河南理工大學(xué)Java基礎(chǔ)入門(mén)課后代碼

1、/第二章：1.編寫(xiě)程序，實(shí)現(xiàn)計(jì)算“1+3+5+.+99”的值public class Add public static void main(String args)int sum=0;for(int i=1;i<100;i+ )if(i%2!=0)sum+=i;System.out.print(sum);/第二章 2返回y值public class ReturnY public static void main(String args)int y=function(3);System.out.print(y); public static int function(int x) int

2、 y; if(x>0) y=x+3; else if(x=0) y=0; else y=x*x-1; return y; /第二章 3編寫(xiě)程序，冒泡法排序public class MaoPao public static void main(String args) int arr=25,24,12,76,101,96,28;for(int i=0;i<arr.length-1;i+)/定義內(nèi)層循環(huán)for(int j=0;j<arr.length-i-1;j+)if(arrj>arrj+1)/比較相鄰元素/ 下面三行代碼用來(lái)交換兩個(gè)元素int temp=arrj;arr

3、j=arrj+1;arrj+1=temp;for(int i=0;i<arr.length;i+)System.out.println(arri+"");/ 第三章 1.設(shè)計(jì)學(xué)生類(lèi)Student，并進(jìn)行測(cè)試class Studentprivate String name;private double grade;public Student()public Student (String name,double grade)=name;this.grade=grade;public String getName()return name;public

4、 void setName(String name)=name;public double getGrade()return grade;public void setGrade(double grade)this.grade=grade;public class Test public static void main(String args) Student s=new Student();s.setName("zhangsan");s.setGrade(90);Student s1=new Student("lisi",100);

5、/第三章2.定義一個(gè)Father和Child類(lèi),并進(jìn)行測(cè)試class Fatherprivate String name="zhangjun"class Childpublic void introFather()System.out.println("My Fathers name"+name);public class Test0 public static void main(String args)Father.Child child=new Father().new Child();roFather();/第四章1設(shè)計(jì)一個(gè)學(xué)生

6、類(lèi)Students和它的一個(gè)子類(lèi)Undergraduateclass Studentspublic String name;public int age;public Students(String name,int age)=name;this.age=age;public void show()System.out.println("name:"+name+"age:"+age);class UnderGraduate extends Studentspublic String degree;public UnderGraduate

7、(String name,int age,String degree)super(name,age);this.degree=degree;public void show()System.out.println("name:"+name+"age:"+age+"degree:"+degree);public class Test1 public static void main(String args)Students student=new Students("zhangsan",16);student.sho

8、w();UnderGraduate underGraduate=new UnderGraduate("lisi",20,"bechalor");underGraduate.show();/第四章2設(shè)計(jì)一個(gè)Shap接口和它的兩個(gè)實(shí)現(xiàn)類(lèi)Square和Circleinterface Shapedouble area(double givenValue);class Square implements Shapepublic double area(double sideLength)return sideLength*sideLength;class Circ

9、le implements Shapepublic double area(double r)return Math.PI*r*r;public class test2 public static void main(String args) Shape square=new Square();Shape circle=new Circle();System.out.println(square.area(2);System.out.println(circle.area(3);/第四章3自定義一個(gè)異常類(lèi)NoThisSoundException和Player類(lèi)，在Player的play（）方法

10、中使用自定義異常class NoThisSoundException extends Exceptionpublic NoThisSoundException()super();public NoThisSoundException(String message)super(message);class Playerpublic void play(int index) throws NoThisSoundExceptionif(index>10)throw new NoThisSoundException("你播放的歌曲不存在");System.out.print(

11、"正在播放歌曲");public class Test3 public static void main(String args)Player player=new Player();tryplayer.play(13);catch (NoThisSoundException e)System.out.print("異常信息為："+e.getMessage();第五章5簡(jiǎn)答題1、一種是繼承java.lang包下的Thread類(lèi)，覆寫(xiě)Thread類(lèi)的run()方法，在run()方法中實(shí)現(xiàn)運(yùn)行在線(xiàn)程上的代碼。new Thread() public void

