从文本返回 hashmap 的方法

Question

我正在尝试编写一个采用 InputStream 变量并将 HashMap 返回给 main 的方法。但是我被困在如何返回 HashMap 的变量上。 Java 新手，所以我不知道自己在做什么错。对于返回语句：pairCount 无法解析为变量。提前致谢。

private static Map<String, Integer> getHashMap(InputStream in)
{ 

    if (in != null) 
    {
        // Using a Scanner object to read one word at a time from the input stream.
        @SuppressWarnings("resource")
        Scanner sc = new Scanner(in);   
        String word;
        System.out.println(" - Assignment 1 -s%n%n\n");
        // Continue getting words until we reach the end of input 
        List<String> inputWords = new ArrayList<String>();

        while (sc.hasNext()) 
        {  
            word = sc.next();       
            if (!word.equals(null)) 
            {
                inputWords.add(word);
            }
        }
        Map<String, Integer> pairsCount = new HashMap<>();
        Iterator<String> it = inputWords.iterator();

        String currentWord = null;
        String previousWord = null;

        Integer wordCount = 0;
        while(it.hasNext())
        {
            currentWord = it.next();
            if( previousWord != null ) 
            {
                String key = previousWord.concat( "#" ).concat( currentWord );
            if( pairsCount.containsKey( key ) ) 
            {
              Integer lastCount = pairsCount.get( key );
              pairsCount.put( key, lastCount + 1 );
              wordCount = wordCount + lastCount;
            } 
            else 
            {
              pairsCount.put( key, 1 );
              wordCount =  1;
            }
         }
            previousWord = currentWord;     

     }

    }
    return (pairsCount);

}

Answer 1

这可能是因为变量 pairsCount 超出了它的范围。

您在 if 块内部定义它，但试图在外部返回它。

所以尝试定义 Map pairsCount = new HashMap(); 在 if (in != null) 之前