Getting a string from an intent , getting null object reference error?

[Joshua Harris]

Hello,

So I'm simply trying to pass a string to another activity using intent.putExtra(name, value); but for some reason the activity receiving the intent is saying it's a null reference. I have no idea why, because I've basically just copied the exact same code from a different activity which is performing the same task correctly.

Here is my code:

@Override
        protected void onPostExecute(Void result) {
            super.onPostExecute(result);

            dialog.dismiss();

            tierOneLV.setAdapter(tierOneAA);

            tierOneLV.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                @Override
                public void onItemClick(AdapterView<?> adapterView, View view, int position, long l) {

                    itemposition = position;

                    onClick(view);
                }
            });
        }

    @Override
    public void onClick(View view) {


        Intent intent = new Intent(getApplicationContext(), TierTwoListView.class);
        name = tierOneAA.getItem(itemposition).toString();
        intent.putExtra("name", name);
        intent.putExtra("id", id);
        startActivity(intent);

    }

and here is the code for where the intent is received:

public class TierTwoListView extends Activity implements View.OnClickListener {

    ListView tierTwoLV;
    ArrayAdapter<String> tierTwoAA;
    private static String url_base = "http://www.webfleetsystems.co.uk/wbfleet/defects/getdefectlist.ashx";
    private static String url = "getdefectlist.ashx";
    String name;
    String t1defect = getIntent().getStringExtra("name");
    String t1id = getIntent().getStringExtra("id");
    ProgressDialog dialog;
    String LOG_TAG = "LOG: " + getClass() + "";

here is the error msg: Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Intent.getStringExtra(java.lang.String)' on a null object reference
at com.example.testing_load.TierTwoListView.<init>(TierTwoListView.java:33)

(java line 33 is line 8 in the code snippet i provided)

as I said earlier I am using basically the exact same code to perform this task in other activities and it's working fine. It's probably a very simple and stupid mistake but I'd be grateful if someone could point out why the error is occurring.

[Maneesh Godbole]

The first step to debug this would be to confirm the value being set is actually not null. Have you tried checking what is the value at this point?

    intent.putExtra("id", id);

[Joshua Harris]

Maneesh Godbole wrote:The first step to debug this would be to confirm the value being set is actually not null. Have you tried checking what is the value at this point?

    intent.putExtra("id", id);

I just edited the code to give me log tags, here they are:

09-08 12:09:55.196 1362-1362/com.example.testing_load D/LOG: class com.example.testing_load.TierOneListView﹕ VALUE OF name IS: ENGINE
09-08 12:09:55.196 1362-1362/com.example.testing_load D/LOG: class com.example.testing_load.TierOneListView﹕ VALUE OF id IS: 3

so the id string is definitely not null.

[Maneesh Godbole]

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Intent.getStringExtra(java.lang.String)' on a null object reference

Check the getIntent() for null

[Joshua Harris]

Maneesh Godbole wrote:

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Intent.getStringExtra(java.lang.String)' on a null object reference

Check the getIntent() for null

Oh right, what do you mean? Sorry I'm a very beginner at android. How do I check getIntent for null?

[Joshua Harris]

Maneesh Godbole wrote:

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Intent.getStringExtra(java.lang.String)' on a null object reference

Check the getIntent() for null

Well I just added this code instead:

        if (getIntent().hasExtra("name")){

            t1defect = getIntent().getStringExtra("name");
        }

and it seems to be working now... I don't understand why?

[Joshua Harris]

Maneesh Godbole wrote:

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Intent.getStringExtra(java.lang.String)' on a null object reference

Check the getIntent() for null

I realise my mistake now. I was calling the getIntent() method outside of the onCreate method.

As soon as I moved the code calling getIntent() inside the onCreate method it's all working fine. Stupid mistake lol.