每次显示活动时运行一种方法

Question

I have an if statement checking if there are any rows in a sqlite database. If there are rows existing in the database it enables some buttons, if not it will disable the buttons.

like so

DBHandler dbHandler = new DBHandler(this, null, null, 1);
    SQLiteDatabase db = dbHandler.getWritableDatabase();
    String count = "SELECT count(*) FROM clients";
    Cursor mcursor = db.rawQuery(count, null);
    mcursor.moveToFirst();
    int icount = mcursor.getInt(0);
    if(icount == 0)
    {
        btnViewClient.setEnabled(false);
        btnViewAppt.setEnabled(false);
        btnAddAppt.setEnabled(false);
        btnViewBill.setEnabled(false);
        btnAddBill.setEnabled(false);
    }
    else
    {
        btnViewClient.setEnabled(true);
        btnViewAppt.setEnabled(true);
        btnAddAppt.setEnabled(true);
        btnViewBill.setEnabled(true);
        btnAddBill.setEnabled(true);
    }

that is in my onCreate method.

So now if the user adds a row into the sqlite database and hits the back button returning to the main menu. How can I run this code again and enable the buttons? I need to run this code every time the activity is shown, but I don't want to finish the activity because then you can't use the back button to return to it.

Answer 1

You might want to learn a bit more about Activity Lifecycle .

Particularly, you need to use onResume method - it will be called every time your app will return to your Activity .

So just put your code above to this method.