Question

我有十个带有单词的数组列表。我想创建另一个包含2个字段的数组列表，word，int =发生了多少个数组列表。

ArrayList<String> text1;
ArrayList<String> text2;
ArrayList<String> text3;
ArrayList<String> text4;
ArrayList<String> text5;
ArrayList<String> text6;
ArrayList<String> text7;
ArrayList<String> text8;
ArrayList<String> text9;
ArrayList<String> text10;

我想要像

这样的结果

apple 3
banana 8
cucumber 5
...

Answer 1

如果您使用的是Java8，则可以使用Collectors#groupingBy()收集器：

Map<String, Long> result = 
            Stream.of(text1, text2, text3 .... text10)
                  .flatMap(list -> list.stream())
                  .collect(Collectors.groupingBy(x -> x, Collectors.counting()));

如果您运行的是Java8之前的版本，则需要遍历每个列表并将每个元素添加到Map<String, Integer>。操作其中一个列表的简短示例：

Map<String, Integer> result = new TreeMap<String, Integer>();
for (String x : text1) {
   if (!result.containsKey(x)) {
       result.put(x, 1);
   } else {
       Integer count = result.get(x);
       result.put(x, ++count);
   }
}

Answer 2

//将数组放入向量中并使用其索引遍历ArrayLists并计算单词的出现次数。像这样：

import java.util.Vector;
import java.util.ArrayList;

public class WordCount{

    private static Vector<ArrayList<String>> stringArrays = new Vector<ArrayList<String>>();

    public static void main(String[] args){

        ArrayList<String> text1 = new ArrayList<String>();
        ArrayList<String> text2 = new ArrayList<String>();
        ArrayList<String> text3 = new ArrayList<String>();
        ArrayList<String> text4 = new ArrayList<String>();
        ArrayList<String> text5 = new ArrayList<String>();
        ArrayList<String> text6 = new ArrayList<String>();
        ArrayList<String> text7 = new ArrayList<String>();
        ArrayList<String> text8 = new ArrayList<String>();
        ArrayList<String> text9 = new ArrayList<String>();
        ArrayList<String> text10 = new ArrayList<String>();

        stringArrays.add(text1);
        stringArrays.add(text2);
        stringArrays.add(text3);
        stringArrays.add(text4);
        stringArrays.add(text5);
        stringArrays.add(text6);
        stringArrays.add(text7);
        stringArrays.add(text8);
        stringArrays.add(text9);
        stringArrays.add(text10);

        stringArrays.get(0).add("apple");
        stringArrays.get(0).add("cucumber");
        stringArrays.get(1).add("apple");
        stringArrays.get(1).add("cucumber");
        stringArrays.get(2).add("apple");
        stringArrays.get(2).add("banana");
        stringArrays.get(2).add("cucumber");
        stringArrays.get(3).add("banana");
        stringArrays.get(4).add("banana");
        stringArrays.get(5).add("banana");
        stringArrays.get(6).add("banana");
        stringArrays.get(7).add("banana");
        stringArrays.get(7).add("cucumber");
        stringArrays.get(8).add("banana");
        stringArrays.get(9).add("banana");
        stringArrays.get(9).add("cucumber");

        System.out.println("apple " + countWord("apple"));
        System.out.println("banana " + countWord("banana"));
        System.out.println("cucumber " + countWord("cucumber"));
    }//end main

    //  Count the words
    private static int countWord(String findWord){          
        boolean wordFound;
        int wordCount = 0;
        for( int i = 0; i < stringArrays.size(); ++i ){
            wordFound = false;
            for ( int j = 0; j < stringArrays.get(i).size() && !wordFound; ++j ){
                if ( stringArrays.get(i).get(j).equals(findWord) ) wordFound = true;
            }if( wordFound ) ++wordCount;
        }
        return wordCount;
    }
}//end WordCount class

Answer 3

创建一个循环/迭代器，然后将其放入循环中并使用您的过程

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

    int numberOfOccurrence = 0;
    String yourWord = "";

    for(){

        //Process your list and extract out the word and the number of occurrence the put it on your Map.
       //this is the key, and this is the value.
        map.put(yourWord, numberOfOccurrence);
    }

你的单词作为一个键，并将出现的数量作为一个值。

Answer 4

使用Map<String, Integer>键作为条目名称，使用值作为计数。

Map<String, Integer> bucket = new HashMap<String, Integer>();
//you can aggregrate (join) all list as a single list here
for (String entry : lists) {        //need to iterate all of your lists
    int count = 1;
        if (bucket.containsKey(entry)) {
            count = bucket.get(entry) + 1;
        }
        bucket.put(entry, count);
}
//here bucket is fulfilled with entry name & count

计算arraylist中的出现次数并创建另一个arraylist

4 个答案: