Using variable of one class in another class - Java

Question

I have two classes. the first one is MainActivity and the other is Orders The MainActivity.java is as follows

 public class MainActivity extends Activity implements
            ProductListAdapterListener {
        private static final String TAG = MainActivity.class.getSimpleName();
        public String itms1,itms2,itms3;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


    @Override
        public void onAddToCartPressed(Product product) {
            if(x==0)
            {
                itms1=",";
            }
            x++;
            PayPalItem item = new PayPalItem(product.getName(), 1, product.getPrice(), Config.DEFAULT_CURRENCY,product.getSku());
            productsInCart.add(item);
                itms2 = item.getName();
            itms2=itms2.concat(", ");
            itms1=itms2.concat(itms1);
                Toast.makeText(getApplicationContext(),
                        item.getName() + " added to cart! the cart now has:" + itms1, Toast.LENGTH_LONG).show();
            }

    }

Here, I am trying to use the variable itms1 in another class Orders.java which is as follows:

 public class Orders extends MainActivity {
        Button email, text;
        public String msg=itms1;
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.orders);
            email = (Button) findViewById(R.id.email);
            text = (Button) findViewById(R.id.text);
         text.setOnClickListener(new View.OnClickListener() {

                @Override
                public void onClick(View v) {
                    final String message = msg;

    //check whether the msg empty or not

                        final HttpClient httpclient = new DefaultHttpClient();
                        final HttpPost httppost = new HttpPost("http://ramsproject.16mb.com/sendorder.php");
                        Thread thread = new Thread(new Runnable(){
                            @Override
                            public void run() {

                                try {
                                    List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
                                    nameValuePairs.add(new BasicNameValuePair("id", "01"));
                                    nameValuePairs.add(new BasicNameValuePair("message",message));
                                    httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
                                    httpclient.execute(httppost);
                                    Toast.makeText(getBaseContext(), "Sent", Toast.LENGTH_SHORT).show();
                                } catch (Exception e) {
                                    e.printStackTrace();
                                }
                            }
                        });
                        thread.start();


                }


            });

        }
    }

Here, when I try to use variable itms1 in Orders.java, i get the value of itms1 as null. How do i use the value of that variable as it is as in MainActivity.java in another class?

Possible duplicate of [What's the best way to share data between activities?](http://stackoverflow.com/questions/4878159/whats-the-best-way-to-share-data-between-activities) — Nir Alfasi, Mar 10 '16 at 05:05
You are initialising the item1 only if Add To Cart is Pressed right ?.. — Sunil Sunny, Mar 10 '16 at 05:09
do not extend MainActivity. make item1 variable public and static. and access in Order class as MainActivity.item1. Assign it to String msg inside onCreate Method. or as per you need. — vabhi vab, Mar 10 '16 at 05:10

score 0 · Answer 1 · edited Mar 10 '16 at 05:12

0

In this line: public String itms1,itms2,itms3;

itms1 is declared but was never initialized.

The reason you are getting null is because your variable has not been initialized and only takes a value within the onAddToCartPressed() method.

edited Mar 10 '16 at 05:12

VVN

1,607
2
16
25

answered Mar 10 '16 at 05:10

fndg87

331
4
13

score 0 · Accepted Answer · answered Mar 10 '16 at 05:10

0

You can declare the variable itms1 as public static by doing so you can access it by its class name (like MainActivity.itms1 ).

If you have still doubt comment below.

Hope this will helpful .

answered Mar 10 '16 at 05:10

sahu

1,188
10
19

score 0 · Answer 3 · answered Mar 10 '16 at 05:17

0

You can have one Global class inside which you can store the variables which you want to access across activities as follows

public class Globals extends Application {String itms1;}

To access this String in another activity;

Globals g = (Globals) getApplication(); String msg = g.itms1;

Don't forget to insert this line in your AndroidMenifest.xml; android:name=".Globals"

answered Mar 10 '16 at 05:17

Gvs13

126
12

The global variable can be null in case user put app in background and again started the app by clicking from recent apps! So this is not best approach. – turbandroid Mar 10 '16 at 05:20
Instead use Intents to pass values from one activity to another. – turbandroid Mar 10 '16 at 05:21
@O'one I know intents works fine but please look at the requirement of his. What if he want to access the variable without calling the destination intent? – Gvs13 Mar 10 '16 at 05:27
Choice is different thing, but it's about best approach. – turbandroid Mar 10 '16 at 05:31
@O'one Here what matter is to provide solution which fits requirement. You gave best approach and I provided a best fit solution. – Gvs13 Mar 10 '16 at 05:33
Read above first comment about this. – turbandroid Mar 10 '16 at 05:35
I commented after reading all that. Now let's end up over here and let him implement the approach he wants in his code. – Gvs13 Mar 10 '16 at 05:37

score 0 · Answer 4 · answered Mar 10 '16 at 14:43

0

Watch the use of that static variable...remember it will live in your memory and will be shared between different threads.

answered Mar 10 '16 at 14:43

fndg87

331
4
13

Using variable of one class in another class - Java

4 Answers4