Question

当我使用下面的代码遍历我的hashmap列表时，我得到了键和值

    System.out.println( "   (" + key + "," + value + ")" )

但我希望我的值以

的形式返回

关键1：价值1

关键1：价值2

关键2：价值1

关键2：价值2 ......等等。有人可以帮助我。

    public static void main(String[] args)  {
    Map<String, List<String>> conceptMap = new HashMap<String, List<String>>();
    Map<String, List<String>> PropertyMap = new HashMap<String, List<String>>();
    try{
    Scanner scanner = new Scanner(new   FileReader("C:/"));

        while (scanner.hasNextLine()){
        String nextLine = scanner.nextLine();
        String [] column = nextLine.split(":");
        if (column[0].equals ("Property")){
        if (column.length == 4) {
        PropertyMap.put(column [1], Arrays.asList(column[2], column[3]));   
            }
        else {
        conceptMap.put (column [1], Arrays.asList (column[2], column[3]));
            }
        }
        }
        Set<Entry<String, List<String>>> entries =PropertyMap.entrySet();
          Iterator<Entry<String, List<String>>> entryIter = entries.iterator();
          System.out.println("The map contains the following associations:");
          while (entryIter.hasNext()) {
             Map.Entry entry = (Map.Entry)entryIter.next();
             Object key = entry.getKey();  // Get the key from the entry.
             Object value = entry.getValue();  // Get the value.
             System.out.println( "   (" + key + "," + value + ")" );
          }
        scanner.close();

        }   

        catch (Exception e) {
        e.printStackTrace();
        }

Answer 1

替换它：

 System.out.println( "   (" + key + "," + value + ")" );

与

for (Object listItem : (List)value) {
    System.out.println(key + ":" + listItem);
}

Answer 2

使用LinkedHashMap，地图中put个条目的顺序与迭代它们的顺序相同。

Answer 3

while (entryIter.hasNext()) {

      //...
      String key = entry.getKey();  // Get the key from the entry.
      List<String> value = entry.getValue();  // Get the value.

      for(int i = 0; i < value.size(); i++) {
          System.out.println( "   (" + key + "," + value.get(i) + ")" );
      }
}

Answer 4

所以你想打印列表中的值？替换：

Object value = entry.getValue();  // Get the value.
System.out.println( "   (" + key + "," + value + ")" );

有了这个：

List<String> value = entry.getValue();
for(String s : value) {
    System.out.println(key + ": " + s);
}

返回值列表形成迭代

4 个答案: