清空清单 <String> 在for循环的开始

Question

I have a for loop and it has a List, I want to make it empty every time the for loop starts.

I have this globally,

List<String> topDescription = new ArrayList<String>();

This is the for loop,

  for (int j = 0; j < subMenuArray.length(); j++) {
            JSONObject subMenuObject = subMenuArray
                    .getJSONObject(j);

            if ((subMenuObject.getString("Description"))
                    .equals(sizeSelectedItem)) {

                //empty the topDescription here

                JSONArray extraItemEntityArray = subMenuObject
                        .getJSONArray("ExtraItemEntity");

                for (int k = 0; k < extraItemEntityArray.length(); k++) {
                    JSONObject objectE = extraItemEntityArray
                            .getJSONObject(k);
                    if ((objectE.getString("Description")) != null
                            && (objectE.getString("Type"))
                                    .equals("E")) {

                        topDescription.add(objectE
                                .getString("Description"));

                    }

                }
                break;
            }

        }

Answer 1

Following is the code, but I'm not sure what you are looking for coz, every iteration it makes the list empty.

You can do this in two ways, one is just clearing and other is assigning new arraylist,

topDescription.clear();

or

topDescription = new ArrayList<Integer>();

Answer 2

为什么不进行新引用，将旧对象留给垃圾收集器？：

topDescription = new ArrayList<String>();

Answer 3

Instead of creating new reference, clearing the existing List is good. It reuses the already existing reference in the java heap but clearing the contents present in the list which makes the list to reuse with additonal overhead to JVM.