仅当设备具有txt文件时，我才能使apk起作用吗？

Question

How can I make my apk to function only if my device has a txt file? I have an apk that I have made.

Is there a way to make it work only if the device its installed on has a specific text file which I can input anything in and it won't work if the device doesn't have the file.

Answer 1

You can check for your file in onCreate method of your launcher activity. If the file exists, you can do whatever you want like creating an intent to MainActivity and if it does not exist, you can finish your app :

File file = new File(filePath);
if(file.exists()) {
    // Do Something 
}
else {
    // Close the app
    finish();
}