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
– Dyna, Commented Feb 3, 2014 at 15:38
Possible duplicate of What is a Null Pointer Exception, and how do I fix it? — Krease
– Krease, Commented Dec 15, 2015 at 16:09

ρяσѕρєя K · Accepted Answer · 2014-02-03 15:52:44Z

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 3, 2014 at 15:52

answered Feb 3, 2014 at 15:28

ρяσѕρєя K

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3 Comments

Sweety Bertilla Over a year ago

Even after initializing I am getting the same error

Sweety Bertilla Over a year ago

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 Over a year ago

I changed the condition check to cache.size() >i and it worked. if i=0, size of the cache should be at least 1.

Pete B. · Accepted Answer · 2014-02-03 15:45:38Z

0

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.

answered Feb 3, 2014 at 15:45

Pete B.

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