javaee基础教程习题答案

JAVAEE基础教程课后部分编程题答案

2-14 public class aa {

public static void main(String[] args) {

// TODO Auto-generated method stub

double x=34.5;

double y=68.4;

double z=x+y;

System.out.println("x+y="+x+"+"+y+"="+z);}

}

3-19

(一)从大到小

插入排序法

public class Sort {

public static void main(String[] args) {

int[] A={30,1,-9,70,25};

for(int i=1;i

for(int j=i;j>0;j--){

if(A[j]>A[j-1]){

int temp;

temp=A[j-1];

A[j-1]=A[j];

A[j]=temp;

}

}

}

System.out.println("利用插入排序方法的结果是：");

for(int i=0;i

System.out.print(A[i]+",");

}

}

}

选择排序法

public class S_sort {

public static void main(String[] args) {

int[] A={30,1,-9,70,25};

int max,temp;

for(int i=A.length-1;i>0;i--){

max=0;

for(int j=1;j<=i;j++){

if(A[max]>A[j])

max=j;

}

temp=A[max];

A[max]=A[i];

A[i]=temp;

}

System.out.println("利用选择排序方法的结果是：");

for(int i=0;i

System.out.print(A[i]+",");

}

}

}

（二）从小到大

import java.util.*;

public class rr {

public static void main(String[] args){

int A[]={30,1,-9,70,25};

Arrays.sort(A);

for(int i=0;i<5;i++){

System.out.print(A[i]+",");

}

}

}

3-11 public class pp {

public static void main(String[] args) {

int i,j,count=0;

for(j=2;j<=1000;j++){

for(i=2;i<=j/2;i++){

if(j%i==0)

break;

}

if(i>j/2)

{

count++;System.out.print(j+"\t");

if(count%5==0)

System.out.println(""); }

}

}

}

3-12 import java.util.Random;

public class rr {

public static void main(String[] args){

int count1=0,count2=0,count3=0,count4=0,count5=0,count6=0;

int temp;

Random r =new Random();

for(int i=1;i<=100;i++){

temp=r.nextInt()%6+1;

switch(temp){

case 1:count1++;break;

case 2:count2++;break;

case 3:count3++;break;

case 4:count4++;break;

case 5:count5++;break;

case 6:count6++;break;

}

}

System.out.println("count1="+count1);

System.out.println("count2="+count2);

System.out.println("count3="+count3);

System.out.println("count4="+count4);

System.out.println("count5="+count5);

System.out.println("count6="+count6);

}

}

3-13 public class rr {

public static void main(String[] args){

int sum=0,a=1;

for(int i=1;i<16;i++){

a=a*i;

sum+=a;

}

System.out.println("1!+2!+3!+...+15!="+sum);

}

}

3-16 public class r {

public static void main(String[] args) {

int[] prime=new int[30];

int i,j,m=0,count=0;

for(j=2;count<30;j++){

for(i=2;i<=j/2;i++){

if(j%i==0)

break;}

if(i>j/2){

count++;

prime[m]=j;

System.out.print(prime[m]+",");

}

}

}

}

3-18 import java.util.Scanner;

import java.util.*;

public class yy {

/**

* @param args

*/

public static void main(String[] args) { // TODO Auto-generated method stub

int[] d=new int[100];

int i=-1;

do{

System.out.println("输入整数(-2结束):");

Scanner input=new Scanner(System.in);

i++;

d[i]=input.nextInt();}

while(d[i]!=-2);

int[] dd=new int[i];

for(int j=0;j

{dd[j]=d[j];

}

Arrays.sort(dd);

System.out.print("输入值按从小到大的顺序排序是 ");

for(int a:dd)

System.out.print(a+" ");

}

}

6-12 import java.util.Calendar;

public class CalendarExample {

public static void main(String[] args) {

Calendar cal = Calendar.getInstance();

cal.add(Calendar.DATE, 10);

System.out.println("十天后的日期和时间：");

System.out.println(cal.get(Calendar.YEAR) + "年"

+ (cal.get(Calendar.MONTH)+1) + "月"

+ cal.get(Calendar.DATE) + "日"

+ cal.get(Calendar.HOUR) + ":"

+ cal.get(Calendar.MINUTE) + ":"

+ cal.get(Calendar.SECOND));

