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Java

J Smillie
PLUS
J Smillie
Courses Plus Student 40,123 Points
Posted by J Smillie
J Smillie
Courses Plus Student 40,123 Points

Stuck on Android Data Persistence Question

Can someone show me what I should be doing here?

I thought the question was relevant to the code written in the video preceding this challenge but I can't seem to figure out how.

The following code is similar to what you just wrote. Modify this code to only write the file if it does not already exist. Hint: Use the method from the File class that checks to see if a file exists or not.

import java.io.InputStream;
import java.io.FileNotFoundException;
import java.io.IOException;

public class FileUtilities {

  public static boolean copyResult;

  public static void saveAssetImage(Context context, String assetName) {
    File fileToWrite = new File(context.getFilesDir(), assetName);
    AssetManager assetManager = context.getAssets();

    try {
      InputStream in = assetManager.open(assetName);
      FileOutputStream out = new FileOutputStream(fileToWrite);
      copyResult = copyFile(in, out);
    } catch(FileNotFoundException e) {
      e.printStackTrace();
    } catch (IOException e) {
      e.printStackTrace();
    }
  }

  private static boolean copyFile(InputStream in, FileOutputStream out) throw IOException {

byte[] buffer = new byte[1024];
        int read;
        while((read = in.read(buffer)) != -1){
            out.write(buffer, 0, read);
    // Copy magic intentionally omitted
    return true;
  }
}

'''
Ken Alger
Ken Alger
Treehouse Teacher
Ken Alger
Ken Alger
Treehouse Teacher

Jonathan;

Did you get this issue resolved?

Ken

J Smillie
J Smillie
Courses Plus Student 40,123 Points
J Smillie
J Smillie
Courses Plus Student 40,123 Points

Hi Ken,

Nio I didn't! I decided to switch courses and come back to this...

2 Answers

Ken Alger
STAFF
Ken Alger
Treehouse Teacher
Ken Alger
Ken Alger
Treehouse Teacher

Jonathan;

Task

The following code is similar to what you just wrote. Modify this code to only write the file if it does not already exist. Hint: Use the method from the File class that checks to see if a file exists or not.

Planning

It looks like we need to alter our code where we are writing to the file, correct? That is this line here (line 16 in a new challenge):

copyResult = copyFile(in, out);

We need to make sure that we are only doing that if the file does not already exist, so we need to make some alterations.

Performing

As the instruction state, there is a method we can utilize and set it to false, since then the file does not exist. It would look something like:

fileToWrite.exists() == false

Now we need to add a conditional to it so that if the file doesn't exist, we copy our result to the file. That would look something along the lines of:

if (fileToWrite.exists() == false) { copyResult = copyFile(in, out); }

Make any sense? I hope it helps and happy coding.

Ken

Alwin Lazar V
Alwin Lazar V
5,267 Points
Alwin Lazar V
Alwin Lazar V
5,267 Points

I have solved and it works for me

public class FileUtilities {

public static boolean copyResult;

public static void saveAssetImage(Context context, String assetName) { File fileToWrite = new File(context.getFilesDir(), assetName); AssetManager assetManager = context.getAssets();

try {
  InputStream in = assetManager.open(assetName);
  FileOutputStream out = new FileOutputStream(fileToWrite);

// here I changed
if (fileToWrite.exists() == false) { copyResult = copyFile(in, out); }

} catch(FileNotFoundException e) {
  e.printStackTrace();
} catch (IOException e) {
  e.printStackTrace();
}

}

private static boolean copyFile(InputStream in, FileOutputStream out) { // Copy magic intentionally omitted return true;

} }

Happy coding