JAVA用于创建所有可能的单词组合

Question

我试图获得用户输入的所有可能的单词组合.如输入的话aa, bb, cc应该给出

aa
bb
cc
aabb
aacc
bbaa
bbcc
ccaa
ccbb
aabbcc
aaccbb
bbaacc
bbccaa
ccbbaa
ccaabb

它们可以按任何顺序排列,但最好是按顺序排列.

我一直试图在过去一小时内完成这项工作,我觉得我对一些我无法弄清楚并继续进行的事情感到困惑.有人可以指出我正确的方向.

到目前为止的代码是

import java.util.Arrays;
import java.util.Scanner;

public class WordCombination {
private static String[] wordlist;
private static String[] wordcomb;

public static void main(String[] argv){
    Scanner a = new Scanner(System.in);

    System.out.print("Enter Words:");
    setWords(a.nextLine());

    creatCombinations();

}

private static void setWords(String words){
    System.out.println("Entered words: " + words);
    wordlist = words.split("\\s+");
    Arrays.sort(wordlist);
    System.out.println(Arrays.toString(wordlist));
}

private static void creatCombinations(){
    int size = wordlist.length;
    int perm = (int) Math.pow(size, size);
    int c = 1;

    wordcomb = new String[perm];

    String word = "";
    /*
    for(int i = 0; i < size; i++){
        word = wordlist[i];         
        for(int j = 0; j < size; j++){
            word += wordlist[j];            
            System.out.println(c + ": " + word + ".com");
            c++;
        }
        word = "";
    }*/
    int l = 0;
    for(int i = 0; i < size; i++){
        int permj = (i+1) * size;
        System.out.println("------------------> " + permj + " permutations for " + (i + 1) + " words combination");
        int iterations = permj * (i+1);
        System.out.println(" Iterations: " + iterations);
        word = wordlist[i];
        for(int j = 0; j < permj; j++){
            for(int k = 0; k < i+1; k++){
                int permi = i * size;
                int index = permi + (k%permj);
                wordcomb[c-1] += "" + wordlist[l%size];
                out(l%size + "");
                l++;
            }
            System.out.println(c + ": " + wordcomb[c-1]);
            c++;
        }
        word = "";
    }

}

private static void out(String s){
    System.out.println(s);
}

}

*编辑:我得到的输出是*

    Enter Words:1 2 3
Entered words: 1 2 3
[1, 2, 3]
------------------> 3 permutations for 1 words combination
 Iterations: 3
0
1: 1
1
2: 2
2
3: 3
------------------> 6 permutations for 2 words combination
 Iterations: 12

Enter Words:aa bb cc
Entered words: aa bb cc
[aa, bb, cc]
------------------> 3 permutations for 1 words combination
 Iterations: 3
0
1: aa
1
2: bb
2
3: cc
------------------> 6 permutations for 2 words combination
 Iterations: 12
0
1
4: aabb
2
0
5: ccaa
1
2
6: bbcc
0
1
7: aabb
2
0
8: ccaa
1
2
9: bbcc
------------------> 9 permutations for 3 words combination
 Iterations: 27
0
1
2
10: aabbcc
0
1
2
11: aabbcc
0
1
2
12: aabbcc
0
1
2
13: aabbcc
0
1
2
14: aabbcc
0
1
2
15: aabbcc
0
1
2
16: aabbcc
0
1
2
17: aabbcc
0
1
2
18: aabbcc

Answer 1

一个问题是wordcomb[c-1]从开始null,而不是空字符串.当您添加到它时,null转换为"null",其余的添加到它.

所以你需要初始化wordcomb[c-1]为一个空字符串:

for(int j = 0; j < permj; j++){
    wordcomb[c-1] = ""; // <--------------------------
    for(int k = 0; k < i+1; k++){
        int permi = i * size;
        int index = permi + (k%permj);
        wordcomb[c-1] += "" + wordlist[l%size];
        out(l%size + "");
        l++;
    }
    System.out.println(c + ": " + wordcomb[c-1]);
    c++;
}