2013校园招聘java笔试题

记录一些找工作时碰到的笔试题。希望能对大家有帮助。

package Exam;

import java.util.Date;
import java.text.SimpleDateFormat;

/*
* 2013任子行校园招聘java笔试题
* 把Date类型转成指定格式的String
* 把二进制字符串转成int型
*/
public class DateString {

/**
* @param args
*/
public static String DateToString(Date date) {

SimpleDateFormat sd = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
//sd.applyPattern("yyyy-MM-dd HH:mm:ss");
String dateStr = sd.format(new Date());

System.out.println(dateStr);
return dateStr;
}

public static int StringToInt(String num) {
int result = 0;
for(int i = 0; i < num.length(); i++) {
//System.out.println("i = " + i);
result += (num.charAt(i)-48)<<(num.length()-i-1);
//System.out.println(Integer.valueOf(num.charAt(i)));

//System.out.println(result);
}
System.out.println(result);
return result;
}

public static int StringToInt1(String num) {

System.out.println(Integer.parseInt(num, 2));
return Integer.parseInt(num, 2);
}

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

DateToString(new Date());
StringToInt("1101");
StringToInt1("1101");

}

}

package Exam;

import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.Writer;

//任子行2013校园招聘 java笔试题
//把一个UTF-8编码文件转成GBK编码文件
public class EncodingTranser {

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

try {
changeEncoding("C:/Users/ldl/workspace/广州笔试/src/Exam/Joseph.java", "C:/gbk.txt");
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

public static void changeEncoding(String utf8File, String gbkFile) throws IOException {

String line_separator = System.getProperty("line.separator");
System.out.println(line_separator);
StringBuffer content = new StringBuffer();
FileInputStream fis = new FileInputStream(utf8File);
DataInputStream dis = new DataInputStream(fis);

BufferedReader br = new BufferedReader(new InputStreamReader(dis, "GBK"));

String line ;

while((line =br.readLine())!=null) {
content.append(line + line_separator);
}

br.close();
dis.close();
fis.close();

Writer osw = new OutputStreamWriter(new FileOutputStream(gbkFile), "utf-8");
osw.write(content.toString());
osw.close();
}
}

约瑟夫环问题，打印出每次出队人的编号

package Exam;

import java.util.Scanner;

/*
* 约瑟夫环问题，打印出每次出队人的编号
*/
public class Joseph {

private static class Node {
int no;
Node next;

public Node(int no) {
this.no = no;
}
}
public static void main(String[] args) {

Scanner scanner = new Scanner(System.in);

System.out.println("请输入总人数\n");
int total = scanner.nextInt();
System.out.println("请输入出队数\n");
int num = scanner.nextInt();

Node header = new Node(1); //头结点
Node pointer = header; //当前的节点

//构造循环链表
for(int i = 2; i <= total; i++) {
pointer.next = new Node(i);
pointer = pointer.next;
}
pointer.next = header;

//当链表中的节点数多于一个时，执行出队操作
while(pointer.next != pointer) {
for(int i = 1; i < num; i++) { //从当前节点开始数num-1次
pointer = pointer.next;
}
System.out.print(pointer.next.no + " "); //即将出队的人报数
pointer.next = pointer.next.next;     //下一个就是要出队的编号，让num-1指向num+1
}
System.out.print(pointer.no); //最后一个生存下来的人报数

//注意：程序结束前 关闭资源
scanner.close();
}

}

对List排序

package Exam;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

/**
* 2013任子行校园招聘java笔试题
* 排序：证件类型小的排在前面，如果证件类型相同，
* 证件号码小的排在前面
*/
class Human {
private String id_type;
private int id_num;

public Human(String id_type, int id_num) {
this.id_type = id_type;
this.id_num = id_num;
}

public String getId_type() {
return id_type;
}
public void setId_type(String id_type) {
this.id_type = id_type;
}
public int getId_num() {
return id_num;
}
public void setId_num(int id_num) {
this.id_num = id_num;
}
}

public class ListSort {

/**
* 这段代码要考生完成
* 调用Collections.sort(List, Comparator())
*/
public static void sorortList(List<Human> list) {
Collections.sort(list, new Comparator<Human>() {

@Override
public int compare(Human o1, Human o2) {
// TODO Auto-generated method stub
if(o1.getId_type().equals(o2.getId_type())) {
return Integer.valueOf(o1.getId_num()).compareTo
(Integer.valueOf(o2.getId_num()));
}
else
return o1.getId_type().compareTo(o2.getId_type());
}

});
}

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

List<Human> list = new ArrayList<Human>();
list.add(new Human("idCard", 366));
list.add(new Human("idCard", 361));
list.add(new Human("idCard", 363));
list.add(new Human("idCard", 362));
list.add(new Human("stuCard", 110));
list.add(new Human("stuCard", 120));
list.add(new Human("stuCard", 119));

for(Human human : list)
System.out.println("证件类型 " + human.getId_type()
+ "证件号码 " + human.getId_num());

sorortList(list);
System.out.println();

for(Human human : list)
System.out.println("证件类型 " + human.getId_type()
+ "证件号码 " + human.getId_num());
}

