Question

I have the following code, which checks for the number of rows in the database.

private void checkMMSRows(){
    Cursor curPdu = getContentResolver().query(Uri.parse("content://mms/part"), null, null, null, null);
    if (curPdu.moveToNext()){
        int number = curPdu.getCount();
        System.out.println(number);
    }
}

I will to run this code every second and do something when the value has changed. The problems is, how do I go about “detecting” the change? Any help would be appreciated.

Answer 1

Very basically, add a class variable – you can either make it static across all instances of the class, or an instance variable (by removing the static keyword).

Each time you get a number, you can compare it to oldNumber. After the comparison, set the oldNumber to the current number – so you have something to compare against next time:

private static int oldNumber = -1;
private void checkMMSRows(){
    Cursor curPdu = getContentResolver().query(Uri.parse("content://mms/part"), null, null, null, null);
    if (curPdu.moveToNext()){
        int number = curPdu.getCount();
        System.out.println(number);
        if(number != oldNumber){
            System.out.println("Changed");
            // add any code here that you want to react to the change
        }
        oldNumber = number;
    }
}

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Update:

My answer’s a straight code hack & slash solution, but I’d probably recommend amit’s answer.