增强Java代码以提高效率

Question

I am trying to expand a GWT tree using selenium and i did successfully with that code

for (int i = 0; i < elem.size(); i++) {
 if (!elem.get(i).isExpanded() || !elem.get(i).isLeaf()) {
  elem.get(i).toggleExpand();
 }
 for (int j = 0; j < elem.get(i).getChildren().size(); j++) {
  if (!elem.get(i).getChildren().get(j).isExpanded() || 
                        !elem.get(i).getChildren().get(j).isLeaf()) {
   elem.get(i).getChildren().get(j).toggleExpand();
  }
  for (int k = 0; k < elem.get(i).getChildren().get(j).getChildren().size(); k++) {
   if (!elem.get(i).getChildren().get(j).getChildren().get(k).isExpanded() ||
              !elem.get(i).getChildren().get(j).getChildren().get(k).isLeaf()) {
    elem.get(i).getChildren().get(j).getChildren().get(k).toggleExpand();
   }.....
  }
 }
}

My question is how to enhance that code or how to put in recursive method ?

Answer 1

To make that code more readable there are a few things you could do (:

Reuse method results, eg that of elem.get(i) or use an extended for-loop (if elem etc. support that):

for (int i = 0; i < elem.size(); i++) {
  ElementClass element = elem.get(i);
  if (!element.isExpanded() || !element.isLeaf()) {
    element.toggleExpand();
  }

  ...
}

Additionally since you seem to do the same for the element and it's children you could provide a method eg:

public void expandIfNeeded(ElementClass element) {
  if (!element.isExpanded() || !element.isLeaf()) {
    element.toggleExpand();
  }
}

Then you loop could look like this:

for (int i = 0; i < elem.size(); i++) {
  ElementClass element = elem.get(i);
  expandIfNeeded( element );

  ... //handle children here and call the same method for those (could also be using recursion)
}

Additionally, if you don't need the index i and elem is iterable you could use the extended for:

for ( ElementClass element : elem ) {
  expandIfNeeded( element );

  ... //handle children here and call the same method for those (could also be using recursion)
}

And of course recursion would make it more readable, especially if you don't know the depth of the tree:

//I'm assuming "elem" is a List<ElementClass> here
public void expandElements( List<ElementClass> elem ) {
  for ( ElementClass element : elem ) {
    expandIfNeeded( element );
    expandElements( element.getChildren() );
  }
}

Answer 2

Unreadable code.

Try something like this:

for (int i = 0; i < elem.size(); i++) {
  if (!elem.get(i).isExpanded()) {
    elem.get(i).toggleExpand();
  }
  // I don't know what this method returns; no time to research for you
  List<Element> children = elem.get(i).getChildren();
  for (int j = 0; j < children.size(); j++) {
      // don't know what you call it; must be a void method of some kind
      yourMethodName(children.get(i));
  }
}

Answer 3

You can recursively toggled the element by using following code.

public static void toggleElement(Element elem){

        if(elem.isExpand() || elem.isLeaf()){
            return;
        }else{
            elem.toggledExpand();
        }
        List<Element> children=elem.getChildren();
        for (int i = 0; i < children.size(); i++) {
            toggleElement(children.get(i));
        }
    }

Hopefully it will resolve your problem.