Question

如何在Java中将“ ArrayList”对象转换为“ String [] []”数组？我需要一个二维String数组，而不是一个简单的Array

我有这个文件

word1 word1.1 word1.2
word2 word2.1 word2.2

我需要每个单词都可以与另一个文件进行比较

我尝试过

public void Scanne(File file) throws Exception {

             Scanner scanner = new Scanner(file);
             ArrayList<String> list = new ArrayList<String>();
             while (scanner.hasNextLine()) {
                    String line = scanner.nextLine();
                    String[] parts = line.split("\t");
                    String part2 = parts[2];
                    String part3 = parts[3];
                    String part4 = parts[4];
                    String part5 = parts[5];
                    String part6 = parts[6];
                    String part7 = parts[7];
                    String part8 = parts[8];
                    String part9 = parts[9];
                    String part10 = parts[10];
                    list.add(line);
                    String resultSet[][]= new String[list.size()][parts.length];
                    for (int i = 0; i<list.size(); i++) {
                    I am stuck here       
                    }
}
'''

Answer 1

尝试此代码可能会对您有所帮助。

   public class ArrayListToStringArray {

    public static void main(String args[]){

        //ArrayList containing string objects
        ArrayList<String> nameList = new ArrayList<String>();
        nameList.add("Max");
        nameList.add("Tom");
        nameList.add("John");

        /*
         * To convert ArrayList containing String elements to String array, use
         * Object[] toArray() method of ArrayList class.
         *
         * Please note that toArray method returns Object array, not String array.
         */

        //First Step: convert ArrayList to an Object array.
        Object[] objNames = nameList.toArray();

        //Second Step: convert Object array to String array

        String[] strNames = Arrays.copyOf(objNames, objNames.length, String[].class);

        System.out.println("ArrayList converted to String array");

        //print elements of String array
        for(int i=0; i < strNames.length; i++){
            System.out.println(strNames[i]);
        }
    }
}

Answer 2

根据OP的评论，要求按单词拆分，其中2d数组的每个单元格将存储一个单词，而每一行将对应一个句子。

List<String> l = new ArrayList<>();
l.add("Hello world");
l.add("StackOverflow is awesome");

String[][] s = new String[l.size()][];

for (int i=0; i<l.size(); i++) {
  String[] words = l.get(i).split(" ");
  s[i] = words;
}

for (int i=0; i<s.length; i++) {
  for (int j=0; j<s[i].length; j++) {
    System.out.print(s[i][j] + " ");
  }
  System.out.println();
}

在Java中将“ ArrayList <String>”转换为“ String [] []”

2 个答案: