How to get a documentfile uri that doesn't exist yet?

Question

I am trying to generate a Uri with a given file name that does not exist yet. I have asked for permission from the user to access this folder.

Basically, I have a tree Uri and a name, say "untitled.abc".

If untitled.abc already exists in the given directory, I want to check if untitled1.abc exists, then untitled2.abc and so on.

What I have currently doesn't work and is probably the wrong way to do this:

static Uri getUniqueDocumentUri(Context c, String name, Uri myTreeUri){
    DocumentFile folder = DocumentFile.fromTreeUri(c, myTreeUri);
    if(folder != null) {
        DocumentFile dFile = folder.createFile(".abc", name + ".abc");
        int count = 1;
        if(dFile == null) return null; //dFile IS ALWAYS NULL
        while (dFile.exists()) {
            dFile = folder.createFile(".abc", name + count + ".abc");
        }
        return dFile.getUri();
    }
    return null;

}

I don't actually want to create the files but I can't figure out how to create a uri for a file that does not exist yet. This is very easy with the normal File class:

static public String getUniqueFileName(Context c, String name, String mybasePath){
    File folder = new File(mybasePath);         
    if(!folder.exists()) folder.mkdir();        
    File file = new File(basePath + name + ".abc");
    int count = 1;      
    while(file.exists()){   
        file = new File(basePath + name + count + ".abc");
        count++;    
    }
    return file.getName();                  
}

but I just don't know how to achieve the same with DocumentFile and Uri. There must be a better way to do this, surely?

Edit: I guess what I am trying to do is create a Uri with a given name and folder.

Edit2: I have also tried this:

static Uri getUniqueDocumentUri(Context c, String name, Uri myTreeUri){
    DocumentFile folder = DocumentFile.fromTreeUri(c, Uri.parse(mytreeUri));
    if(folder != null) {
        String name1 = name + ".abc";
        int count = 1;
        while (folder.findFile(name1) != null) {
            name1 = name + count + ".abc";
            count++;
        }
        DocumentFile newdf = folder.createFile(".abc", name1);
        if(newdf == null) return null;
        return newdf.getUri(); //THIS RETURNS NULL
    }
    return null;

i need to get a well formed uri with a new file name before i can try anything. the only way i know how to do that is to create a new file which returns null. is there another way to get a uri for a file name and tree uri? — erinys, Oct 08 '21 at 01:13
Why aren't you using folder.listFiles() and then iterating through the list? — Gavin Wright, Oct 08 '21 at 01:14
I can do that to check if a file exists but I don't know how to get the Uri of a file that doesn't exist. — erinys, Oct 08 '21 at 01:21
So your only point is that you do not know how to use createFile(). You should use a mime type there instead of an extension. And if there is no suitable mime type the use `"*/*"`. — blackapps, Oct 08 '21 at 06:47

How to get a documentfile uri that doesn't exist yet?

0 Answers0