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1、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.prin
2、tln(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;
3、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(
4、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_3public static void main(String args)throws IOExce
5、ptionint 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(Wednesda
6、y); 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; i0) re
7、sult=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_1public static void main( String args ) System
8、.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 resul
9、t=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
10、 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()whil
11、e( 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(
12、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 IOExceptionTestThread t=new TestThread();t.start();new BufferedReader(new InputStreamReader(System.in).readLine(); /等待键盘输入t.stopme(); /调用 stopme 方法结束 t 线程class TestThread extends Threadprivate boolean flag=true;public void stopme() /在此方法中控制循环条件flag=false;public void run() int i=0;while(flag) System.out.println(i+); /如果 flag 为真则一直显示递增整数
