Android's memory leak because of HttpClient

Question

Hi there, sorry for my English.

I'm developing an Android application, consisting in various activities and a service which is activated by "main" activity. The service checks every 3 seconds (this interval is arbitrary) about active network connections into mobile phone. If there's a connection to a PC inside my local network, I then make a call to a web server there.

The problem is, I try to reach host PC through this function:

public boolean checkNet() { HttpClient client; HttpPost postMethod; HttpParams httpParams; URI uri;

try { uri = new URI(Const.HOST_ADDRESS); postMethod = new HttpPost(uri); postMethod.addHeader("Content-Type", "text/xml");

httpParams = postMethod.getParams(); HttpConnectionParams.setSoTimeout(httpParams, 1000); HttpConnectionParams.setSocketBufferSize(httpParams, 512); HttpConnectionParams.setStaleCheckingEnabled(httpParams, false); HttpConnectionParams.setConnectionTimeout(httpParams, 1000);

client = new DefaultHttpClient(); } catch (URISyntaxException use) {}

try { client.execute(postMethod); return true; } catch (ClientProtocolException cpe) {

} catch (IOException e) { } return false; }

I do use this method, instead of checking WifiManager's and internal Android methods, because I have a situation like this: I can be connected to an open-encryption AP, but it has a login system (coova). Here, I can be associated (and have an IP inside LAN), but if I'm not logged I won't have access to any network, so I have to implement a "network-checking-wrapper".

So, if there was an exception in execute function because my host PC isn't reachable, DDMS will show me how heap size and allocation size will grow without control. I suspect that it's because of the sub-calls inside "execute" don't properly close obsolete references... for instance, here's a example of allocation tracker:

java.lang.AbstractStringBuilder enlargeBuffer AbstractStringBuilder.java 99 false java.lang.AbstractStringBuilder append0 AbstractStringBuilder.java 170 false java.lang.StringBuilder append StringBuilder.java 224 false org.apache.http.conn.HttpHostConnectException HttpHostConnectException.java 48 false org.apache.http.impl.conn.DefaultClientConnectionOperator openConnection DefaultClientConnectionOperator.java 133 false org.apache.http.impl.conn.AbstractPoolEntry open AbstractPoolEntry.java 164 false org.apache.http.impl.conn.AbstractPooledConnAdapter open AbstractPooledConnAdapter.java 119 false org.apache.http.impl.client.DefaultRequestDirector execute DefaultRequestDirector.java 348 false

Thanks in advance.

Answer 1

Well I've already noticed one problem. You have 2 separate try-catch blocks. The first one catches a URISyntaxException. You then, in your second try-catch, call client.execute(). But if there's an exception in your first catch, client may not be instantiated and your second try-catch will result in an NPE.