计算java数组中出现的次数[重复]

Question

我已经将代码中的read整数修复为不再是I而是一个单独的变量“index”，并理解为什么我会收到Over Ofbound异常，但我有点厚，不明白如何在添加哨兵值0的同时修复它。

import java.util.Scanner;

public class countNumberOccurrence{
  public static void main(String args[]){

  int[] numbers = new int[100];
  inputArray(numbers);

  }

  public static void inputArray(int[] myList){
    Scanner input = new Scanner(System.in);
      System.out.print("Enter integers from 1-100 (input 0 value to end inputs): ");
      int index = 0;
      for(int i = 1; i < myList.length - 1; i++){
        if(i > 0){
          index = input.nextInt();  
          myList[index-1]++;  
        }

        if(myList[index-1] > 1)
          System.out.println(index + " occurs " + myList[index-1] + " times ");
        else
          System.out.println(index + " occurs " + myList[index-1] + " time ");
      }             

  }

}

Answer 1

检测0的输入并结束应用程序的正确逻辑是：

int nextInt;
while ((nextInt = input.nextInt()) != 0)
{
    // do your logic here
}
// print your output here

这是处理输入的正确方法。

始终使用适当的java.util.collections类，并使用for/each或适当的迭代器进行迭代，就不会出现这些错误。

import java.util.HashMap;
import java.util.Map;
import java.util.Random;
import java.util.concurrent.atomic.AtomicInteger;

public class Q21871053
{
    public static void main(final String[] args)
    {
        final Random rnd = new Random();

        final Map<Integer, AtomicInteger> counter = new HashMap<Integer, AtomicInteger>()
        {
            @Override
            public AtomicInteger get(final Object key)
            {
                if (!super.containsKey(key)) { super.put((Integer) key, new AtomicInteger(rnd.nextInt(100))); }
                return super.get(key);
            }
        };

        final AtomicInteger nextInt = new AtomicInteger(rnd.nextInt(100));
        while (nextInt.get() != 0)
        {
            counter.get(nextInt.get()).incrementAndGet();
            if (counter.size() > 1000) { nextInt.set(0); } // limit the run to 1000 numbers
            else { nextInt.set(rnd.nextInt(100)); }
        }

        for (final Integer i : counter.keySet())
        {
        final AtomicInteger integer = counter.get(i);
        final String format = integer.get() > 1 ? "%d occurs %s times\n" : "%d occurs %s time\n";
        System.out.format(format, i, integer);
        }
    }
}

3 occurs 43 times
98 occurs 16 times
64 occurs 35 times
36 occurs 27 times
37 occurs 19 times
7 occurs 58 times
76 occurs 48 times
77 occurs 40 times
41 occurs 68 times
46 occurs 5 times
13 occurs 100 times
14 occurs 15 times
51 occurs 85 times
17 occurs 40 times
85 occurs 16 times
18 occurs 97 times
25 occurs 10 times
24 occurs 12 times
29 occurs 14 times
91 occurs 2 times

@Override
public void functionToBeRateLimited(@Nonnull final String caller)
{
    // do some stuff every time here
    super.timesCalled.get(caller).incrementAndGet();

    // do some stuff only after a certain time has elapsed since the last time it was done
    if (LIMITER.get(caller).tryAcquire())
    {
        System.out.println(String.format("%s Called Rate Limited Logic up to 2 times a second ( 500 ms )", caller));
    }
}