java 期末复习题目练习
1 打印出所有的"水仙花数"，所谓"水仙花数"是指一个三位数，其各位数字立方和等于该数本身。例如：153 是一个"水仙花数"，因为153=1的三次方＋5的三次方＋3的三次方。
package one;
public class Shuixianhua {
public static void main(String[] args) {
System.out.println("所有的水仙花数：");
for (int i = 100; i < 1000; i++) {
int ge,shi,bai;
bai=i/100;
shi=(i-100*bai)/10;
ge=i-bai*100-shi*10;
if(i==bai*bai*bai+shi*shi*shi+ge*ge*ge){
System.out.println(i+"");
}
}
}
}
2 建立一个长度为9的数组，随机为该数组分配九个0~100间的随机数作为数组元素，并顺序打印数组元素；然后实现数组反转，并打印反转后的数组元素。
package two;
import java.util.Random;
public class RandomNum {
public static void main(String[] args) {
int[] a=new int[9];
for (int i = 0; i < a.length; i++) {
a[i]=(int)(Math.random()*100)+1;
}
System.out.println("顺序输出随机数：");
for (int i = 0; i < a.length; i++) {
System.out.println("a["+i+"]="+a[i]);
}
for (int i = 0; i < a.length/2; i++) {
int temp=a[i];
a[i]=a[a.length-i-1];
a[a.length-i-1]=temp;
}
System.out.println("数组反转后：");
for (int i = 0; i < a.length; i++) {
System.out.println("a["+i+"]="+a[i]);
}
}
}
3 编写程序模拟体操比赛选手成绩的计算方法。首先输入五位评委各自的打分（满分100分），去掉一个最高分、去掉一个最低分后求平均分（保留小数点后两位）作为选手的最终成绩并输出。
package three;
import java.util.Scanner;
public class Score {
public static void main(String[] args) {
System.out.println("请各评委输入8号选手的成绩：");
Scanner in = new Scanner(System.in);
double a[] = new double[5];
for(int i=0; i<5; i++){
a[i]=in.nextDouble();
}
System.out.println("五位评委分别打分为：");
for(int i=0; i<5; i++)
System.out.print(" "+a[i]);
System.out.println();
double avg=0;
//对数组的值进行冒泡排序
for (int i = 1; i < a.length; i++) {
for (int j = 0; j < a.length-i; j++) {
if (a[j]>a[j+1]) {
double temp=a[j];
a[j]=a[j+1];
a[j+1]=temp;
}
}
}
for(int i=0; i<5; i++)
avg+=a[i];
System.out.println("8号选手的最终得分是："+((avg-a[a.length-1]-a[0])/5));
}
}
4 编写一个应用程序，用户分别从两个文本框输入学生的姓名和分数，程序按成绩排序将这些学生的姓名和分数显示在一个文本区中。
程序以及运行效果如图：
package four;
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.util.*;
public class StudentFrame extends JFrame{
JPanel pl;
JLabel name, score;
JTextField inputName, inputScore;
JButton button;
JScrollPane sp;
JTextArea showArea;
TreeSet treeSet;
StudentFrame(String title){
super(title);
treeSet = new TreeSet();
pl = new JPanel();
name = new JLabel("姓名");
score = new JLabel("成绩");
inputName = new JTextField(5);
inputScore = new JTextField(5);
button = new JButton("确定");
button.addActionListener(new MyListener());
pl.add(name);
pl.add(inputName);
pl.add(score);
pl.add(inputScore);
pl.add(button);
showArea = new JTextArea();
sp = new JScrollPane(showArea);
add(pl, BorderLayout.NORTH);
add(sp, BorderLayout.CENTER);
setSize(400,300);
setVisible(true);
validate();
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
class MyListener implements ActionListener{
public void actionPerformed(ActionEvent e){
String name = inputName.getText();
int score = 0;
try{
score = Integer.parseInt(inputScore.getText().trim());
if(name.length()>0){
Student stu = new Student(name, score);
treeSet.add(stu);
show(treeSet);
}
}catch(NumberFormatException nfe){
inputScore.setText("请输入数字字符");
}
}
public void show(TreeSet tree){
showArea.setText(null);
Iterator it = treeSet.iterator();
while(it.hasNext()){
Student stu = it.next();
showArea.append("姓名："+stu.getName()+" 成绩："+stu.getScore()+"\n");
}
}
}
public static void main(String[] args) {
new StudentFrame("学生成绩排序");
}
}
class Student implements Comparable{
String name;
int score;
Student(String name, int score){
this.name = name;
this.score = score;
}
public int getScore(){
return score;
}
public String getName(){
return name;
}
