The InputStream stream has been closed, but the file or folder cannot be deleted, indicating that it is occupied by the JVM

Sometimes liumingming is closed , But you still can't delete files or folders , Prompt by JVM Occupation, etc

public void download(String sourceUrl, String targetPathFile) {
        URL url = null;
        // Download a picture from the Internet 
        InputStream inputStream = null;
        OutputStream outputStream = null;
        // Set up a network link 
        HttpURLConnection con = null;
        try {
            url = new URL(sourceUrl);
            con = (HttpURLConnection) url.openConnection();
            inputStream = con.getInputStream();
            outputStream = new FileOutputStream(new File(targetPathFile));
            int n = -1;
            byte b[] = new byte[1024];
            while ((n = inputStream.read(b)) != -1) {
                outputStream.write(b, 0, n);
            }
            outputStream.flush();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if(inputStream!=null)
                inputStream.close();
            } catch (IOException e1) {
                e1.printStackTrace();
            }
            try {
                if(outputStream!=null)
                outputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
   }

In such a time , This can usually be done :

                    System.gc();// Call garbage collection before deleting , such jvm It won't occupy the file 
                    try {
                        Thread.sleep(100);// This is my side , If you don't sleep for a while , Still unable to delete 
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    boolean dirFile = FileUtils.deleteQuietly(new File(targetDirPath));
                    boolean zipFile = FileUtils.deleteQuietly(new File(targetZipPathFile));