每100万次迭代打印一次消息

Question

我需要编写一个循环，每百万次迭代打印一次消息。我想让它运行10秒（时钟时间）以查看打印了多少条语句。

我想我只是绑住自己在海里，现在虽然...

public class OneInAMillion{ 
    public static void main(String []args){ 
    long startTime = System.currentTimeMillis(); //time at start of execution 
    long endTime = startTime + 10000; //time at end of execution (10000 = 10 seconds) 
    int count = 1; 

    while(System.currentTimeMillis() < endTime) { //run this before 10 seconds is up 
     for (int i = 0; i < count; i++) { 
     if(i % 1000000 == 0) { 
      System.out.println("Iteration: " + count++); //print every millionth iteration 
     } 
     } 
    } 

    System.out.println("Time up!"); //print once loop finishes 
    } 
} 

Answer 1

摆脱你for循环，你if和打印i，而不是计数之前做i++，你应该设置。

public class OneInAMillion{ 
    public static void main(String []args){ 
    long startTime = System.currentTimeMillis(); //time at start of execution 
    long endTime = startTime + 10000; //time at end of execution (10000 = 10 seconds) 
    //int count = 1; 
    int i = 0; 
    while(System.currentTimeMillis() < endTime) { //run this before 10 seconds is up 
     i++; 
     if(i % 1000000 == 0) { 
      System.out.println("Iteration: " + i); //print every millionth iteration 
     } 
    } 

    System.out.println("Time up!"); //print once loop finishes 
    } 
} 

Answer 2

你在循环中有一个循环。想想每个循环的作用 - 第一个循环会持续10秒。另一个将简单地从0开始到1，并且在while循环的下一次迭代中，它将从0到2，然后从0到3等等。由于0％1000000为0，所以它也会在0（很多）时打印。

尝试将它们组合成一个单一循环。这可以通过摆脱while循环的，只具有for循环与while循环的条件，因为这样做：

public static void main(String[] args) { 
    long endTime = System.currentTimeMillis() + 10000; //time at end of execution (10000 = 10 seconds) 
    for (int i = 1; System.currentTimeMillis() < endTime; i++) { 
     if(i % 1000000 == 0) { 
      System.out.println("Iteration: " + i/1000000); //print every millionth iteration 
     } 
     } 
     System.out.println("Time up!"); //print once loop finishes 
    } 

注意count将永远是我/ 1000000，所以我摆脱它。

Answer 3

您的for循环退出条件干扰您的while循环退出条件并阻止您在期望时对其进行评估。摆脱while循环：

public class OneInAMillion{ 
    public static void main(String []args){ 
    long startTime = System.currentTimeMillis(); //time at start of execution 
    long endTime = startTime + 10000; //time at end of execution (10000 = 10 seconds) 
    int count = 1; 

    for (int i = 0; i < count; i++) { 
     if(System.currentTimeMillis() >= endTime) { 
     break; 
     } 

     if(i % 1000000 == 0) { 
     System.out.println("Iteration: " + count++); //print every millionth iteration 
     } 
    } 


    System.out.println("Time up!"); //print once loop finishes 
    } 
}