Null Pointer exception in Arraylist

Question

I am getting null pointer exception even though I have placed the Null Check:

@Override 
    public ArrayList<DataCache> getData()   
    { 
        if(contentOf != null)
        {
            StoreData data = new StoreData(this);
            if(data!=null)
            {
                ArrayList<DataCache> cacheOf = null;
                System.out.println("Size of ContentOf"+contentOf.size());
                for (int i=0;i<contentOf.size();i++)
                {
                    System.out.println("Value of ContentOf"+contentOf.get(i).mFeed);
                    ArrayList<DataCache> cache = contentOf.get(i).mFeed.getData();
                    if (cache != null)
                        cacheOf.add(cache.get(i));
                }
                return cacheOf;
            }
        }
}

Exception:

02-03 10:19:18.770: E/AndroidRuntime(8680): FATAL EXCEPTION: main
02-03 10:19:18.770: E/AndroidRuntime(8680): java.lang.NullPointerException
02-03 10:19:18.770: E/AndroidRuntime(8680): at 
com.activity.MainFragmentActivity.getData(MainFragmentActivity.java:198)

initialize cacheOf like user @ρяσѕρєя K said will solve your problem! — Dyna, Feb 03 '14 at 15:38
Possible duplicate of [What is a Null Pointer Exception, and how do I fix it?](http://stackoverflow.com/questions/218384/what-is-a-null-pointer-exception-and-how-do-i-fix-it) — Krease, Dec 15 '15 at 16:09

ρяσѕρєя K · Accepted Answer · 2014-02-03T15:52:44.997

3

Also need to initialize cacheOf ArrayList before Adding elements as:

ArrayList<DataCache> cacheOf = new ArrayList<DataCache>(); //initialize here
System.out.println("Size of ContentOf"+contentOf.size());  //This will be zero.
for (int i=0;i<contentOf.size();i++) {
      //..your code here...
    if (cache != null){
       if(i<=cache.size())
         cacheOf.add(cache.get(i));
     }
}

edited Feb 03 '14 at 15:52

answered Feb 03 '14 at 15:28

ρяσѕρєя K

132,198
53
198
213

Even after initializing I am getting the same error – Sweety Bertilla Feb 03 '14 at 15:40
I removed cacheOf = null after initializing and I got the below error:02-03 10:41:53.640: E/AndroidRuntime(9143): FATAL EXCEPTION: main 02-03 10:41:53.640: E/AndroidRuntime(9143): java.lang.IndexOutOfBoundsException: Invalid index 0, size is 0 02-03 10:41:53.640: E/AndroidRuntime(9143): at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:255) 02-03 10:41:53.640: E/AndroidRuntime(9143): at java.util.ArrayList.get(ArrayList.java:308) – Sweety Bertilla Feb 03 '14 at 15:43
I changed the condition check to cache.size() >i and it worked. if i=0, size of the cache should be at least 1. – Sweety Bertilla Feb 03 '14 at 15:54

score 0 · Answer 2 · answered Feb 03 '14 at 15:45

Did you read the error?

The key here is: com.activity.MainFragmentActivity.getData(MainFragmentActivity.java:198)

What line is 198?

I suspect it is either one of these:

System.out.println("Value of ContentOf"+contentOf.get(i).mFeed);
ArrayList<DataCache> cache = contentOf.get(i).mFeed.getData();

You have memory that is uninitialized.

Null Pointer exception in Arraylist

2 Answers2