Learn Java-6 from scratch. Execute operations repeatedly using loops and learn java-6

Learn Java-6 from scratch. Execute operations repeatedly using loops and learn java-6

1. Use the for loop;

2. Use the while loop;

3. Use the do-while loop;

4. Early exit loop (break, continue );

5. Name the loop.

 

Program Nines: display the product of integers 1-and 9

 1 package com.jsample; 2  3 public class Nines { 4     public static void main(String[] args){ 5         for(int dex = 1;dex <= 200; dex++){ 6             int multiple = 9 * dex; 7             System.out.println(multiple + " "); 8         } 9         System.out.println();10     }11 }

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Output:

9

......

1800

 

Program Benchmark: view the number of times the computer calculates the square root in one minute

1 package com. jsample; 2 3 public class Benchmark {// declare Benchmark class 4 public static void main (String [] args) {// start the main () block of the program 5 long startTime = System. currentTimeMillis (); // create the variable startTime, and assign the initial value 6 long endTime = startTime + 60000 to the variable with the current time (millisecond value); // create the endTime variable, exactly one minute before startTime. 7 long index = 0; // create the loop variable index 8 while (true) {// infinite loop. You can only use break to break 9 double x = Math. sqrt (index); // calculates the square root of the index and stores it in the x variable 10 long now = System. currentTimeMillis (); // create the variable now and assign the current time to it 11 if (now> endTime) {// more than one minute, jump out of the loop 12 break; 13} 14 index ++; // auto-increment loop variable 15} 16 System. out. println (index + "loops in one minute. "); // display the number of times the square root is calculated 17} 18}

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Output:

12880432183 loops in one minute.

 

Program Mod13: Find the first 400 divisible by 13

 1 package com.jsample; 2  3 public class Mod13 { 4     public static void main(String[] args){ 5         int index = 0; 6         for(int flag = 1; flag <= 400; index++){ 7             if(index % 13 == 0) { 8                 flag++; 9                 System.out.println(index + " ");10             }11         }12     }13 }

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Output:

0

......

5187