如何將字符串數組列表的哈希碼存儲在數組列表中

Question

我需要幫助將字符串數組列表「hashNumberStrg」的哈希碼存儲在另一個數組列表中。我的導師希望我們生成100萬個隨機整數，將它們轉換爲字符串，然後獲取每個字符串的哈希碼。有人可以幫助我生成哈希碼並將它們存儲到鏈接列表中嗎？以下是我迄今爲止：

import java.util.*; 

public class dataStuctures 
{ 

    public static void main(String[] args) 
    { 
    int MAXIMUM = 5;//initializing the maximum integer 
    int MINIMUM = 1;//initializing the minimum integer 

    Random randomGenerator = new Random();//initializing the generation of random integers 

    int range = MAXIMUM - MINIMUM + 1;//setting the range of integers from 1 to 1,000,000 

    ArrayList<Integer> randomNumbers = new ArrayList<Integer>(5);//initializing an ArrayList to store the generated random integers with the capacity of 1,000,000 

    //ArrayList<String> randomNumbersStrg = new ArrayList<String>();//initializing an ArrayList to store store the generated hashcodes into a string 

    for (int index = 1; index <= 5; ++index)//for loop to generate 1,000,000 random integers in a range from 1 to 1,000,000 
    { 
      int randomInt = randomGenerator.nextInt(range) + MINIMUM; 

      randomNumbers.add(randomInt);//storing randomly generated numbers in a vector 


    }//end of for loop for random number generation and storage in an ArrayList 

    System.out.println("random numbers= " + randomNumbers); 
    System.out.println("ArrayList size: " + randomNumbers.size()); 



    ArrayList<String> randomNumbersStrg = new ArrayList<String>(randomNumbers.size()); 
    ArrayList<String> randomNumbersHashCodes = new ArrayList<String>(randomNumbers.size()); 
    for (Integer myInt : randomNumbers) 
    { 
     randomNumbersStrg.add(String.valueOf(myInt)); 
     randomNumbersHashCodes.add(randomNumbersStrg.get(myInt)); 
    } 




    // to test to make sure the integers converted 
    String first = randomNumbersStrg.get(0); 
    System.out.println("hash codeest = " + first.hashCode()); 
    String second = randomNumbersStrg.get(1); 
    String third = randomNumbersStrg.get(2); 
    String fourth = randomNumbersStrg.get(3); 
    String fifth = randomNumbersStrg.get(4); 
    System.out.println("\nfirst = " + first); 
    System.out.println("second = " + second); 
    System.out.println("third = " + third); 
    System.out.println("fourth = " + fourth); 
    System.out.println("fifth = " + fifth); 


    List<String> linkedList = new LinkedList<String>();//initializing Linked List 
    linkedList.addAll(randomNumbersStrg);//adding generated hashcodes to Linked List 







    }//end of main method 

    private static long[] randomNumbers(int index2) 
    { 
    // TODO Auto-generated method stub 
    return null; 
    } 
} 

Answer 1

只需使用一個LinkedList存儲哈希碼和ArrayList存儲搜索次數：

List<Integer> hashCodes = new LinkedList<>(); 
for (int index = 0; index < 1_000_000; ++index) { 
    int randomInt = randomGenerator.nextInt(range) + MINIMUM; 
    hashCodes.add(String.valueOf(randomInt).hashCode()); 
} 

這將做它的散列碼。

然後遍歷hashCodes列表來搜索每一個元素，計算需要多長時間：

List<Long> durations = new ArrayList<>(hashCodes.size()); 
for (int n : hashCodes) { 
    long start = System.nanoTime(); 
    hashCodes.contains(n); // true 
    long end = System.nanoTime(); 
    durations.add(end - start); 
} 

這應該這樣做。然後你有durations列表來計算average和std dev。祝你好運！