public int compareTo(Object b){
Student st = (Student)b;
int m = this.score - st.getScore();
if (m!=0)
return m;
else
return 1;
}
}
5 有10个U盘，有两个重要的属性：价格和容量。编写一个应用程序，使用TreeMap<>类，分别按照价格和容量排序输出10个U盘的详细信息。
package five;
import java.util.Collection;
import java.util.Iterator;
import java.util.TreeMap;
public class UDisk {
int amount;
double price;
UDisk(int amount, double price){
this.amount = amount;
this.price = price;
}
}
class UKey implements Comparable{
double key = 0;
UKey(double key){
this.key = key;
}
public int compareTo(Object b){
UKey bb = (UKey)b;
if(this.key == bb.key)
return -1;
else
return (int)((this.key-bb.key)*1000);
}
}
class E{
public static void main(String[] args) {
TreeMap treemap = new TreeMap();
int amount[] = {1, 2, 4, 8, 16, 32};
double price[] = {25, 18, 32, 80, 64, 120};
UDisk ud[] = new UDisk[6];
for(int i=0; i c = treemap.values();
Iterator it = c.iterator();
while(it.hasNext()){
UDisk d = it.next();
System.out.println("容量"+d.amount+"GB,"+d.price+"元");
}
treemap.clear();
System.out.println("--------------------------------------");
for(int i=0; i 
6 编写一个简易计算器，有一个标题为“简易计算器”的窗口。设计 “+”、“-”、“*”、“/”四种运算，另外，窗口中还有三个文本框。单击相应的按钮，将两个文本框的数字做运算，在第三个文本框中显示结果。要求处理NumberFormatException异常。程序运行效果如下图：
package six;
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
public class Calculator extends JFrame implements ActionListener{
JTextField text1, text2, text3;
JRadioButton btnAdd, btnSub, btnMul, btnDiv;
ButtonGroup bg;
JLabel num1, num2, result;
JButton solve;
Box base, boxH1, boxH2, boxH3, boxH4;
public Calculator(String name){
super(name);
setLayout(new FlowLayout());
text1 = new JTextField(10);
text2 = new JTextField(10);
text3 = new JTextField(10);
btnAdd = new JRadioButton("+");
btnSub = new JRadioButton("-");
btnMul = new JRadioButton("*");
btnDiv = new JRadioButton("/");
num1 = new JLabel("数一");
num2 = new JLabel("数二");
result = new JLabel("结果");
solve = new JButton("=");
solve.addActionListener(this);
bg = new ButtonGroup();
bg.add(btnAdd);
bg.add(btnSub);
bg.add(btnMul);
bg.add(btnDiv);
boxH1 = Box.createHorizontalBox();
boxH1.add(num1);
boxH1.add(Box.createHorizontalStrut(30));
boxH1.add(text1);
boxH2 = Box.createHorizontalBox();
boxH2.add(btnAdd);
boxH2.add(btnSub);
boxH2.add(btnMul);
boxH2.add(btnDiv);
boxH3 = Box.createHorizontalBox();
boxH3.add(num2);
boxH3.add(Box.createHorizontalStrut(30));
boxH3.add(text2);
boxH4 = Box.createHorizontalBox();
boxH4.add(result);
boxH4.add(Box.createHorizontalStrut(30));
boxH4.add(text3);
base = Box.createVerticalBox();
base.add(boxH1);
base.add(Box.createVerticalStrut(25));
base.add(boxH2);
base.add(Box.createVerticalStrut(25));
base.add(boxH3);
base.add(Box.createVerticalStrut(25));
base.add(solve);
base.add(Box.createVerticalStrut(25));
base.add(boxH4);
add(base);
setSize(300, 320);
setVisible(true);
validate();
setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
}
public void actionPerformed(ActionEvent e){
double n = 0;
double n1,n2;
try{
n1=Double.parseDouble(text1.getText());
n2=Double.parseDouble(text2.getText());
if(btnAdd.isSelected())
n = n1+n2;
else if(btnSub.isSelected())
n = n1-n2;
else if(btnMul.isSelected())
n = n1*n2;
else if(btnDiv.isSelected())
n = n1/n2;
text3.setText(String.valueOf(n));
}catch(NumberFormatException nfe){
text3.setText("请输入数字字符");
}
}
public static void main(String args[]){
new Calculator("简易计算器");
}
}
7 请写一个简易计时器。单击“开始”按钮启动计时器，并将计时时间显示在文本框中；单击“暂停”按钮暂停计时器；单击“继续”按钮重新启动计时器。程序运行效果如下图：
package seven;
