java-使用HashMap对JTree节点进行分组

我正在尝试使用HashMap构建JTree,将Values作为主要类别,将Keys作为子类别.本质上,它将看起来像这样：

Movies
   -Marvel
      -The Avengers
      -Guardians of the Galaxy
   -James Bond
      -Casino Royale
      -Skyfall

现在,当我尝试构建树时,我得到了一对一的层次结构,其中为每个键分配了一个新类别,即使已经存在与String匹配的类别.看起来像这样：

Movies
   -Marvel
      -The Avengers
   -Marvel
      -Guardians of the Galaxy

下面是我的代码.如何搜索节点以确保没有重复的类别？

public class JTree extends JFrame {
        private javax.swing.JTree genreTree;
        private JPanel panel1;

public JTree() throws IOException{
    super("Genre Search");
    setContentPane(panel1);
    pack();
    setDefaultCloseOperation(WindowConstants.HIDE_ON_CLOSE);
    setVisible(true);
    setSize(new Dimension(500,500));

    genreTree.setModel(null);

    HashMap<String, String> hash = new HashMap<String, String>();
    hash.put("Avengers","Marvel");
    hash.put("Guardians","Marvel");
    hash.put("Casino Royale","James Bond");
    hash.put("Skyfall","James Bond");

    String genreName = "Movies";
    DefaultMutableTreeNode genreMainTree = new
            DefaultMutableTreeNode(genreName);
    DefaultMutableTreeNode mediaTitleNode = new DefaultMutableTreeNode("");
    DefaultMutableTreeNode universeTitleNode = new
            DefaultMutableTreeNode("");


    Set<String> keys = hash.keySet();
    Collection<String> values = hash.values();

    ArrayList<Map.Entry<String,String>> copy = new
            ArrayList<Map.Entry<String, String>>();
    copy.addAll(hash.entrySet());

    for (Map.Entry<String,String> e : copy){

        mediaTitleNode = new DefaultMutableTreeNode(e.getKey());

        universeTitleNode = new DefaultMutableTreeNode(e.getValue());

        genreMainTree.add(universeTitleNode);

        universeTitleNode.add(mediaTitleNode);

    }

    genreTree.setModel(new DefaultTreeModel(genreMainTree));

    }

 }

解决方法:

How can I search through the nodes to make sure I don’t end up with any duplicate categories?

保持地图以类别为键,并​​以其值为节点.

Map<String, DefaultMutableTreeNode> categoryToNode = new HashMap<>();

迭代时,检查此Map是否包含类别Node：

>如果确实将子级添加到该节点
>如果未创建,则将其添加到“树和地图”中.

例如：

DefaultMutableTreeNode universeTitleNode = categoryToNode.get(e.getValue());
if (universeTitleNode == null ){
    universeTitleNode = new DefaultMutableTreeNode(e.getValue());
    categoryToNode.put(e.getValue(), universeTitleNode);
    genreMainTree.add(universeTitleNode);
}
mediaTitleNode = new DefaultMutableTreeNode(e.getKey());
universeTitleNode.add(mediaTitleNode);

标签：jtree,hashmap,java
来源： https://codeday.me/bug/20191120/2043262.html