Java: 将按字符串长度排序的字符串数组拆分为按字符串长度排序的多个数组

Question

我目前有一个按字符串长度排序的字符串数组，例如：

String[] array = [a,b,c,ab,cd,abc,abcde,fghij,klmno]

如何根据字符串大小将此数组转换为多个数组，同时跟踪每个数组的字符串大小？我想要的是：

String[] array1 = [a,b,c]
String[] array2 = [ab,cd]
String[] array3 = [abc]
String[] array5 = [abcde,fghij,klmno]

我可能正在考虑为此使用矩阵，但不知道如何去做。

Answer 1

最好创建一个 Map<Integer, List<String>>，其中键是字符串的长度，值是类似大小的字符串的列表。

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class SimpleArray {

    public static void main(String[] args) {
        String[] array = new String[]{"a","b","c","ab","cd","abc","abcde","fghij","klmno"};

        Map<Integer, List<String>> map = new HashMap<>();

        for (int i = 0; i < array.length; i++) {
            List< String> temp = map.getOrDefault(array[i].length(),new ArrayList<>());
            temp.add(array[i]);
            map.put(array[i].length(),temp);
        }
        System.out.println(map);

    }
}

Answer 2

为了快速访问，您还可以使用列表列表。

String[] array = new String[]{"a","b","c","ab","cd","abc","abcde","fghij","klmno"};
List<List<String>> lists = new LinkedList<>();

// you will have to update this number based on the maximum length of string you are expecting
for (int i = 0; i < 6; i++) {
    lists.add(new LinkedList<>());
}

for (String a: array) {
    lists.get(a.length()).add(a);
}

System.out.println(lists);

此处，第一个列表用于大小，内部列表用于实际字符串。

注意：这仅适用于较小的字符串。如果您有长度为 1、2、100 的字符串。您可能应该使用 HashMap，因为这种方法会浪费大量内存。

使用Java8：

String[] array = new String[]{"a","b","c","ab","cd","abc","abcde","fghij","klmno"};

List<List<String>> lists = IntStream.range(0, 6).<List<String>>mapToObj(
    i -> new LinkedList<>()).collect(Collectors.toCollection(LinkedList::new));

Arrays.stream(array).forEach(a -> lists.get(a.length()).add(a));

System.out.println(lists);

Answer 3

我的解决方案 与@QuickSilver 的相同，只是不太清楚。既然我来了，我也放了我的，因为我有专门的时间，但我再说一遍，我建议关注他。

代码

public static void main(String[] args) {
        String[] array = {"a", "b", "c", "ab", "cd", "abc", "abcde", "fghij", "klmdfwetdfgdfgdfgdg"};
        HashMap<Integer, List<String>> hashMap = new HashMap<>();
        int strLength = array[0].length();

        for (String s : array) {
            while (true) {
                if (s.length() == strLength) {
                    if (hashMap.get(strLength) != null) {
                        List<String> temp = hashMap.get(strLength);
                        temp.add(s);
                        hashMap.put(strLength, temp);
                    } else {
                        List<String> strings = new LinkedList<>();
                        strings.add(s);
                        hashMap.put(strLength, strings);
                    }
                    break;
                } else
                    strLength = s.length();
            }
        }
        System.out.println(hashMap);
    }

Answer 4

使用System:arraycopy

仅使用数组的解决方案：

import java.util.Arrays;

public class Main {
    public static void main(String[] args) {
        String[][] arraysList = new String[1][];
        String[] array = { "a", "b", "c", "ab", "cd", "abc", "abcde", "fghij", "klmno" };
        int srcPos, row = 0;
        for (int i = 0; i < array.length; i++) {
            srcPos = i;
            while (i < array.length - 1 && array[i].length() == array[i + 1].length()) {
                i++;
            }
            // Create a new array to store the current set of strings of equal length
            String[] subarray = new String[i - srcPos + 1];

            // Copy the current set of strings of equal length from array to subarray[]
            System.arraycopy(array, srcPos, subarray, 0, subarray.length);

            // Assign subarray[] to arraysList[][]
            arraysList[row++] = subarray;

            // Copy arraysList[][] to temp [][], increase size of arraysList[][] and restore
            // arrays from temp [][] to arraysList[][]
            String[][] temp = arraysList;
            arraysList = new String[row + 1][subarray.length];
            for (int j = 0; j < temp.length; j++) {
                arraysList[j] = temp[j];
            }
        }

        // Drop the last row which was created to store a new subarray but there was no
        // more subarrays to store and therefore it is empty.
        arraysList = Arrays.copyOf(arraysList, arraysList.length - 1);

        // Display the subarrays
        for (String[] arr : arraysList) {
            System.out.println(Arrays.toString(arr));
        }
    }
}

输出：

[a, b, c]
[ab, cd]
[abc]
[abcde, fghij, klmno]

使用List和数组的解决方案：

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

public class Main {
    public static void main(String[] args) {
        List<String[]> list = new ArrayList<String[]>();
        String[] array = { "a", "b", "c", "ab", "cd", "abc", "abcde", "fghij", "klmno" };
        int srcPos;
        for (int i = 0; i < array.length; i++) {
            srcPos = i;
            while (i < array.length - 1 && array[i].length() == array[i + 1].length()) {
                i++;
            }
            String[] subarray = new String[i - srcPos + 1];
            System.arraycopy(array, srcPos, subarray, 0, subarray.length);
            list.add(subarray);
        }

        // Display the subarrays
        for (String[] arr : list) {
            System.out.println(Arrays.toString(arr));
        }
    }
}

输出：

[a, b, c]
[ab, cd]
[abc]
[abcde, fghij, klmno]

Answer 5

您可以使用 Map 将字符串长度关联到该长度的字符串子数组：

String[] array = {"a", "b", "c", "ab", "cd", "abc", "abcde", "fghij", "klmno"};

Map<Integer, String[]> map = new HashMap<>();

for(int j=0, i=1; i<=array.length; i++)
{
    if(i == array.length || array[i].length() > array[j].length())
    {
        map.put(array[j].length(), Arrays.copyOfRange(array, j, i)) ;
        j = i;
    }
}

for(Integer len: map.keySet())
    System.out.format("%d : %s%n", len, Arrays.toString(map.get(len)));

输出：

1 : [a, b, c]
2 : [ab, cd]
3 : [abc]
5 : [abcde, fghij, klmno]

Java: 将按字符串长度排序的字符串数组拆分为按字符串长度排序的多个数组

Java: Split array of strings sorted by string length into several arrays by string length

java

arrays

split

matrix

sub-array

代码

使用System:arraycopy