Recursive queries about child nodes

  recursive   child nodes

encountered this problem, ask for advice .

I have a class like this

public class GeographicalArea {

private String name;
private ArrayList subAreas; / / This is the child node
private ArrayList containedBy; / / This is the parent node

. . . . . .

public GeographicalArea [] getAreayWithSubarea () {

/ / I want to achieve here return all child nodes
}
}

help. . Thank
------ Solution --------------------------------------- -----

	public GeographicalArea[] getAreaWithSubarea() {
  		ArrayList<GeographicalArea> list = this.getSubarea();
  		GeographicalArea[] areas = new GeographicalArea[list.size()];
  		int i = 0;
  		for (GeographicalArea area : list) {
  			areas[i++] = area;
  		}
  		return areas;
  	}
  	
  	private ArrayList<GeographicalArea> getSubarea() {
  		ArrayList<GeographicalArea> areas = new ArrayList<>();
  		for (GeographicalArea area : this.subAreas) {
  			areas.add(area);
  			areas.addAll(area.getSubarea());
  		}
  		return areas;
  	}

------ For reference only --------------------------- ------------
yesterday, you just ask the parent node of it. . Today asked the child node . .
You 'd think for themselves about , ah, such a basic issue of any book on this are basically able to speak it very clear
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. . . . Thought out . . . .
I continue to think about . . . .
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In fact, I have achieved depending on your method of recursive child nodes , but only print it, how can there not written into the array . . . .
sorry.
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so I finally resolved . I have no way to put the results of written array , because this method is called recursively many times, so I re- wrote a class to recursion. Posted :
private List areaArray = new ArrayList ();
public void recursionFn (GeographicalArea area) {
if (area.getSubAreas ()! = null && area.getSubAreas (). size ()> 0) {
areaArray.add (area);
Iterator childIT = area.getSubAreas () iterator ().;
while (childIT.hasNext ()) {
GeographicalArea node = (GeographicalArea) childIT.next ();
recursionFn (node);
}
} else {
areaArray.add (area);
}

}



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  private List<GeographicalArea> areaArray = new ArrayList<GeographicalArea>();
  public void recursionFn(GeographicalArea area){
  if(area.getSubAreas()!=null && area.getSubAreas().size() >0){
  areaArray.add(area);
  Iterator<GeographicalArea> childIT = area.getSubAreas().iterator();
  while(childIT.hasNext()){
  GeographicalArea node = (GeographicalArea)childIT.next();
  recursionFn(node);
  }
  }else{
  areaArray.add(area);
  }
  
  }
  
  

adjust the format of java, easy for everyone to see .
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still thank you for helping .
knot a tie .