12、run().start();另一種就是實(shí)現(xiàn)java.lang.Runnable接口，同樣是在run()方法中實(shí)現(xiàn)運(yùn)行在線(xiàn)程上的代碼。new Thread(new Runnable() public void run().start() 2、調(diào)用sleep()方法，正在執(zhí)行的線(xiàn)程主動(dòng)讓出CPU去執(zhí)行其他線(xiàn)程，在sleep()方法指定的時(shí)間過(guò)后，CPU才會(huì)回到這個(gè)線(xiàn)程上繼續(xù)往下執(zhí)行，如果當(dāng)前線(xiàn)程進(jìn)入了同步鎖，sleep()方法并不會(huì)釋放鎖，即使當(dāng)前線(xiàn)程使用sleep()方法讓出了CPU，但其它被同步鎖擋住了的線(xiàn)程也無(wú)法得到執(zhí)行。wait()在一個(gè)已經(jīng)進(jìn)入了同步鎖的線(xiàn)程內(nèi)進(jìn)行調(diào)用，讓當(dāng)前線(xiàn)程暫時(shí)讓出

13、同步鎖，以便其它正在等待此鎖的線(xiàn)程可以得到同步鎖并運(yùn)行。當(dāng)其它線(xiàn)程調(diào)用了notify()方法后，調(diào)用wait()方法的線(xiàn)程就會(huì)解除wait狀態(tài)，當(dāng)再次獲得同步鎖后，程序可以繼續(xù)向下執(zhí)行。/通過(guò)繼承Thread類(lèi)方式創(chuàng)建兩個(gè)線(xiàn)程，在Thread構(gòu)造方法中指定線(xiàn)程的名稱(chēng)并打印出來(lái)public class MyThread extends Thread public MyThread (String name)super(name);public void run()System.out.println(this.getName();public static void main(String ar

14、gs)new MyThread("Thread1").start();new MyThread("Thread2").start();/通過(guò)實(shí)現(xiàn)Runnable接口的方式創(chuàng)建一個(gè)新的線(xiàn)程，要求main線(xiàn)程打印100次“main”，新線(xiàn)程打印50次“new”public class MyRunnable implements Runnable public void run()for(int i=0;i<50;i+)System.out.println("new");public static void main(String a

15、rgs) new Thread(new MyRunnable().start();for (int i=0;i<100;i+)System.out.println("main");/模擬三個(gè)老師同時(shí)分發(fā)80份學(xué)習(xí)筆記，每個(gè)老師相當(dāng)于一個(gè)線(xiàn)程class Teacher implements Runnableprivate int notes=80;public void run()while(true)dispatchNotes();/調(diào)用售票方法if(notes<=0)break;private synchronized void dispatchNotes()

16、if(notes>0)tryThread.sleep(10);/經(jīng)過(guò)的線(xiàn)程休眠10scatch(InterruptedException e)e.printStackTrace();System.out.println(Thread.currentThread().getName()+"-發(fā)出的筆記"+notes+"-");public class Test4 public static void main(String args) Teacher t=new Teacher();new Thread(t,"陳老師").star

17、t();new Thread(t,"高老師").start(); new Thread(t,"李老師").start();/第五章4.編寫(xiě)10個(gè)線(xiàn)程，第一個(gè)從1加到10，第二個(gè)從11加到20.第十個(gè)線(xiàn)程從91加到100，最后把10個(gè)線(xiàn)程結(jié)果相加public class Accumulator extends Thread private int startNum;public static int sum;public Accumulator(int startNum)this.startNum=startNum; public static synch

18、ronized void add(int num)sum+=num;public void run()int sum=0;for(int i=0;i<10;i+)sum+=startNum+i;add(sum);public static void main(String args) throws ExceptionThread threadlist= new Thread10;for(int i=0;i<10;i+)threadlisti= new Accumulator(10*i+1);threadlisti.start();for(int i=0;i<10;i+)threadlisti.join();System.out.println("sum is:"+sum);/第六章1.編寫(xiě)程序，實(shí)現(xiàn)字符串大小寫(xiě)的轉(zhuǎn)換并倒序輸出public class Test public static void