Add all Java tree nodes and its own value to HashMap using java

Question

I have a JavaTree ,its all node has a name and assigned value. I want to add these names and values to HashMap. But, I can't take all results to HashMap finally. It take only one value in one time. I used following code.

public HashMap<String, Double> printAll(TreeNode root) {

  HashMap<String, Double> allContainNodes = new HashMap<String, Double>();
  NodeInfor nodeObj = (NodeInfor) ((DefaultMutableTreeNode) root).getUserObject();

  Enumeration children = root.children();

  if (children != null) 
    while (children.hasMoreElements()) {
      printAll((TreeNode) children.nextElement());
    }
  }

  allContainNodes .put(nodeObj.name, nodeObj.specVal);
  return allContainNodes;
}

Thank you for your reply. It didn't give any error message. But, I can't take all results to HashMap finally. It take only one value in one time. — Emalka
– Emalka, Commented Jun 8, 2016 at 14:33

Loic Mouchard · Accepted Answer · 2016-06-08 14:54:31Z

2

You could for example pass the instance of the HashMap to the next level of the iteration, modifying your method like following (only the first run should instanciate it),

public HashMap<String, Double> printAll(TreeNode root, HashMap<String, Double> allContainNodes) {

  if (allContainNodes==null){
   allContainNodes = new HashMap<String, Double>();
  }
  NodeInfor nodeObj = (NodeInfor) ((DefaultMutableTreeNode) root).getUserObject();

  Enumeration children = root.children();

  if (children != null) 
    while (children.hasMoreElements()) {
      printAll((TreeNode) children.nextElement(), allContainNodes );
    }
  }

  allContainNodes.put(nodeObj.name, nodeObj.specVal);
  return allContainNodes;
}

answered Jun 8, 2016 at 14:54

Loic Mouchard

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1 Comment

Emalka Over a year ago

Thank you very much for your reply.

michael_bitard · Accepted Answer · 2016-06-08 14:41:53Z

1

You lose the printAll values in your recursive call, try something like

allContainNodes.putAll(printAll((TreeNode) children.nextElement()));

answered Jun 8, 2016 at 14:41

michael_bitard

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2 Comments

Emalka Over a year ago

You mean instead of allContainNodes .put(nodeObj.name, nodeObj.specVal); ? It gave an error

Exception in thread "main" java.util.NoSuchElementException 	at java.util.Collections$EmptyEnumeration.nextElement(Unknown Source)

michael_bitard Over a year ago

No, i meant instead of printAll((TreeNode) children.nextElement()); in your loop

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