Question

所以我有一系列这样的名字：

String[] arrayOfName = {"Elephant", "Deer", "Fish", "Crocodile", "Cat", "Dog", "Bird", "Butterfly", "Chicken", "Ant", "Snake", "Lion", "Horse", "Wolf", "Panda", "Swan", "Lobster"};

我在考虑是否有另一个数组，我想将arrayOfName中的4到10个（它是随机的）随机名称放入我的新数组中。

Answer 1

尝试使用Random类：

import java.util.Random;

public class Test {

    public static void main (String[] args) {

        Random rand = new Random();
        String[] arrayOfName = {"Elephant", "Deer", "Fish", "Crocodile", "Cat", "Dog", "Bird", "Butterfly", "Chicken", "Ant", "Snake", "Lion", "Horse", "Wolf", "Panda", "Swan", "Lobster"};

        // this will give you a random value between 4 (inclusive) and 11 (exclusive, or 10 inclusive)
        int numberOfRandomValues = rand.nextInt(7) + 4;

        String[] newArrayOfName =  new String[numberOfRandomValues];

        for(int  i = 0; i < numberOfRandomValues; i++) {
            // this will give you a random value between 0 (inclusive) and the size of array (inclusive as well) which you can use to add a random element
            int randomPosition = rand.nextInt(arrayOfName.length);
            newArrayOfName[i] = arrayOfName[randomPosition];
            System.out.println(" - Just added " + newArrayOfName[i] + " on position " + i);
        }

    }

}

Answer 2

第一步：您可以使用Random对象并生成4到10之间的数字。

    Random random = new Random();
    int minElementToTake = 4;
    int maxElementsToTake = 10;
    int nbElementToTake = random.nextInt(maxElementsToTake - minElementToTake + 1) + minElementToTake;

此处random.nextInt()生成0到6之间的数字。然后，我们将4添加到其中因此int nbElementToTake为>= 4 && <=10。

第二步：迭代“nbElementToTake”次并使用nextInt（）方法生成介于0和原始数组大小之间的int。通过这种方式，您将拥有一个表示原始数组的随机索引的int，您可以从中检索一个随机元素，以将其存储在目标数组中。

注意：在提出的解决方案中，我添加了一个Set以避免在目标数组中多次添加相同的值。它不是处理这种问题的有效方法，但对于数据量不大的数组，这是可以接受的通过使用List而不是数组，我们可以为此问题提供更高效，更简单的解决方案。

import java.util.Arrays;
import java.util.HashSet;
import java.util.Random;
import java.util.Set;

public class AnimalRandom {

    public static void main(String[] args) {
        String[] arrayOfName = { "Elephant", "Deer", "Fish", "Crocodile", "Cat", "Dog", "Bird", "Butterfly", "Chicken",
                "Ant", "Snake", "Lion", "Horse", "Wolf", "Panda", "Swan", "Lobster" };

        Random random = new Random();
        int minElementToTake = 4;
        int maxElementsToTake = 10;
        int nbElementToTake = random.nextInt(maxElementsToTake - minElementToTake + 1) + minElementToTake;

        String[] newArray = new String[nbElementToTake];

        Set<Integer> indexesUsed = new HashSet<>();
        Random randomOrder = new Random();
        for (int i = 0; i < nbElementToTake; i++) {

            int maxInclusive = arrayOfName.length;

            int indexToUse = randomOrder.nextInt(maxInclusive);

            while (indexesUsed.contains(indexToUse)) {
                indexToUse = randomOrder.nextInt(maxInclusive);
            }
            indexesUsed.add(indexToUse);
            newArray[i] = arrayOfName[indexToUse];
        }

        System.out.println(Arrays.toString(newArray));
    }

}

Answer 3

虽然没有经过测试，但想出了这个要求的存根 -

/**
 * To pick any few sequential input strings from the list of inputs
 * @param inputArr input array of strings
 * @param few number of strings to be picked up
 * @return any random sequence of x strings from input
 */
public static String[] randomSequenceOfFewStrings(String[] inputArr, int few) {
    String[] outputArr = new String[few];
    Random random = new Random();
    int index = random.nextInt(inputArr.length - few);
    for (int i = 0; i < few; i++) {
        outputArr[i] = inputArr[index];
        index++;
    }
    return outputArr;
}

其中您可以将相同的代码用作 -

System.out.println(Arrays.toString(randomSequenceOfFewStrings(arrayOfName, 5)));

注意 - 这应该为每个具有相同参数的调用生成不同的固定数量的元素序列，并为每个不同的方法调用生成不同数量的元素的不同序列。

Answer 4

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Random;

public class Example1 {
    public static void main(String[]args){
        String[] arrayOfName = {"Elephant", "Deer", "Fish", "Crocodile", "Cat", "Dog", "Bird", "Butterfly", "Chicken", "Ant", "Snake", "Lion", "Horse", "Wolf", "Panda", "Swan", "Lobster"};
        List<String> listOfNames = new ArrayList<>(Arrays.asList(arrayOfName));     // convert array to list
        Collections.shuffle(listOfNames);                                           // shuffle the list
        Random ran = new Random();
        List<String> listOfRandomNames = new ArrayList<>(listOfNames.subList(0, 4 + ran.nextInt(6)));   // pick random number of strings from the shuffled list
        String[] arrayOfRandomNames = new String[listOfRandomNames.size()];     // new Array with size of random list
        arrayOfRandomNames = listOfRandomNames.toArray(arrayOfRandomNames);     // convert list to array
        System.out.println(Arrays.toString(arrayOfRandomNames));                // print or do whatever
    }   
}

将数组的随机元素插入到java中具有特定索引的另一个数组中

4 个答案: