How to call method from another class without passing context?

Question

I am currently trying to call a method from a utility class that will reference a new cursor created for this utility method. Unfortunately, my new class will not let me create the cursor without context. I have tried numerous ways of passing context from the calling activity, but get null pointer exceptions in most cases.

Here is the portion of my code:

findViewById(R.id.button).setOnClickListener(new View.OnClickListener() {
                public void onClick(View v) {
                        Tools.pickRandomItem();

                    }
});

and in the Tools Class:

     public static void pickRandomItem() {   

    Cursor cur = getContentResolver().query(MediaStore.Audio.Media.EXTERNAL_CONTENT_URI, null, 
               null, null,MediaColumns.TITLE + " ASC");




}

Using the above code it throws an error on getContentResolver(), and all attempts I've made to pass context have failed.

I am fairly new to programming for Android, and don't fully understand the concept of contexts. Any help you could provide would be greatly appreciated!

Even though this question is older, better discussion and clearer answers are happening on this duplicate question: http://stackoverflow.com/questions/7666589/using-getresources-in-non-activity-class — tir38, May 02 '16 at 19:31

score 7 · Accepted Answer · answered Nov 14 '10 at 13:54

7

Create a class that extends Application for your project (you have to declare it in the Manifest too), in the Application make a

private static MyApplication app

in the onCreate() of it assign it to the field

app = this;

and make a

public static MyApplication get()

in it. When you need a Context you can use a

MyApplication.get()

answered Nov 14 '10 at 13:54

apps

942
5
8

1

I guess getApplicationContext() is another way of doing the same. – Rakesh Sep 13 '12 at 07:32
use getApplicationContext() – Nitin Bansal Feb 02 '13 at 03:51

score 2 · Answer 2 · answered Nov 14 '10 at 14:57

2

A few hints on Context:

Get Context in you View via getContext() and pass it to getContentResolver(context).
Use application-context approach as described here by @apps.
Don't store context inside Activity or Views. This leads to memory leaks.

answered Nov 14 '10 at 14:57

Peter Knego

79,991
11
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Thank you for the advice. Through your advice and more reading I have learned how critical context handling is to memory management. – Josh Nov 15 '10 at 02:09

How to call method from another class without passing context?

2 Answers2

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