Java上机题目及答案代码.doc

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1、Four short words sum up what has lifted most successful individuals above the crowd: a little bit more.-author-dateJava上机题目及答案代码Java上机题目及答案代码Java上机实践三实验题目1假设字符串s1、s2、s3的定义如下：String s1 = “A String”;String s2 = “A String”;String s3 = s1;请写出下列表达式的值：s1 = s2s1 = s3s1.length()s1.equals(s2)s1.equals(s3)par

2、eTo(s2)pareTo(s3)s1.concat(s3)s1.indexOf(t)s3.lastIndexOf(t)实验目的（1） 熟悉字符串类String。（2） 学习创建类String的对象。（3） 学习使用类String执行字符串操作。实验步骤（1） 按题目的要求创建String对象s1、s2，并声明对象引用s3指向s1；（2） 调用String类的相关方法，执行指定操作并输出结果。package lab1;public class Showstr public static void main(String args)String s1 =A String;String s2 =A

3、 String;String s3 = s1;System.out.println(s1 = s2);System.out.println(s1 = s3);System.out.println(s1.length();System.out.println(s1.equals(s2);System.out.println(s1.equals(s3);System.out.println(pareTo(s2);System.out.println(pareTo(s3);System.out.println(s1.concat(s3);System.out.println(s1.indexOf(t

4、);System.out.println(s3.lastIndexOf(t);实验2 Java异常处理一、实验目的1）掌握Java异常的概念及工作机制2）掌握异常的分类3）掌握抛出异常语句的使用(throw)4）掌握抛出捕获处理异常语句的使用(trycatchfinally)5）掌握上抛异常语句的使用(throws)6）掌握创建自定义异常二、实验环境JDK1.6+Eclpise3.2三、实验内容1、编写一个应用程序，要求从键盘输入一个double型的圆的半径，计算并输出其面积。测试当输入的数据不是double型数据（如字符串“abc”）会产生什么结果，怎样处理。package lab2;imp

5、ort java.util.InputMismatchException;import java.util.Scanner;public class Err_1 public static void main(String args)Scanner reader=new Scanner(System.in);double r;tryr=reader.nextDouble();System.out.println(3.14*r*r);/System.out.println(3.14*r*r);catch(InputMismatchException e)System.out.println(数据

6、类型错误+e.toString();2、计算两个正数之和，当任意一个数超出范围时，抛出自己定义的异常（NumberRangeException）。package lab2;import java.util.Scanner;import piler.sym;class NumberRangeException extends ExceptionNumberRangeException(String msg)super(msg);public class Err_2 public static void main(String args)Scanner reader=new Scanner(Sys

7、tem.in);tryint a=reader.nextInt(); int b=reader.nextInt(); if(a=0|b=0) NumberRangeException e=new NumberRangeException(The number beyond range!); throw e; System.out.println(a+b);catch(NumberRangeException e)System.out.println(e.toString();实验3 输入和输出 1实验目的 了解流式输入输出的基本原理；掌握类File、FileInputStream、FileOu

8、tputStream的使用方法。 2实验内容 （1）编程：检查C:WINDOWSsetuplog.txt文件是否存在，若在则显示该文件的名称和内容。 package lab3;import java.io.File;import java.io.IOException;import java.util.Scanner;public class Inoutprivate static Scanner in;public static void main(String args)throws IOExceptiontryFile f1=new File(C:WINDOWSsetuplog.txt)

9、;System.out.println(Do this file exist?t+f1.exists();System.out.println(f1.getName();in = new Scanner(new File(C:WINDOWSsetuplog.txt); while (in.hasNextLine() String str = in.nextLine(); System.out.println(str); catch(IOException e)System.out.println(e.getMessage();（2）编程：输入5个学生的信息（包含学号、姓名、3科成绩），统计各学