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
public class MyTimer extends JFrame implements ActionListener {
JTextField text;
JButton bStart, bStop, bContinue;
Timer time;
int n = 0;
MyTimer(String name){
super(name);
time = new Timer(1000, this);
text = new JTextField(15);
bStart = new JButton("开始");
bStop = new JButton("暂停");
bContinue = new JButton("继续");
bStart.addActionListener(this);
bStop.addActionListener(this);
bContinue.addActionListener(this);
setLayout(new FlowLayout());
add(bStart);
add(bStop);
add(bContinue);
add(text);
setSize(300, 120);
setVisible(true);
validate();
setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
}
public void actionPerformed(ActionEvent e){
if(e.getSource()==time){
n = n + 1;
text.setText("计时："+ n +"秒");
}
else if(e.getSource()==bStart){
n = 0;
time.start();
}
else if(e.getSource()==bStop)
time.stop();
else if(e.getSource()==bContinue)
time.restart();
}
public static void main(String[] args) {
new MyTimer("简易计时器");
}
}
8 编写多线程程序，模拟多个人通过一个山洞。这个山洞每次只能通过一个人，每个人通过山洞的时间为2秒(sleep)。随机生成10个人，都要通过此山洞，用随机值对应的字符串表示人名，打印输出每次通过山洞的人名。提示：利用线程同步机制，过山洞用一条输出语句表示，该输出语句打印输出当前过山洞的人名，每个人过山洞对应一个线程，哪个线程执行这条输出语句，就表示哪个人过山洞。
package eight;
import java.util.Random;
public class PassCave implements Runnable{
public void run() {
synchronized (this) {
System.out.println(Thread.currentThread().getName()+"正在通过山洞");
try{
Thread.sleep(2000);
}catch(InterruptedException ie){
ie.printStackTrace();
}
}
}
public static String getRandomString(int length) { //length表示生成字符串的长度
String base = "abcdefghijklmnopqrstuvwxyz0123456789";
Random random = new Random();
StringBuffer sb = new StringBuffer();
for (int i = 0; i < length; i++) {
int number = random.nextInt(base.length());
sb.append(base.charAt(number));
}
return sb.toString();
}
public static void main(String[] args) {
PassCave pc = new PassCave();
Thread th[] = new Thread[10];
for(int i=0; i<10; i++){
th[i] = new Thread(pc);
th[i].setName(getRandomString(5));
th[i].start();
}
}
}
9 用两个线程玩猜数字游戏，第一个线程负责随机给出1~100之间的一个整数，第二个线程负责猜出这个数。要求每当第二个线程给出自己的猜测后，第一个线程都会提示“猜小了”、“猜大了”或“猜对了”。猜数之前，要求第二个线程要等待第一个线程设置好要猜测的数。第一个线程设置好猜测数之后，两个线程还要相互等待，其原则是：第二个线程给出自己的猜测后，等待第一个线程给出的提示；第一个线程给出提示后，等待给第二个线程给出猜测，如此进行，直到第二个线程给出正确的猜测后，两个线程进入死亡状态。
package nine;
public class GuessNumber {
public static void main(String args[]){
Number number = new Number();
number.giveNumberThread.start();
number.guessNumberThread.start();
}
}
class Number implements Runnable{
final int SMALLER = -1, LARGER = 1, SUCCESS = 8;
int realNumber, guessNumber, min = 0, max = 100, message = SMALLER;
boolean pleaseGuess = false, isGiveNumber = false;
Thread giveNumberThread, guessNumberThread;
Number(){
giveNumberThread = new Thread(this);
guessNumberThread = new Thread(this);
}
public void run(){
for(int count =1; true; count++){
setMessage(count);
if(message == SUCCESS)
return;
}
}
public synchronized void setMessage(int count){
if(Thread.currentThread() == giveNumberThread && isGiveNumber == false){
realNumber = (int)(Math.random()*100)+1;
System.out.println("随机给你一个1至100之间的数，猜猜是多少？");
isGiveNumber = true;
pleaseGuess = true;
}
if(Thread.currentThread() == giveNumberThread){
while(pleaseGuess == true)
try{
wait(); //让出CPU使用权，让另一个线程开始猜数
}catch(InterruptedException e){ }
if(realNumber > guessNumber){
message = SMALLER;
System.out.println("你猜小了！");
}
else if(realNumber < guessNumber){
message = LARGER;
System.out.println("你猜大了！");
}
else {
message = SUCCESS;
System.out.println("恭喜，你猜对了！");
}
pleaseGuess = true;
