保存到sdcard android时图像被覆盖

Question

I want to save multiple images in a folder on sdcard but when saving new image, previous ones gets overwritten. How can I save multiple images in my folder?

    File mydirectory =  new File(Environment.getExternalStorageDirectory() + "/AppFolder");
    if(!mydirectory.exists()){

        mydirectory.mkdir();
    }

    if(mydirectory.exists()){
        try {
            File root = new File(Environment.getExternalStorageDirectory() +"/AppFolder");


            File sdImageMainDirectory = new File(root , "pic.png");
            outputFileUri = Uri.fromFile(sdImageMainDirectory);
            startCameraActivity();

        } catch (Exception e) {
            Toast.makeText(MainActivity.this, "Error occured. Please try again later.",Toast.LENGTH_SHORT).show();

            finish();
        }
    }
}

private void startCameraActivity() {
    // TODO Auto-generated method stub

    Intent cameraIntent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
    cameraIntent.putExtra(MediaStore.EXTRA_OUTPUT, outputFileUri);
    startActivityForResult(cameraIntent, 101);
}

Answer 1

You are saving each file with name as pic.png .

You need to change the file name each time.

Edit:

In addition to answer by @David Xu, if you want to have unique name each time, you can just append a unix timestamp at the end of the file name as follows

dImageMainDirectory = new File(root, "pic_" + (System.currentTimeMillis() / 1000L) + ".png");

Answer 2

change

File sdImageMainDirectory = new File(root , "pic.png");

to

File sdImageMainDirectory = null;
int i = 0;
do {
   sdImageMainDirectory = new File(root, "pic-" + i + ".png");
   i++;
} while (sdImageMainDirectory.exists());

Answer 3

You are using the same name for every picture which is why it is getting overwritten

File sdImageMainDirectory = new File(root , "pic.png");

you are naming them all pic.png

Try developing a naming convention like pic1.png, pic2.png or you can save the png as the name of the current timestamp like this:

//get timestamp into string
DateFormat df = new SimpleDateFormat("MM/dd/yyyy HH:mm:ss");
Date today = Calendar.getInstance().getTime();        
String timeStamp = df.format(today);

File sdImageMainDirectory = new File(root , timeStamp + ".png");

Answer 4

Every file you create has the same name. Here's a quick and dirty solution:

            try{
                File root = new File(Environment.getExternalStorageDirectory() +"/AppFolder");

                int i = 0;
                File sdImageMainDirectory = new File(root , "pic.png");
                while(sdImageMainDirectory.exists()){
                     i++
                     sdImageMainDirectory = new File(root , "pic" +i+ ".png");
                }
                outputFileUri = Uri.fromFile(sdImageMainDirectory);
                startCameraActivity();

             } catch (Exception e) {