Question

Hello I want to Fill Up my Arraylist of Arraylist named as QuestionIdList_Section
and for that i have make the temp Arraylist named QUESTION_ID_Of_SectionId_Temp that will be clear after adding into QuestionIdList_Section

My Code is as Below so that you can understand how i have codded :

public static ArrayList<String> QUESTION_ID_Of_SectionId_Temp = new ArrayList<String>();
public static ArrayList<ArrayList<String>> QuestionIdList_Section = new ArrayList<ArrayList<String>>();

QUESTION_ID_Of_SectionId_Temp.add("Hello");
QUESTION_ID_Of_SectionId_Temp.add("Hiii");

QuestionIdList_Section.add(0,QUESTION_ID_Of_SectionId_Temp);

Log.i(TAG, "******Before " + QuestionIdList_Section);
Log.i(TAG, "******Before "+ QUESTION_ID_Of_SectionId_Temp);

QUESTION_ID_Of_SectionId_Temp.clear();

Log.i(TAG, "******After  " + QuestionIdList_Section);
Log.i(TAG, "******After " + QUESTION_ID_Of_SectionId_Temp);

After Executing the Code i am getting Different Result for both Variable.

as Below :

******Before [[Hello, Hiiii]]
******Before [Hello, Hiiii]
******After [[]]
******After []

can some one Please Help me to Understand where i am lacking here. i want to clear temp arraylist so that i can put the different Values for UESTION_ID_Of_SectionId_Temp so for second index of QuestionIdList_Section i will set the Value different.

Thanks in Advance.

Answer 1

QUESTION_ID_Of_SectionId_Temp is just a reference.

So if you clear it, the value in QuestionIdList_Section will also be clear.

What you should do is

QUESTION_ID_Of_SectionId_Temp = new ArrayList<String>();

instead of

QUESTION_ID_Of_SectionId_Temp.clear();