由SQL查詢填充的Java Jtree

Question

我想從將從SQL查詢中導入的二維對象數組創建JTree。這是SQL表的樣子：

這裏是對象的樣品：

Object[][] table = { 
     {1, 0, "Root"}, //i=0 
     {2, 1, "Node2"}, //i=1 
     {3, 1, "Node3"}, //i=2 
     {4, 1, "Node4"}, //i=3 
     {5, 4, "Node5"}, //i=4 
     {6, 4, "Node6"}, //i=5 
     {7, 4, "Node7"}, //i=6 
     {8, 1, "Node8"}, //i=7 
     {9, 1, "Node9"}, //i=8 
     {10, 9, "Node10"},}; //i=9 

這裏是我使用對數組進行排序的邏輯：

for (int i = 0; i < table.length; i++) { 
     for (int j = i; j < table.length; j++) { 
      if (table[i][0] == table[j][1]) { 
       System.out.println(table[i][2].toString() + " is parent of " + table[j][2].toString()); 
      } 
     } 
    } 

這是上面什麼在控制檯顯示：

Root is parent of Node2 
Root is parent of Node3 
Root is parent of Node4 
Root is parent of Node8 
Root is parent of Node9 
Node4 is parent of Node5 
Node4 is parent of Node6 
Node4 is parent of Node7 
Node9 is parent of Node10 

我很努力創建TreeModel，HashTable，對象等，我可以用來創建JTree。

我一直在這個問題上停留了一個多星期，我現在可以真正使用他人的經驗。

Answer 1

我是Java新手，所以我不得不對這個問題做一些研究。這項研究非常耗時。我發現以下鏈接具有從SQL數據創建JTree的最佳解決方案。

https://forums.oracle.com/forums/thread.jspa?threadID=2225475

這裏是我用於解決問題

class myTree extends JPanel { 

private DefaultMutableTreeNode rootNode; 
private DefaultTreeModel treeModel; 

public myTree() { 

    super(new GridLayout(1, 1)); //Set the layout for the panel that the jtree. 

    //The following object is a sample from a database and was used to validate 
    //the solution below. Make sure the table is properly sorted before you create the 
    //the object from the query. 
    Object[][] table = { 
     {1, null, "Root"}, //i=0 
     {2, 1, "Node2"}, //i=1 
     {3, 2, "Node3"}, //i=2 
     {4, 3, "Node4"}, //i=3 
     {5, 4, "Node5"}, //i=4 
     {6, 5, "Node6"}, //i=5 
     {7, 6, "Node7"}, //i=6 
     {8, 1, "Node8"}, //i=7 
     {9, 1, "Node9"}, //i=8 
     {10, 9, "Node10"},}; //i=9 

    //Create as many nodes as there are rows of data. 
    DefaultMutableTreeNode[] node = new DefaultMutableTreeNode[table.length]; 
    for (int i = 0; i < table.length; i++) { 
     node[i] = new DefaultMutableTreeNode(table[i][2].toString()); 
    } 

    rootNode = node[0]; //Set the root node 

    //Cycle through the table above and assign nodes to nodes 
    for (int i = 0; i < table.length; i++) { 
     for (int j = 1; j < table.length; j++) { 
      if (table[i][0] == table[j][1]) { 
       System.out.println(table[i][2].toString() + " is parent of " + table[j][2].toString()); 
       node[i].add(node[j]); 
      } 
     } 
    } 
    //Creating the tree model. setting the root node. 
    treeModel = new DefaultTreeModel(rootNode); 
    //Setting the tree model to the JTree 
    JTree tree = new JTree(treeModel); 
    //adding the tree to the JPanel 
    add(tree); 
} 

Answer 2

整理數據到這些列：

CREATE TABLE tree_node 
(NodeID int, 
ParentID int, 
Value varchar(250) 
...) //as many values per node as you want 

這將允許您遍歷記錄並填充JTree的。

看看depth first和breadth first樹遍歷。