}
if(Thread.currentThread() == guessNumberThread && isGiveNumber == true){
while(pleaseGuess == false)
try{
wait(); //让出CPU使用权，让另一个线程开始猜数
}catch(InterruptedException e){ }
if(message == SMALLER){
min = guessNumber;
guessNumber = (min + max)/2;
System.out.println("我第"+count+"次猜这个数是"+guessNumber);
}
else if(message == LARGER){
max = guessNumber;
guessNumber = (min + max)/2;
System.out.println("我第"+count+"次猜这个数是"+guessNumber);
}
pleaseGuess = false;
}
notifyAll();
}
}
10 在电视节目中经常看见主持人提出的问题，并要求考试者在限定时间内回答问题。这里由程序提出问题，用户回答问题。问题保存在test.txt中，test.txt的格式如下。
每个问题提供A、B、C、D四个选择（单项选择）。
两个问题之间是用减号（-）尾加前一问题的答案分隔（例如：----D----）。
使用GUI界面，增加一个辅助限制答题时间的计时器线程，该线程限制用户必须在10秒内回答问题，一旦超过10秒，将进入下一题。程序运行效果如下图：
package ten;
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.io.*;
public class Exam extends JFrame implements ActionListener, ItemListener{
File test;
int MAX = 10;
int maxTime = MAX, score = 0;
javax.swing.Timer time;
JTextArea showQuestion;
JCheckBox choiceA, choiceB, choiceC, choiceD;
JLabel showScore, showTime;
String correctAnswer;
JButton reStart;
FileReader inOne;
BufferedReader inTwo;
Box base, boxH1, boxH2;
Exam(String title){
super(title);
time = new javax.swing.Timer(1000, this);
showQuestion = new JTextArea(2, 16);
setLayout(new FlowLayout());
showScore = new JLabel("分数"+score);
showTime = new JLabel(" ");
boxH1 = Box.createHorizontalBox();
boxH1.add(showTime);
boxH1.add(new JLabel("问题"));
boxH1.add(showQuestion);
choiceA = new JCheckBox("A");
choiceB = new JCheckBox("B");
choiceC = new JCheckBox("C");
choiceD = new JCheckBox("D");
choiceA.addItemListener(this);
choiceB.addItemListener(this);
choiceC.addItemListener(this);
choiceD.addItemListener(this);
boxH2 = Box.createHorizontalBox();
boxH2.add(choiceA);
boxH2.add(choiceB);
boxH2.add(choiceC);
boxH2.add(choiceD);
boxH2.add(showScore);
reStart = new JButton("再做一遍");
reStart.setEnabled(false);
reStart.addActionListener(this);
boxH2.add(reStart);
base = Box.createVerticalBox();
base.add(boxH1);
base.add(boxH2);
add(base);
setSize(400,200);
setVisible(true);
validate();
setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
}
public void setMAX(int n){
MAX = n;
}
public void setTestFile(File f){
test = f;
score = 0;
try{
inOne = new FileReader(test);
inTwo = new BufferedReader(inOne);
readOneQuestion();
reStart.setEnabled(false);
}catch(IOException e){
showQuestion.setText("没有选题");
}
}
public void readOneQuestion(){
showQuestion.setText(null);
try{
String s = null;
while((s=inTwo.readLine())!=null){
if(!s.startsWith("-"))
showQuestion.append("\n"+s);
else{
s = s.replaceAll("-", "");
correctAnswer = s;
break;
}
}
time.start();
if(s==null){
inTwo.close();
reStart.setEnabled(true);
showQuestion.setText("题目完毕");
time.stop();
}
}catch(IOException e){ }
}
public void itemStateChanged(ItemEvent e){
JCheckBox box = (JCheckBox)e.getSource();
String str = box.getText();
boolean bOne = box.isSelected();
boolean bTwo = str.compareToIgnoreCase(correctAnswer)==0;
if(bOne && bTwo){
score++;
showScore.setText("分数"+score);
time.stop();
maxTime = MAX;
readOneQuestion();
}
box.setSelected(false);
}
public void actionPerformed(ActionEvent e){
if(e.getSource()==time){
showTime.setText("剩："+maxTime+"秒");
maxTime--;
if(maxTime<=0){
maxTime = MAX;
readOneQuestion();
}
}
else if(e.getSource()==reStart)
setTestFile(test);
}
}
class Answer{
public static void main(String[] args) {
Exam win = new Exam("限时回答问题");
win.setTestFile(new File("D:\\","test.txt"));
win.setMAX(10);
}
}