}

给定字符串，求其出现重复的最长子串

package Exam;

import java.util.Scanner;

/**
* 2013UC校园招聘试题
* 给定字符串，求其出现重复的最长子串
* 如drucwebejfucwebd中，最长子串是ucweb
*/
public class LRS {

/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner sc = new Scanner(System.in);
String src = sc.nextLine();

lrs(src);

//注意养成关闭资源的好习惯
sc.close();
}

private static int lrs(String src) {

int max = 0;
int startIndex = 0;

//从间隔为1开始，依次递增，查找连续重复子串
for(int distance = 1; distance < src.length(); distance++) {

//从第一个字符开始，和间隔distance的字符开始查找
for(int temp = 0,index = 0; index < src.length()-distance; index++) {

//如果两个字符相同，则temp递增；
if(src.charAt(index)==src.charAt(index+distance)) {
temp++;
}
//如果不同，temp从0开始重新计数
else {
temp = 0;
}

//如果当前累加temp比max大，则更新max
if(temp > max) {
max = temp;
//同时更新最长重复子串的起始的索引
startIndex = index-temp+1;
}
}
}

//打印最长重复子串
System.out.println("最长重复子串个数  " + max);

for(int i = 0; i < max; i++)
System.out.print(src.charAt(startIndex+i));
System.out.println();

return max;
}

}

package Exam;

import java.util.HashMap;
import java.util.Map;

/**
*
* 找出字符串中出现次数最多的单词，如果有多个最多的则返回null
* 如"how do you do"，返回do; 如"how old are you"，返回null;
*/
public class MostString {

/**
* @param args
*/

public static String findMost(String s) {

String[] rs = s.split(" ");

//		for(String str : rs)
//			System.out.print(str + " ");
//		System.out.println();

Map<String, Integer> map = new HashMap<String, Integer>();
int max = -1;
int value = 0;
String key = null;

//把各个单词放入HashMap,键为单词，值为单词出现的次数
for(String str : rs) {
if(map.containsKey(str)) {
value = map.get(str);
map.put(str, value+1);
}
else
map.put(str, 1);
if((value=map.get(str)) > max) {
max = value;
key = str;
}
}

//		for(Entry entry : map.entrySet())
//			System.out.println(entry.getKey() + " " + entry.getValue());
//		System.out.println();
//
//		System.out.println("max = " + max + ", key = " + key);

//先删除最大值对应的那个实体
map.remove(key);
//如果删除后还存在最大值的实体，则说明字符串中存在多个最大值
if(map.containsValue(max))
return null;
return key;
}

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

String str = "how do you do";
System.out.println(str);
System.out.println(findMost(str));

str= "how old are you";
System.out.println(str);
System.out.println(findMost(str));
}

}

package Exam;

/**
* 2013校园招聘3G门户java笔试题
* 两个线程，一个执行加法操作，一个执行减法操作
* 初始值为0，操作后的范围0或1
*/
class Mutex {
private static int i;

//没把Mutex声明为静态的:(
private static Mutex m = null;

private Mutex() {

}

public static Mutex getInstance() {
if(m == null)
m = new Mutex();
return m;
}

public synchronized void add() {
if(i!=0)
try {
wait();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
if(i==0) {
System.out.println(Thread.currentThread().getName()
+ ": " + (++i));
this.notifyAll();
}

}

public synchronized void minus() {
if(i!=1)
try {
wait();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
if(i==1) {
System.out.println(Thread.currentThread().getName()
+ ": " + --i);
this.notifyAll();
}

}

}

class Thread1 implements Runnable {

private Mutex m;

public Thread1(Mutex m) {
this.m = m;
}
@Override
public void run() {
// TODO Auto-generated method stub
for(int i = 0; i < 3; i++)
m.add();
}

}

class Thread2 implements Runnable {

private Mutex m;

public Thread2(Mutex m) {
this.m = m;
}
@Override
public void run() {
// TODO Auto-generated method stub
for(int i = 0; i < 3; i++)
m.minus();
}

}

public class OneOrZeroThread {

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

Mutex m = Mutex.getInstance();
Thread t1 = new Thread(new Thread1(m), "Thread1");
Thread t2 = new Thread(new Thread2(m), "Thread2");

t1.start();
t2.start();
}

}

package Exam;

/**
* 2013校园招聘迅雷java笔试题
* 三个线程各说的一句话，循环打印出10次
*
*/
public class PrintABC {
public static void main(String[] args) {
MajusculeABC maj = MajusculeABC.newInstance();
Thread t_a = new Thread(new Thread_ABC(maj , 'A', "i want to ask u."));
Thread t_b = new Thread(new Thread_ABC(maj , 'B', "Loved."));
Thread t_c = new Thread(new Thread_ABC(maj , 'C', "......"));
t_a.start();
t_b.start();
t_c.start();
}
}
class MajusculeABC {
private char charactor = 'A';

