Java issue - how to force my code to exit when it hangs

I have a Java method that I use for decrypting files by executing the GPG binary and passing in some parameters (see code sample below).

Sometimes for reasons beyond my control, the file that the program is attempting to decrypt is corrupted and cannot be decrypted.  In those cases, I want the program to abort and raise an error.  The problem I am having is that the the program often just hangs and never completes - it is as if it were stuck in an infinite loop.  So rather than trapping the problem and exiting, the program just sits there and never completes.

Is there any way I can force this program so that it will ALWAYS complete - either successfully or by raising an error?

Thanks.

	public static String decryptFile(String gpgBinaryPath, String passphrase,
			 String decryptedFilePath, String encryptedFilePath) {

		//System.out.println("encryptedFilePath: " + encryptedFilePath);
		//System.out.println("decryptedFilePath: " + decryptedFilePath);
		//System.out.println("gpgBinaryPath: " + gpgBinaryPath);
		//System.out.println("passphrase: " + passphrase);
		
		String strExecReturn = "";
		
		String[] cmdArray = new String[] {
				gpgBinaryPath,
				"--no-tty",
				"--yes",
				"-q",
				"-d",
				"--passphrase",
				passphrase,
				"-o",
				decryptedFilePath,
				encryptedFilePath };
		java.lang.Runtime runtime = java.lang.Runtime.getRuntime();
		java.lang.Process ps = null;
		try 
		{
			ps  = runtime.exec(cmdArray);
		} //end try
		catch (IOException e) 
		{
			// TODO Auto-generated catch block
			e.printStackTrace();
		}//end catch - IOException
		try
		{
			int exitStatus = ps.waitFor();
			//System.out.println ("exit Status = "+exitStatus);
			if(exitStatus!=0)
			{
				InputStream e = ps.getErrorStream();
				String error = "";
				
				BufferedInputStream bre = new BufferedInputStream(e);
				try 
				{
					int readInt = bre.read();
					System.out.println ("readInt = "+readInt);
					while (readInt != -1) 
					{
						char c = (char) readInt;
						error = error + c;
						readInt = bre.read();
					}//end while
				}//end try 
				catch (IOException e1) 
				{
					e1.printStackTrace();
				}//end catch
				
				System.out.println("ERROR_COMMAND "+ error);
				strExecReturn = "ERROR:"+error;
				throw new Exception("Some problem while copying - "+error);
			}//end if
			else if(exitStatus==0)
			{
				strExecReturn = "SUCCESS";
			}//end else if
		}//end try
		catch (java.lang.InterruptedException e) 
		{
			System.out.println("EXCEPTION_TRACE "+ e);
			e.printStackTrace();
		}//end catch - InterruptedException
		catch(Throwable t)
		{
			t.printStackTrace();
		}//end catch - Throwable
		//System.out.println("Hello " + message + " !"); //$NON-NLS-1$ //$NON-NLS-2$
		
		return strExecReturn;
	}//end method - decryptFile

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