Android Open Source - sodf Key Node

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License

The source code is released under:

Copyright (c) 2013 Lorenz Lehmann Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Sof...

Java Source Code

package lal.sodf.framework.ontology;
//from   w  ww.j  ava2 s. c  o  m
import java.util.LinkedList;
import java.util.List;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

/**
 * A node that has one or multiple children nodes, which are also KeyNodes or KeyValueNodes
 * @author Lorenz Lehmann
 *
 */
public class KeyNode extends Node{
  /** All children of this node, which can be either keys or values */
  private LinkedList<Node> children = new LinkedList<Node>();
  
  /** Create a new node */
  public KeyNode(KeyNode parent, String key){
    super(parent, key);
  }
  
  /** Create a new node */
  public KeyNode(String key){
    super(key);
  }
  
  /**
   * Add a new child to this node
   * @param child The child, which is added
   * @return True if the child was added, false if the key already existed and the node was not added 
   */
  public boolean addChild(Node child){
    if (child == null) return false;
    if (child.getKey() == null) return false;//don't add nodes without a key
    //check if any other node already has the same content, but not for nodes with a blank key
    if (!child.getKey().equals("") && getChild(child.getKey()) != null) return false;
    child.setParent(this);
    children.add(child);
    return true;
  }
  
  /**
   * Add a list of children to this node
   * @param _children The children, which are added
   * @return True if the children were added, false if one of the keys already existed and one of the nodes was not added 
   */
  public boolean addChildren(List<Node> _children){
    boolean result = true;
    for (Node n : _children){
      if (this.addChild(n) == false) result = false;
    }
    return result;
  }
  
  /**
   * Get a specific child node of this KeyNode
   * @param _child The key of the child node
   * @return The node, or null if it was not found
   */
  public Node getChild(String key){
    for (Node n : children){
      if (n.getKey().equals(key)) return n;
    }
    return null;
  }
  
  /**
   * Remove a node from the list of children
   * @param key The key of the node to be removed
   * @return The node, which has been removed or null if it did not exist
   */
  public Node removeChild(String key){
    for (Node n : children){
      if (n.getKey().equals(key)) {
        n.setParent(null);
        children.remove(n);
        return n;
      }
    }
    return null;
  }
  
  /** Get all children of this node */
  public LinkedList<Node> getChildren(){
    return children;
  }

  /* (non-Javadoc)
   * @see java.lang.Object#toString()
   */
  @Override
  public String toString() {
    return "KeyNode [key=" + key + "]";
  }

  @Override
  public KeyNode getKeyNodeChild(String key) {
    //check if the child exists
    Node selectedChild = this.getChild(key);
    if (selectedChild == null) return null;
    //make sure it is a KeyNode
    if (!(selectedChild instanceof KeyNode)) return null;
    //return the child
    return (KeyNode) selectedChild;
  }
  
  @Override
  public KeyValueNode getKeyValueNodeChild(String key) {
    //check if the child exists
    Node selectedChild = this.getChild(key);
    if (selectedChild == null) return null;
    //make sure it is a KeyNode
    if (!(selectedChild instanceof KeyValueNode)) return null;
    //return the child
    return (KeyValueNode) selectedChild;
  }
  

  @Override
  public List<KeyNode> getKeyNodeChildren() {
    List<KeyNode> results = new LinkedList<KeyNode>();
    for (Node n : children){
      if (n instanceof KeyNode) results.add((KeyNode) n);
    }
    return results;
  }

  /** 
   * Get this object and all its children as JSON representation 
   * @throws JSONException 
   */
  public JSONObject toJSON() throws JSONException{
    JSONObject result = new JSONObject();    
    //add all the children
    for (Node n : children){
      //for KeyNodes keep traversing the tree
      if (n instanceof KeyNode) result.put(n.getKey(), ((KeyNode) n).toJSON());
      else {//for KeyValue nodes stop traversing the tree but add them directly
        KeyValueNode tmp = (KeyValueNode) n;
        if (tmp.getValues().length == 1){
          //KeyValueNodes wiht only one value get added directly
          result.put(tmp.getKey(), tmp.getValues()[0]);
        }
        else if (tmp.getValues().length > 1){
          //create an array of values
          JSONArray jarr = new JSONArray();
          for (int i = 0; i < tmp.getValues().length; i++){
            jarr.put(tmp.getValues()[i]);
          }
          result.put(tmp.getKey(), jarr);
        }
        //the case of an empty KeyValueNode must not exist (unless somebody messes with the class)
      }
    }    
    return result;
  }
}

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