Java练习题、编程题.doc

第二章注意问题: main函数是Java应用程序执行的入口。(int)23.7结果为23(int)-45.89f结果为-45+”除字符串相加功能外，还能把非字符串转换成字符串 ，如： “x”+123;的结果是“x123” 。 如果对负数取模，可以把模数负号忽略不记，如：5%-2=1。但被模数是负数就另当别论了1， 三元运算符 class TernaryOp public static void main(String args) int salary,daysPresent = 30; salary = daysPresent = 20 ? 2000 : 3000; System.out.println(您本月薪资为 $+salary); ，编写一个程序，这个程序从键盘上输入2个数，然后求这2个数的和，程序结束。提示：调用System.in.read()；可以读取到一个从键盘上输入字符对应的整数。通过这个程序，你一定能体会到在什么 import java.io.*;public class Ch1 public static void main(String args) throws IOExceptionBufferedReader ke=new BufferedReader(new InputStreamReader(System.in);String x;int p,q,m;System.out.print(请输入第一个数);x=ke.readLine();p=Integer.parseInt(x);System.out.print(请输入第二个数);x=ke.readLine();q=Integer.parseInt(x);m=p+q;System.out.println(两个数的和为:+m); ，数组public class Lo public static void main(String args) int aa=32,55,69;for(int i=0;iy) System.out.println(xy); else System.out.println(x= 90) grade = A; else if (testscore = 80) grade = B; else if (testscore = 70) grade = C; else if (testscore = 60) grade = D; else grade = F; System.out.println(Grade = + grade); ，输入06之间的某一个整数，然后把它转换成星期 输出。(0对应星期日）import java.io.*;public class ex3_3 public static void main(String args)throws IOException int day; BufferedReader in =new BufferedReader( new InputStreamReader(System.in); day=(new Integer(in.readLine().intValue();switch (day) case 0: System.out.println(Sunday); break; case 1: System.out.println(Monday); break;case 2: System.out.println(Tuesday); break; case 3: System.out.println(Wednesday); break; case 4: System.out.println(Thursday); break; case 5: System.out.println(Friday); break; case 6: System.out.println(Saturday); break; default: System.out.println(Day out of range Sunday .Saturday ); break; ，打印九九乘数表public class MultiTable public static void main(String args) for (int i=1; i=9;i+) for (int j=1; j=i;j+) System.out.print( +i+*+j+=+i*j); System.out.println(); ，输入一个整数，输出它所有的因数import java.io.*;public class ex3_7 public static void main(String args) throws IOException int n,k; BufferedReader in =new BufferedReader( new InputStreamReader(System.in); System.out.println(Enter a positive integer: ); n=(new Integer(in.readLine().intValue(); System.out.print(Number +n+ Factors ); for (k=1; k = n; k+) if (n % k = 0) System.out.print(k + ); System.out.println(); ，计算数列1,2,10 的和。public class ex3_4 public static void main(String args) int i=1, sum=0; while(i=10) sum+=i; i+; System.out.println(sum=+sum); ，计算存款收益：假设银行中存款10000元，按11.25%的利率，一年后连本带利将变为11125元。你若将此款继续存入银行，试问多长时间就会连本带利翻一番import java.text.*;public class Examp3_4 public static void main(String args) double original,money,interest; int years = 0; original = money= 10000; interest = 11.25 / 100; System.out.println(year money);while (money 2 * original) years = years + 1; money = money + (interest * money); System.out.println( + years + + new DecimalFormat(0.00).format(money); System.out.println(); System.out.println( 第 + years + 年存款额达到 + new DecimalFormat(0.00).format(money) + 元。); 编写一个程序用选择法对数组a=20,10,50,40,30,70,60,80,90,100进行由大到小的排序。import java.io.*;public class SelectSortpublic static void main(String args)int a=20,10,50,40,30,70,60,80,90,100;int temp;for (int i=0; ia.length-1;i+)for (int j=i+1; ja.length ; j+)if (aiaj) temp=ai;ai=aj;aj=temp;for (int k=0;k0) result=result*i; i=i-1; System.out.println(The factorial of +num+ is +result); System.out.println(new thread ends); 运行结果main thread startsmain thread endsnew thread startedThe factorial of 10 is 3628800new thread ends2，使用Runnable接口实现上述程序功能public class Ex8_1 public static void main( String args ) System.out.println(main thread starts); FactorialThread t=new FactorialThread(10); new Thread(t).start(); System.out.println(new thread started,main thread ends ); class FactorialThread implements Runnable private int num; public FactorialThread( int num ) this.num=num; public void run() int i=num; int result=1; while(i0) result=result*i; i=i-1; System.out.println(The factorial of +num+ is +result); System.out.println(new thread ends); 3，用两个线程模拟存票、售票过程 假定开始售票处并没有票，一个线程往里存票，另外一个线程则往出卖票我们新建一个票类对象，让存票和售票线程都访问它。本例采用两个线程共享同一个数据对象来实现对同一份数据的操作public class Ex8_7 public static void main(String args) Tickets t=new Tickets(10); new Consumer(t).start();new Producer(t).start(); class Tickets int number=0; /票号int size; /总票数boolean available=false; /表示目前是否有票可售public Tickets(int size) /构造函数，传入总票数参数this.size=size; class Producer extends ThreadTickets t=null;public Producer(Tickets t)this.t=t; public void run()while( t.number t.size) System.out.println(Producer puts ticket +(+t.number); t.available=true; class Consumer extends Thread /售票线程Tickets t=null;int i=0;public Consumer(Tickets t) this.t=t; public void run()while(it.size) if(t.available=true & i=t.number) System.out.println(Consumer buys ticket +(+i); if(i=t.number) t.available=false;4，线程不断显示递增整数，按下回车键则停止执行import java.io.*;public class Ex8_12public static void main(String args) throws IOException TestThread t=new TestThread(); t.start(); new BufferedReader(n