Saving Data on Android

Wri/ng to internal storage
Open 
MainActivity.kt
. Notice the code immediately above 
onCreate()
:
private
 
val
 repo: NoteRepository 
by
 lazy 
{ InternalFileRepository(
this
) }
This is a lazy value. It represents an object of a class that implements 
NoteRepository
. There’s a separate implementation for each storage type 
demonstrated in this chapter.
The 
repo
 is initialized the first time it’s used and will be utilized throughout 
MainActivity
. This includes the button click events that call the add, get and delete 
methods required by 
NoteRepository
.
Saving Data on Android
Chapter 1: Using Files
raywenderlich.com
22

---

In 
onCreate()
, locate 
btnWrite.setOnClickListener
 add the following code for 
the 
WRITE
 button’s click event:
// 1
 
if
 (edtFileName.text.isNotEmpty()) { 
  
// 2
 
  
try
 { 
    
// 3
 
    repo.addNote(Note(edtFileName.text.toString(), 
        edtNoteText.text.toString())) 
  } 
catch
 (e: Exception) { 
// 4
 
    showToast(
"File Write Failed"
) 
  } 
  
// 5
 
  edtFileName.text.clear() 
  edtNoteText.text.clear() 
} 
else
 { 
// 6
 
  showToast(
"Please provide a Filename"
) 
}
Here’s how it works:
1. Use an 
if/else
 statement to ensure the user entered the required information.
2. Put 
repo.addNote
 into a 
try/catch
 block. Writing a file can fail for different 
reasons like permissions or trying to use a disk with not enough space available.
3. Call 
addNote()
, passing in a 
Note
 that contains the filename and text provided 
in the 
EditText
 fields.
4. If writing the file fails, display a 
Toast
 message and write the stacktrace of the 
error to Logcat.
5. To prepare the interface for the next operation, clear the text from 
edtFileName
 
and 
edtNoteText
.
6. If the user did not enter a filename, display a toast message within the 
else
 
block. 
showToast
 is a utility function that exists in