10、生的总分，然后将学生信息和统计结果存入二进制数据文件STUDENT.DAT中。3实验要求 编程时，应考虑异常处理。package lab3;import java.io.FileOutputStream;import java.io.IOException;import java.io.ObjectOutputStream;import java.io.RandomAccessFile;import java.util.Scanner;import javafx.beans.value.WritableObjectValue;class StudentString snum;String na

11、me;int a,b,c,sum;public void Info()Scanner reader=new Scanner(System.in);System.out.println(Please enter the name:);name=reader.next();System.out.println(Please enter the student number:);snum=reader.next();System.out.println(Please enter three coursessorce:);a=reader.nextInt();b=reader.nextInt();c=

12、reader.nextInt();sum=a+b+c;reader.close();public class Inout_2public static void main(String args)throws IOExceptiontryFileOutputStream raf=new FileOutputStream(dari.txt,true);ObjectOutputStream out=new ObjectOutputStream(raf);Student stu=new Student5;for(int i=0;i5;i+)stui=new Student();(stui).Info

13、();out.writeObject(stui);out.close();catch(IOException ioe)System.out.println(ioe);catch(Exception e)System.out.println(e);实验题目4设计计算器的GUI界面，理解使用Java中的布局管理器。package lab4; import java.awt.FlowLayout;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import java.awt.event.WindowEven

14、t;import java.awt.event.WindowListener;import java.util.ArrayList; import javax.swing.JButton;import javax.swing.JFrame;import javax.swing.JTextArea; public class MyFrame extends JFrame private JButton btn0=new JButton(0); private JButton btn1=new JButton(1); private JButton btn2=new JButton(2); pri

15、vate JButton btn3=new JButton(3); private JButton btn4=new JButton(4); private JButton btn5=new JButton(5); private JButton btn6=new JButton(6); private JButton btn7=new JButton(7); private JButton btn8=new JButton(8); private JButton btn9=new JButton(9); private JButton btnpoint=new JButton(.); pri

16、vate JButton btnsqrt=new JButton(); private JButton btnadd=new JButton(+); private JButton btnsub=new JButton(-); private JButton btnmul=new JButton(*); private JButton btndiv=new JButton(/); private JButton btnback=new JButton(); private JButton btnsin=new JButton(sin); private JButton btnequ=new J

17、Button(=); private JButton btnclear=new JButton(CE); private JTextArea input=new JTextArea(2,21); private JTextArea show=new JTextArea(Result:n,2,21); private String result=; private ArrayList signpos=new ArrayList(); public MyFrame(String title) this(); setTitle(title); private MyFrame() setLayout(

18、new FlowLayout(FlowLayout.LEADING); setSize(250, 250); setResizable(false); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); setLocationRelativeTo(null);/ show.setEditable(false); input.setEditable(false); add(input); add(show); add(btn7); add(btn8); add(btn9); add(btndiv); add(btnsqrt); add(btn4); a

19、dd(btn5); add(btn6); add(btnmul); add(btnback); add(btn1); add(btn2); add(btn3); add(btnsub); add(btnclear); add(btn0); add(btnpoint); add(btnsin); add(btnadd); add(btnequ); btn0.addActionListener(new ActionListener() Override public void actionPerformed(ActionEvent e) input.setText(input.getText()+

20、0); ); btn1.addActionListener(new ActionListener() Override public void actionPerformed(ActionEvent e) input.setText(input.getText()+1); ); btn2.addActionListener(new ActionListener() Override public void actionPerformed(ActionEvent e) input.setText(input.getText()+2); ); btn3.addActionListener(new

21、ActionListener() Override public void actionPerformed(ActionEvent e) input.setText(input.getText()+3); ); btn4.addActionListener(new ActionListener() Override public void actionPerformed(ActionEvent e) input.setText(input.getText()+4); ); btn5.addActionListener(new ActionListener() Override public v

