import java.io.File;

import java.io.IOException;

import java.util.Random;

public class TempFileDemo{

public static void main(String[] args) throws IOException{

System.out.println("default relative/user directory: " + System.getProperty("user.dir")); // current directory where JVM lanched from.

System.out.println("default temp directory: " + System.getProperty("java.io.tmpdir"));

File tempFile = File.createTempFile("text", ".txt");

System.out.println("tempFile pathname: " + tempFile);

System.out.println("tempFile existing: " + tempFile.exists());

tempFile.deleteOnExit(); // delete the file after JVM terminated.

try{

System.out.println("Simulating operations for 5 seconds...");

Thread.sleep(5000);

// during this period, you can observe tempFile existing and deleting.

}catch(InterruptedException ie){

ie.printStackTrace();

}

Random random = new Random();

if(random.nextBoolean()){

System.out.println("Simulating error occured before application terminated normally.");

throw new NullPointerException("Fake Exception Just for Demo Intention.");

// Still can not simulate the deleting failure scenario through uncaught exception, which may be handled by JVM itself.

// Finally, I succeed to simulate what I expect through terminating the Terminal application with force. Then the tempFile was not deleted.

}

System.out.println("Application is terminating.");

}

}