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  • 二、编程题

    1 将数组 int [] a={9,5,7,8,1,3,2,6,4} 进行冒泡排序

    Public class test {

    Public static void main(String[] args){

          int [] a={9,5,7,8,1,3,2,6,4};

          for(int i=1;i<a.length;i++){

              for(int j=0;j<a.length-i;j++){

                 if(a[j]<a[j+1]){

                   int temp=a[j];

                   a[j]=a[j+1];

                   a[j+1]=temp;

    }

    }

    2 写出单例设计模式

    Public class Singleton{

       Private Singleton(){}

       Private static Singleton instance=null;

       Public static Singleton getInstance(){

          If(instance==null){

            Instance=new Singleton();

    }

          return instance;

    }

    }

    3 键盘输入十行数据,直到输入quit就退出程序,将输入的数据保存在D: empinfo.txt中,该文件不存在就创建该文件。

    Public class Test{

        static String path=” D:\temp\info.txt”;

    Public static void main(String[] args){

       File f=new File(path);

       If( ! f.exists()  ){

           f.createNewFile();

    }

       BufferedReader br=new BufferedReader(New InputStreamReader(System.in)); 

      BufferedWriter bw=new BufferedWriter(new FileWriter(f));

       String line=null;

       While((line=br.readLine())!=null &&!(line.equals(“quit”))){

           bw.write(line);

           bw.newLine();

           bw.flush();

    }

       br.close();

       bw.close();

    }

    }

    4 模拟生成1个班级,该班级有9个学生对象,用集合模拟下列操作。

      A.班级再增加一位学生

      B.将学号是S001的姓名修改为”张恒”

      C.统计所有学生的平均分

      D.将学生的所有信息保存到文件student.txt中

    }

    for(int k:a){

      system.out.print(k+”   ”);

    }

    Public class Student{

       Private String sno;

       Private String name;

       Private int score;

       Public String toSTring(){

      Return “Student [sno=”+sno+”, name=”+name+”, score=”+score+”]”;

    }

       Public Student(String sno,String name,int score){

           This.sno=sno;

           This.name=name;

           This.score=score;

    }

    Public void setScore(int score){

        This.score=score;

    }

    Public int getScore(){

    Return score;

    }

    Public void setSno(String sno){

        This.sno=sno;

    }

    Public String getSno(){

        Return sno;

    }

    Public void setName(String name){

       This.name=name;

    }

       Public String getName(){

           Return name;

    }

       Public static void main(String[] args){

          List<Student> class="new" ArrayList<Student>();

          Student students={

    New Student(“s001”,”张1”,65);

    New Student(“s001”,”张2”,66);

    New Student(“s001”,”张3”,67);

    New Student(“s001”,”张4”,68);

    New Student(“s001”,”张5”,44);

    New Student(“s001”,”张6”,55);

    New Student(“s001”,”张7”,66);

    };

          For(Student student :students){

                Class.add(student);

    }

           Class.add(new Student(“s008”,”张8”,88));

           For(Student student :students){

                If(student.sno.equals(“s001”)){

                     Student.setName(“张恒”);

                     Break;

    }

    }

           Int total=0,i=0;

           For(Student student :students){

              Total+=student.getsScore();

    i++;           

    }

           System.out.print(“平均分”+total/i);

    File f=new File(“f: \student.txt”);

    File f=new File(path);

       If( ! f.exists()  ){

           f.createNewFile();

    }

    BufferedWriter bw=new BufferedWriter(new FileWriter(f,true));

           For(Student student :students){

          

               Bw.write(student.toString());

                

    }

         Bw.close();

    }

    }

    5 模拟四个线程对同一个数据I进行操作

        1号和3号线程做加一

        2号和4号线程做减一

    }

    Public class Date{

       Static int index=0;

    Public synchronized void  add(){

        Index++;

    }

    Public synchronized void sub(){

        Index--;

    }

    }

    Public class A  implements Runnable{

        Date date;

    Public A(Date date){

       This.date=date;

    }

    Public void run(){

       For(int  i=0;i<20;i++){

             date.add();

            Thread.sleep(20);

    }

    }

    }

    Public class B  implements Runnable{

        Date date;

     Public B(Date date){

       This.date=date;

    }

        

    Public void run(){

       For(int  i=0;i<20;i++){

             date.sub();

            Thread.sleep(30);

    }

    }

    }

    Public class Test{

         Public static void main(String[] args){

           Date date =new Date();

            A a=new A(date);

            B b=new B(date);

            Thread t1=new Thread(a,”1号”);

            Thread t3=new Thread(a,”3号”);

            Thread t1=new Thread(b,”2号”);

            Thread t1=new Thread(b,”4号”);

            t1.start();

            t2.start();

            t3.start();

            t4.start();

            

    }

    }

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  • 原文地址:https://www.cnblogs.com/future-zmy/p/6407335.html
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