access the variable in activity in another class

Question

In my application I need a variable from one activity to another activity without using any intent. So I have declared that variable as static and used as FirstActivity.a but this is returning so null, Hence I have created a class that extends application and declared that variable there still I am getting null. no clue how to achieve this.

Googled a lot but everyone are suggesting either to use static or extend Application class, unfortunately both are not working for me.

Application class:

public class ApplicationClass extends Application{

    private String StockName;

    public String getStockName() {
        return StockName;
    }

    public void setStockName(String stockName) {
        StockName = stockName;
    }



}

Setting the variable in one activity as:

public class Detail extends Activity{

ApplicationClass ac;

 protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.stockdetail);
        ac=new ApplicationClass();

        ac.setStockName(getIntent().getExtras().getString("StockName"));
}

Retriving the variable in another class as:

public class Table {

    Context c1;

    Cursor c;
    ApplicationClass ac=new ApplicationClass();

public String selectdate="Select " + column1 + " as _id, " + column2 + " From " + tablename + " Where " + column3 + " = " 
                                + ac.getStockName();

I'm not sure how to achieve this.

Edit

public class Detail extends Activity{

public static sname;

 protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.stockdetail);

        sname=getIntent().getExtras().getString("StockName");
}

public class Table {

        Context c1;

        Cursor c;

    public String selectdate="Select " + column1 + " as _id, " + column2 + " From " + tablename + " Where " + column3 + " = " 
                                    + Detail.sname;

Answer 1

You should define your subclassed application class in your manifest. And you should never call "new ApplicationClass()". You can get a reference to ApplicationClass instance using activity's getApplication() method.

Detail.java:

public class Detail extends Activity{

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.stockdetail);
    ApplicationClass app = (ApplicationClass)getApplication();
    app.setStockName("blah");
}
}

Table.java

public class Table {
public String selectDate;
public Table(Activity a)
{
    ApplicationClass ac=(ApplicationClass)a.getApplication();
    selectdate="Select " + column1 + " as _id, " + column2 + " From " + tablename + " Where " + column3 + " = " 
                            + ac.getStockName();
}

Instantiate Table.java

public NewActivity extends Activity{

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    Table t = new Table(this);

}
}

Answer 2

[Edited]

Since you're saying that there is a value returned from this line getIntent().getExtras().getString("StockName"), then try this code:

public class Detail extends Activity{

public static String stringValue; //make it public and static

 protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.stockdetail);

        stringValue = getIntent().getExtras().getString("StockName");
}

Now access the static object in Table class:

   public class Table {
        Context c1;
        Cursor c;

      public String selectdate="Select " + column1 + " as _id, " + column2 + " From " + tablename + " Where " + column3 + " = " + Detail.stringValue;

}

This should work properly. Make sure you're accessing the stringValue variable after the Detail activity is created.

[Original Answer]

Try this:

public class Detail extends Activity{

public static ApplicationClass ac; //make it public and static

 protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.stockdetail);
        ac=new ApplicationClass();

        ac.setStockName(getIntent().getExtras().getString("StockName"));
}

Now access the static object in Table class:

public class Table {

    Context c1;

    Cursor c;

public String selectdate="Select " + column1 + " as _id, " + column2 + " From " + tablename + " Where " + column3 + " = " 
                                + Detail.ac.getStockName();
}

P.S. To access the static object/variable, follow this syntax:

Class_Name.Object_Name.Method_Name();

Answer 3

Try this.

Step 1: Create a static Bundle object in Application class.( ApplicationClass.java)

E.g :

     public static Bundle mMyAppsBundle = new Bundle():

Step 2:

Set key values pair in that bundle from anywhere. like this:

   ApplicationClass.mMyAppsBundle.putString("key","value");

Step 3:

Now you can get these values from anywhere like this way:

   String str = ApplicationClass.mMyAppsBundle.getString("key");

Please apply null check before using bundle objects for safety points of view.

Answer 4

Try to initialize firstly your class. But what I see you want to have some application context that is accessible via application. For that porpouse you can simply use that method but data try to keep in SharedPreferences. So simply when you get sth from ApplicationClass you simply get it firstly from shared preferences and return. :) And each time when you need your ApplicationClass you initialize it and there methods run shared preferences to get data.

public class Detail extends Activity{

ApplicationClass ac = new ApplicationClass();

 protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.stockdetail);
        ac=new ApplicationClass();

        ac.setStockName(getIntent().getExtras().getString("StockName"));
}

Shared preferences context class.

public ApplicationClassWithSharedPreferences{
   private Context context;
   public ApplicationClassWithSharedPreferences(Context c){
       context = c;
   }

   public String getSomeValueFromContext(){
      SharedPreferences sharedPref = context.getPreferences(Context.MODE_PRIVATE);
      String highScore = sharedPref.getString("KEY", "DEFAULT");
      return highScore;

   }

}