}

}

6-15 import java.util.HashMap;

import java.util.Map;

public class pp{

public static void main(String args[]){

Map map=new HashMap();

map.put("张三","90分");

map.put("李四", "83分");

System.out.println("所查的学生有:"+map.keySet());

System.out.println("张三的成绩为:"+map.get("张三"));

System.out.println("李四的成绩为:"+map.get("李四"));

System.out.println();

map.put("李四","100分");

System.out.println("修改后李四的成绩为:"+map.get("李四")); System.out.println();

System.out.println("两人最终成绩为:");

System.out.println("张三:"+map.get("张三"));

System.out.println("李四:"+map.get("李四"));

}

}

6-17

public class e {

public static void main(String[] args) {

long x=987654;

String str1=String.valueOf(x);//使用String类的valueOf()方法实现数值到字符串的转换

int y=365;

String str2=Integer.toString(y,16);//转换为十六进制

System.out.println("987654转换成字符串为:"+str1+"\n");

System.out.println("十进制365转换为十六进制为:"+str2);

}

}

6-21 import java.io.IOException;

import java.util.Scanner;

import java.util.List;

import java.util.ArrayList;

import java.util.InputMismatchException;

class Person{

private String name;

private int phone;

public String getName(){

return name;

}

public int getPhone(){

return phone;

}

public Person(String name,int phone){

https://www.360docs.net/doc/f011299975.html,=name;

this.phone=phone;

}

public String toString(){

return name+"的电话号码为:"+phone;

}

}

public class pp {

public static void main(String args[])throws IOException{ char m;

do{

List list=new ArrayList();

Scanner input=new Scanner(System.in);

System.out.println("请输入同学的姓名和联系方式：");

try { String Pname=input.next();

int Phone=input.nextInt();

Person LX=new Person(Pname,Phone);

list.add(LX);

for(Person p:list){

System.out.println(p); }

}

catch (InputMismatchException e1)

{System.out.println("警告：您输入的值不合理！");}

catch (Exception e2)

{System.out.println("警告：其它异常！");}

System.out.println("是否继续输入？ Y/N");

m = (char) System.in.read();

} while (m == 'y' || m == 'Y');

}

}

6-22 import java.util.HashMap;

import java.util.Map;

import java.util.Scanner;

public class pp {

public static void main(String[] args) {

Mapmap=new HashMap();

map.put("ample","足够的、宽敞的");

map.put("brisk", "轻快的、兴隆的");

map.put("deem","认为、视为");

map.put("doom","注定、劫数");

map.put("gossip","流言飞语");

map.put("lame","蹩脚的");

map.put("oath","誓言");

map.put("reap","收割、收获");

map.put("shabby","破旧的、不公正的");

map.put("ecology","生态、生态学");

while (true) {

Scanner sc = new Scanner(System.in);

System.out.println("请输入单词");

String str = sc.next();

System.out.println("你输入的单词的中文含义是："+"\t"+map.get(str));

}

}

}

8-10 import java.io.BufferedReader;

import java.io.IOException;

import java.io.FileReader;

import java.io.FileNotFoundException;

public class rr {

public String readfile() {

String str1 = "";

BufferedReader fr;

try {

fr = new BufferedReader(new FileReader("java.txt"));

String m = fr.readLine();

while (m != null) {

str1 += m + "\n";

m = fr.readLine();

StringBuffer s1=new StringBuffer(str1);

System.out.println(s1);

}

fr.close();

} catch (FileNotFoundException e) {

e.printStackTrace();

} catch (IOException e) {

e.printStackTrace();

}

return str1;

}

public static void main(String[] args) {

rr r= new rr();

String str1 = r.readfile();

StringBuffer str2=new StringBuffer(str1);

str2.reverse();

System.out.println(str2);

}

}

8-14 import java.io.BufferedReader;

import java.io.File;

import java.io.FileNotFoundException;

import java.io.FileReader;

import java.io.FileWriter;

import java.io.IOException;

import java.util.Arrays;

import java.util.Scanner;

class s {

public static void main(String[] args) {

try {

File f1=new File("file1.txt");

File f2=new File("file2.txt");

FileReader fr1=new FileReader(f1);

FileReader fr2=new FileReader(f2);

