Question

I have the following code in an Android application:

public static HttpResponse dbPost(String handlerUrl, List<NameValuePair> postData) {

    HttpClient httpclient = new DefaultHttpClient();
    String postUrl = constants.postUrl(); 
    HttpPost httppost = new HttpPost(postUrl);
    HttpResponse response = null;
    System.out.print("Catch 0");

    try {
        httppost.setEntity(new UrlEncodedFormEntity(postData));
        response = httpclient.execute(httppost);
    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    } catch (ClientProtocolException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

    System.out.print("Catch 1");

    return response;

}

I have a button that calls this block. If I press the button, the console will print “Catch 0” (but NOT “Catch 1”). If I press the button again (same instance), the console will print “Catch1Catch0”. What’s the problem?

I’m a bit new to Java so bear with me.

Answer 1

You need to call flush since you’re using print.

System.out.print("Catch 1");
System.out.flush();

The default behavior of PrintStream is to only flush when a newline is written. (This behavior is documented in write(int).)

If you used printLn instead of print, the stream would flush automatically. Without that, you need to explicitly flush the output stream.