Get Variable from another Activity (Android Studio)

Question

I know that there are a lot of answers to this question already, but I'm still having trouble dealing with this concept.

An answer found here shows:

If you didn't want to use a global variable you could always create a method in your activity to return your string.

    public String getMyString(){
         return item; } 

Then in your current activity you could call:

    String myValue = LoginScreen.getMyString();

When I try this method, I am returned an error saying "Non-Static method can not be referenced from a static context". However if I make the method static it says that my variable needs to be static, but I need to update the variable. I'll include my code below.

---

First Activity -

btnSEARCH.setOnClickListener(new View.OnClickListener() {
    public void onClick(View view) {
        if (editTextSearch.getText().toString() != null) {
            SearchQueryTerm = editTextSearch.getText().toString();
            editTextSearch.setText("");
        }
    }
});

public String getMyString(){
    return SearchQueryTerm;
}

Second Activity-

String SearchQueryTerm = MainActivity.getMyString();

---

I truly appreciate any help you can give me in this. Thanks so much!! <3

---

This is my updated code - however it still crashes :(

Activity 1

public void sendMessageIntent(View view) {
    Intent search_intent = new Intent(this, SearchActivity.class);
    api_intent.putExtra("my_variable", SearchQueryTerm);
    startActivity(search_intent);
}

xml file

 <Button
        android:id="@+id/button_view"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="right"
        android:text="View"
        android:onClick="sendMessageIntent"
        />

Activity 2 -

public String SearchQueryTerm

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

        if (extras != null) {
            SearchQueryTerm = extras.getString("my_variable");
        }
}

Answer 1

Use putExtra method of an object Intent.

In your first activity create for example :

String value = "value";
Intent i = new Intent(getApplicationContext(), MyActivity.class);
i.putExtra("my_variable",value);
startActivity(i);

In your second activity you can retrieve your variable :

Bundle extras = getIntent().getExtras();
if (extras != null) {
    String value = extras.getString("my_variable");
}

It's the best method to pass a variable between activities.

---

To show you how it works, i have done this code :

XML of first activity :

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
    android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">
        <EditText
            android:id="@+id/editTextSearch"
            android:layout_width="200dp"
            android:layout_height="wrap_content" />

        <Button
            android:id="@+id/buttonSearch"
            android:layout_width="200dp"
            android:layout_height="wrap_content"
            android:text="Button"/>
    </LinearLayout>

</RelativeLayout>

First Activity :

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Button btnSEARCH = (Button) findViewById(R.id.buttonSearch);

        btnSEARCH.setOnClickListener(new View.OnClickListener() {
            public void onClick(View view) {
                EditText editTextSearch = (EditText) findViewById(R.id.editTextSearch);
                if (editTextSearch.getText().toString() != null) {
                    String value = "value";
                    Intent i = new Intent(getApplicationContext(), Main2Activity.class);
                    i.putExtra("SearchQueryTerm",editTextSearch.getText().toString());
                    startActivity(i);
                    editTextSearch.setText("");
                }
            }
        });
    }

}

In this first activity we pass the value of the editText in the putExtra method with the key = "SearchQueryTerm".

To retrieve the value of editText do this in your second Activity :

public class Main2Activity extends AppCompatActivity {

    String SearchQueryTerm = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);

        Bundle extras = getIntent().getExtras();
        if (extras != null) {
            SearchQueryTerm = extras.getString("SearchQueryTerm");
        }

        System.out.println(SearchQueryTerm);
    }

}

Now you have the value of your editText in the variable SearchQueryTerm ( Second Activity ).

It works for me, so there is no reason it dont work for you.

Hope it helps.

Answer 2

a good solution is to add a "model" singleton class, where you store data that have to be shared between your activities

example :

public class Model {
private static Model __instance == null;

private Model() {
}

public static Model instance() {
    if (__instance == null) {
        __instance = new Model();
    }
    return __instance;
}

private Object mydataToShare = null;

public void setMyDataToShare(Object mydataToShare) {
    this.mydataToShare = mydataToShare; 
}

public Object getMyDataToShare() {
    return mydataToShare;
}

}

to store data :

Model.instance().setMyDataToShare(<value to store>);

to retrieve data :

Object valueToRetrieve = Model.instance().getMyDataToShare();

it allow you to transfer complex data and separate completely logic part from UI