/* 限制此类只创建一个对象 */
private static MajusculeABC maObj =null;
private MajusculeABC() {}
public static MajusculeABC newInstance(){
if(maObj == null) {
maObj = new MajusculeABC();
}
return maObj;
}

public void setCharactor() {
this.charactor += 1;
if(this.charactor == 'D') {
this.charactor = 'A';
}
}
public char getCharactor() {
return this.charactor;
}

}
class Thread_ABC implements Runnable {

private MajusculeABC maj;
private char charactor = ' ';
private String dialog;

public Thread_ABC(MajusculeABC maj, char charactor, String dialog) {
this.maj = maj;
this.charactor = charactor;
this.dialog = dialog;
}

public void run() {
int i = 0;
while (i<10) {
synchronized (maj) {

while(this.charactor != maj.getCharactor()) {
try {
maj.wait();
} catch (InterruptedException e) {}
}

System.out.println(this.charactor + ":" +this.dialog);

i++;

maj.setCharactor();
maj.notifyAll();

}
}

}
}

package Exam;

/*
* 2013艾科校园招聘java笔试题
*/
public class ThreeToTen {

/**
* @param args
*/

public static int change(String s) {
int n = 0;

for(int i = 0; i < s.length(); i++) {
char c = s.charAt(i);
n = n + (c-48)*(int)Math.pow(3, s.length()-i-1);
}
return n;
}

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

int result = change("1211");
System.out.println(result);
}

}

package Exam;

public class TwoStringBufferTest {

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

StringBuffer sb1 = new StringBuffer("A");
StringBuffer sb2 = new StringBuffer("B");

method(sb1, sb2);

System.out.println(sb1);
System.out.println(sb2);
}

public static void method(StringBuffer x, StringBuffer y) {
x.append(y);
y = x;
}
}

package Exam;
/**
* 2013校园招聘迅雷Java笔试题
* 实现删除字符串中指定的字符的算法，尽可能的高效.
*/
public class XunLei {

public String removeChars(String source, String remove) {

int i = 0;
int j = 0;
StringBuffer sb = new StringBuffer(source);

//先找到第一个属于要删除的字符
for(; !isRemoved(remove, source.charAt(i))&&
i < source.length(); j=++i) {
;
}

//找到一个不属于要删除的字符覆盖下一个需要覆盖的字符
for(; i < source.length(); i++) {
if(!isRemoved(remove, source.charAt(i))) {
sb.setCharAt(j++, source.charAt(i));
}
}
//改变StringBuffer的长度
sb.setLength(j);
return sb.toString();
}
private boolean isRemoved(String remove, char ch) {
for(int i = 0; i< remove.length(); i++)
if(ch==remove.charAt(i))
return true;
return false;
}
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
String source = "frome now on, i will study hard every day";
String remove = "true";
String result = new XunLei().removeChars(source, remove);
System.out.println(result);
}

}

一道疑惑了很久的选择题。问程序的输出是什么？

package Exam;

import java.util.Date;

public class YY extends Date {

/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
new YY().yy();
}

public void yy() {
// TODO Auto-generated method stub
System.out.println(this.getClass().getName());
System.out.println(super.getClass().getName()); //为什么
System.out.println(getClass().getSuperclass().getName());
}

}

输出结果是：

Exam.YY

Exam.YY

java.util.Date

现在解析一下：Object的getClass()方法的API，解释是：返回此 Object 的运行时类。返回的
Class 对象是由所表示类的 static synchronized 方法锁定的对象。但是super.getClass()为何返回的还是子类的类型，由于getClass()在Object类中定义成了final，子类不能覆盖该方法。注意：super不是超类的引用，而是表示在子类中调用父类的方法或属性而已。如果想得到父类的名称，应该用如下代码：getClass().getSuperClass().getName();

package Exam;

/**
* 2013任子行校园招聘Java笔试题
* 多线程模拟买票问题
*
*/
public class TicketsSole {

public static void main(String[] args) {

TicketThread ts = new TicketThread();

Thread t1 = new Thread(ts, "线程1：");
Thread t2 = new Thread(ts, "线程2：");
Thread t3 = new Thread(ts, "线程3：");

t1.start();
t2.start();
t3.start();

}

static class TicketThread implements Runnable {

private int tickets = 100;

@Override
public void run() {
for(int i = 0; i < 100; i++)
sale();
}

private synchronized void sale() {
if(tickets > 0) {
try {
Thread.sleep(10);
} catch (InterruptedException e) {
e.printStackTrace();
}

System.out.println(
Thread.currentThread().getName()+
"卖出一张票，剩余" + (--tickets) + "张票");
}
}
}

}