else current.setText(); private JTextField current; private class MouseMotionHander extends MouseMotionAdapter public void mouseMoved(MouseEvent event) double number=Double.parseDouble(first.getText(); if(number200) int type=JOptionPane.ERROR_MESSAGE; JOptionPane.showMessageDialog(null,new String(输入数字必须在100200之间),提示, 2);