22、oid actionPerformed(ActionEvent e) input.setText(input.getText()+5); ); btn6.addActionListener(new ActionListener() Override public void actionPerformed(ActionEvent e) input.setText(input.getText()+6); ); btn7.addActionListener(new ActionListener() Override public void actionPerformed(ActionEvent e)

23、 input.setText(input.getText()+7); ); btn8.addActionListener(new ActionListener() Override public void actionPerformed(ActionEvent e) input.setText(input.getText()+8); ); btn9.addActionListener(new ActionListener() Override public void actionPerformed(ActionEvent e) input.setText(input.getText()+9);

24、 ); btnpoint.addActionListener(new ActionListener() Override public void actionPerformed(ActionEvent e) input.setText(input.getText()+.); ); btnadd.addActionListener(new ActionListener() Override public void actionPerformed(ActionEvent e) signpos.add(input.getText().length(); input.setText(input.get

25、Text()+); ); btnsub.addActionListener(new ActionListener() Override public void actionPerformed(ActionEvent e) signpos.add(input.getText().length(); input.setText(input.getText()+-); ); btnmul.addActionListener(new ActionListener() Override public void actionPerformed(ActionEvent e) signpos.add(inpu

26、t.getText().length(); input.setText(input.getText()+*); ); btndiv.addActionListener(new ActionListener() Override public void actionPerformed(ActionEvent e) signpos.add(input.getText().length(); input.setText(input.getText()+/); ); btnsin.addActionListener(new ActionListener() Override public void a

27、ctionPerformed(ActionEvent e) double res; if(!input.getText().isEmpty()/!input.getText().equals() /!input.getText()= error! res=Double.parseDouble(input.getText(); show.setText(sin +input.getText()+ = +Math.sin(res); input.setText(); else if(!result.isEmpty() res=Double.parseDouble(result); show.set

28、Text(sin +result+ = +Math.sin(res); input.setText(); ); btnequ.addActionListener(new ActionListener() Override public void actionPerformed(ActionEvent e) String in=input.getText(); if(signpos.size()=0) return; double first; String tmp=; if(in.charAt(0)=+|in.charAt(0)=-|in.charAt(0)=*|in.charAt(0)=/)

29、 first=Double.parseDouble(result); tmp=result.substring(result.indexOf(=)+1); else first=Double.parseDouble(in.substring(0, signpos.get(0); result=String.valueOf(operator(first,0,in); show.setText(tmp+in+ = +result); input.setText(); signpos.clear(); ); btnsqrt.addActionListener(new ActionListener()

30、 Override public void actionPerformed(ActionEvent e) double res; if(!input.getText().isEmpty()/!input.getText().equals() /!input.getText()= error! res=Double.parseDouble(input.getText(); show.setText(Sqrt +input.getText()+ = +Math.sqrt(res); input.setText(); else if(!result.isEmpty() res=Double.pars

31、eDouble(result); show.setText(Sqrt +result+ = +Math.sqrt(res); input.setText(); ); btnback.addActionListener(new ActionListener() Override public void actionPerformed(ActionEvent e) String in=input.getText(); if(in.isEmpty() return; input.setText(in.substring(0, in.length()-1); if(in.endsWith(+)|in.

32、endsWith(-)|in.endsWith(*)|in.endsWith(/) signpos.remove(signpos.size()-1); ); btnclear.addActionListener(new ActionListener() Override public void actionPerformed(ActionEvent e) input.setText(); signpos.clear(); ); private double operator(double operA,int i,String str) double operB=i=signpos.size()

33、-1?Double.parseDouble(str.substring(signpos.get(i)+1) :Double.parseDouble(str.substring(signpos.get(i)+1,signpos.get(i+1); switch(str.charAt(signpos.get(i) case +: operA+=operB; break; case -: operA-=operB; break; case *: operA*=operB; break; case /: operA/=operB; break; if(i=signpos.size()-1) return operA; else return operator(operA,i+1,str); public static void main(String args) MyFrame mf=new MyFrame(); mf.setVisible(true); -