How to display the decrypted file in Java without File Output? [migrated]

I am trying to develop a system that will decrypt a file then allows the authorized user to view it without saving the decrypted file. This is to ensure that the other user won't be able to open the decrypted file.

The following codes produced a file output.

    public NewJFrame() {try{
                String key = "squirrel123";
                FileInputStream fis2 = newFileInputStream("encrypted.mui");
                FileOutputStream fos2 = new FileOutputStream("decrypt.rar");

                decrypt(key, fis2, fos2);
                Desktop dk=Desktop.getDesktop();
                File f = new File("decrypt.rar");
                dk.open(f);
            }
                catch (Throwable e) {
         JOptionPane.showMessageDialog(null, e);
    }}  
    public static void decrypt(String key, InputStream is, OutputStream os) throws Throwable {
    encryptOrDecrypt(key, Cipher.DECRYPT_MODE, is, os);
}

public static void encryptOrDecrypt(String key, int mode, InputStream is, OutputStream os) throws Throwable {

    DESKeySpec dks = new DESKeySpec(key.getBytes());
    SecretKeyFactory skf = SecretKeyFactory.getInstance("DES");
    SecretKey desKey = skf.generateSecret(dks);
    Cipher cipher = Cipher.getInstance("DES"); // DES/ECB/PKCS5Padding for SunJCE

    if (mode == Cipher.ENCRYPT_MODE) {
        cipher.init(Cipher.ENCRYPT_MODE, desKey);
        CipherInputStream cis = new CipherInputStream(is, cipher);
        doCopy(cis, os);
    } else if (mode == Cipher.DECRYPT_MODE) {
        cipher.init(Cipher.DECRYPT_MODE, desKey);
        CipherOutputStream cos = new CipherOutputStream(os, cipher);
        doCopy(is, cos);
    }
}

public static void doCopy(InputStream is, OutputStream os) throws IOException {
    byte[] bytes = new byte[64];
    int numBytes;
    while ((numBytes = is.read(bytes)) != -1) {
        os.write(bytes, 0, numBytes);
    }
    os.flush();
    os.close();
    is.close();
}

How can I decrypt a file without using FileOutputStream then allows the authorized user to view it after the decryption?