There are two ways to do this
1) Use Intent
method.
In the first activity
intent.putExtra("firststring",firststring);
In the fourth activity
String first = getIntent().getExtras().getString("firststring");
So similiar process in 2nd 3rd activity.
2) Use sharedpreference method
In the first activity
public static final String MyPREFERENCES = "MyPrefs";
SharedPreferences sharedpreferences;
sharedpreferences = getSharedPreferences(MyPREFERENCES, Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedpreferences.edit(); editor.putString("firststring", firststring);
In the fourth activity
public static final String MyPREFERENCES = "MyPrefs";
SharedPreferences sharedpreferences;
sharedpreferences = getSharedPreferences(MyPREFERENCES, Context.MODE_PRIVATE);
String firststing = sharedpreferences.getString("firststring", "firststring");