【TIJ4】第四章全部习题

分类: IT文章 • 2024-08-10 19:27:32

第四章没啥好说的......

4.1

 1 package ex0401;
 2 //[4.1]写一个程序打印从1到100的值
 3 
 4 public class PrintOneToHundred 
 5 {
 6     public static void main(String[] args)
 7     {
 8         for(int i = 1; i <= 100; ++i)
 9             System.out.print(i + " ");
10     }
11 }

4.1

4.2-4.3

 1 package ex040203;
 2 //[4.2]写一个程序,产生25个int类型的随机数.对于每一个随机值,使用if-else语句来讲其分类为大于小于,或等于紧随它产生的值
 3 //[4.3]修改练习2,把代码用一个while无限循环包括起来.然后运行它直至键盘中断其运行(通常是通过按Ctrl+C).
 4 
 5 import java.util.Random;
 6 
 7 public class GetRandomInteger 
 8 {
 9     public static void main(String[] args)
10     {
11         int i = 0;
12         Random rand = new Random();
13         int curr = rand.nextInt();
14         int prev = 0;
15         //[4.2]
16         while(++i < 25)
17         //[4.3]
18         //while(true)
19         {
20             prev = rand.nextInt();
21             System.out.print(curr + " ");
22             if(curr > prev)
23                 System.out.print("greater than ");
24             else if(curr < prev)
25                 System.out.print("less than ");
26             else
27                 System.out.print("equals ");
28             curr = prev;
29         }
30         System.out.print(prev);
31     }
32 }

4.2-4.3

4.4

 1 package ex0404;
 2 //[4.4]写一个程序,使用两个嵌套的for循环和取余操作符来探测和打印素数
 3 
 4 public class GetPrime 
 5 {
 6     public static void main(String[] args)
 7     {
 8         System.out.println(2);
 9         for(int number = 3; number < 10000; number += 2)
10         {
11             int index;
12             for(index = 3; index < number ; index += 2)
13             {
14                 if(number % index == 0)
15                     break;
16             }
17             if(index * index > number)
18                 System.out.println(number);
19         }
20     }
21 }

4.4

4.5

 1 package ex0405;
 2 //重复练习[3.10],不要用Integer.toBinaryString()方法,而是用三元操作符合按位操作符来显示二进制的1和0
 3 
 4 public class AnotherBitOperation 
 5 {
 6     public static void main(String[] args)
 7     {
 8         int first = 0x2AA;
 9         int second =0x133;
10         
11         for(int i = 0; ((first >> i) & 0xFFFF) != 0; ++i)
12             System.out.print((first >> i ) & 1);
13         System.out.println("");
14         for(int i = 0; ((second >> i) & 0xFFFF) != 0; ++i)
15             System.out.print((second >> i ) & 1);
16         System.out.println("");
17         for(int i = 0; (((first & second) >> i) & 0xFFFF) != 0; ++i)
18             System.out.print(((first & second) >> i ) & 1);
19         System.out.println("");
20         for(int i = 0; (((first | second) >> i) & 0xFFFF) != 0; ++i)
21             System.out.print(((first | second) >> i ) & 1);
22         System.out.println("");
23         for(int i = 0; (((first ^ second) >> i) & 0xFFFF) != 0; ++i)
24             System.out.print(((first ^ second) >> i ) & 1);
25         System.out.println("");
26     }
27 }

4.5

4.7

 1 package ex0407;
 2 //[4.7]修改本章练习1,通过使用break关键词,使得程序在打印到99时退出.然后尝试用return达到相同目的
 3 
 4 public class TestBreakAndReturn 
 5 {
 6     public static void main(String[] args)
 7     {
 8         for(int i = 1; i <= 100; ++i)
 9         {
10             if(i == 100)
11                 return;
12                 //break;
13             System.out.print(i + " ");
14         }
15     }
16 }

4.7

4.8

 1 package ex0408;
 2 //[4.8]写一个switch开关语句,为每个case打印一个消息.然后把这个switch放进for循环来测试每个case.
 3 //先让每个case后面都有break,测试一下会怎么样;然后把break删除,看看会怎样.
 4 
 5 public class TestSwitch 
 6 {
 7     public static void main(String[] args)
 8     {
 9         for(int i = 0; i < 3; ++i)
10         {
11             switch(i)
12             {
13             case 0:
14                 System.out.println("Cat");//break;
15             case 1:
16                 System.out.println("Dog");//break;
17             case 2:
18                 System.out.println("Bird");//break;
19             default:
20                 break;
21             }
22         }
23     }
24 }

4.8

4.9

 1 package ex0409;
 2 //[4.9]一个斐波那契数列是由数字从第三个数字其都是前两个数字的和.
 3 //创建一个方法,接收一个整数参数,并显示从第一个元素开始,总共有该参数指定的个数所构成的所有斐波那契数字.
 4 
 5 class Fibonacci
 6 {
 7     private static final int FIRST = 1;
 8     private static final int SECOND = 1;
 9 
10     public static void printFibonacci(int length)
11     {
12         if(length <= 0)
13             System.out.println("error!");
14         switch(length)
15         {
16         case 2:
17             System.out.println(FIRST);
18         case 1:
19             System.out.println(SECOND);break;
20         default:
21         {
22             int prevprev = FIRST;
23             int prev = SECOND;
24             int curr;
25             System.out.println(FIRST);
26             System.out.println(SECOND);
27             for(int i = 3; i <= length; ++i)
28             {
29                 curr = prevprev + prev;
30                 System.out.println(curr);
31                 prevprev = prev;
32                 prev = curr;
33             }
34         }
35         }
36     }
37 }
38 public class ShowFibonacci 
39 {
40     public static void main(String[] args)
41     {
42         Fibonacci.printFibonacci(10);
43     }
44 }

4.9

【TIJ4】第四章全部习题

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