The method getString(int) is undefined for the type Apps

pass a instance of Context context

and then use

context.getResources().getString(R.string.text1)

here context is belongs to your current activity.

First getString is not a static method, you are calling it in a static context this can't be done.

Second the getString method is part of the Resources class, your class does not extend the Resources class so the method can't be found.

I think parsing an instance of the Resources class to your Apps class using its constructor would be your the best option.

Something like this:

public final class Apps {

    public Apps(Resources r){
     DIALOGUE = new String[]{
        r.getString(R.string.text1),
        r.getString(R.string.string2),
        r.getString(R.string.string3)};
    }


/**
 * Our data, part 1.
 */
public static final String[] TITLES =
{
        "title1",
        "title2",
        "title3"
};

/**
 * Our data, part 2.
 */
public static String[] DIALOGUE;
}