BufferedReader br1=new BufferedReader(fr1) ;

BufferedReader br2=new BufferedReader(fr2) ;

String len1=br1.readLine();

String len2=br2.readLine();

Scanner scan1=new Scanner(len1);

Scanner scan2=new Scanner(len2);

https://www.360docs.net/doc/f011299975.html,eDelimiter(",");

https://www.360docs.net/doc/f011299975.html,eDelimiter(",");

int[] I=new int[9];

for (int j=0; j <=4; j++) {

I[j] =scan1.nextInt();

}

for (int j=0; j <=3; j++) {

I[j+5] = scan2.nextInt();

}

Arrays.sort(I);

System.out.print(Arrays.toString(I));

fr1.close();

fr2.close();

File f3=new File("file3.text");

FileWriter fw=new FileWriter(f3);

for (int a : I)

{

fw.write(a+",");

}

fw.close();

} catch (FileNotFoundException e) {

e.printStackTrace();

} catch (IOException e) {

e.printStackTrace();

}

}

}

9-6

法一 class tt{

public static synchronized void ttt() {

int i=10;

while(true){

System.out.print(i++);

try{

Thread.sleep(500);

}catch (InterruptedException e) {

e.printStackTrace();

}

if (i==16){

System.out.println();

break;

}

System.out.print(",");

}

}

}

public class t implements Runnable {

public void run() {

tt.ttt();

}

public static void main(String[] args) {

Thread t1=new Thread(new t(),"xiancheng1"); Thread t2=new Thread(new t(),"xiancheng2"); t1.start();

t2.start();

}

}

法二 class Printnum {

public void shownum() {

int i = 10;

while (true) {

try {

System.out.print(i);

if (i == 15) {

System.out.println();

break;

}

System.out.print(",");

Thread.sleep(500);

} catch (InterruptedException e) {

e.printStackTrace();

}

i++;

}

}

}

public class Test9_6 implements Runnable {

private static Printnum myprint = new Printnum();

public void run() {

synchronized (myprint) {

myprint.shownum();

}

}

public static void main(String[] args) {

Thread t1 = new Thread(new Test9_6(), "线程1");

t1.start();

Thread t2 = new Thread(new Test9_6(), "线程2");

t2.start();

}

}

法三 class Print{

public static synchronized void print() {

for(int i=10;i<16;i++){

System.out.print(i+",");

try {

Thread.sleep(500);

} catch (InterruptedException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

}

}

public class t implements Runnable{

public static void main(String[] args) {

// TODO Auto-generated method stub

Thread t1=new Thread(new t());

Thread t2=new Thread(new t());

t1.start();

t2.start();

}

public void run() {

// TODO Auto-generated method stub

Print.print();

System.out.println("\n");

}

}

9-8（1）

public class MyThread extends Thread{

public static void main(String[] args) {

Thread t1 = new Thread();

Thread t2 = new MyThread();

Thread t3 = new MyThread();

t1.start();

t2.start();

t3.start();

}

public void run(){

for(char i=97;i<123;i++){

System.out.println(this.getName()+":"+i);

}

}

}

（2） //继承Thread类

class myshow extends Thread {

void show() {

for (char i = 97; i < 123; i++) {

System.out.print(this.getName() + ":" + i+"\t");

//System.out.print(Thread.currentThread().getName()+ ":" + c+"\t");

}

}

public void run() {

show();

}

}

public class myThread {

public static void main(String[] args) {

Thread t1 = new myshow();

Thread t2 = new myshow();

Thread t3 = new myshow();

t1.setName("线程1");

t2.setName("线程2");

t3.setName("线程3");

t1.start();

t2.start();

t3.start();

}

}

（3） //实现Runnable接口

class myshow implements Runnable {

void show() {

for (char i = 97; i < 123; i++) {

System.out.print(Thread.currentThread().getName()+ ":" + c+"\t");

}

}

public void run() {

show();

}

}

public class myThread {

public static void main(String[] args) {

Thread t1 = new myshow();

Thread t2 = new myshow();

Thread t3 = new myshow();

Thread t1 = new Thread(new myshow(), "线程1");

Thread t2 = new Thread(new myshow(), "线程2");

Thread t3 = new Thread(new myshow(), "线程3");

t1.start();

t2.start();

t3.start();

}

}