Java 7 introduced the try-with-resources statement, which guarantees that the resource in question will be closed. Since the new syntax is closer
to bullet-proof, it should be preferred over the older try
/catch
/finally
version.
This rule checks that close
-able resources are opened in a try-with-resources statement.
Note that this rule is automatically disabled when the project's sonar.java.source
is lower than 7
.
FileReader fr = null; BufferedReader br = null; try { fr = new FileReader(fileName); br = new BufferedReader(fr); return br.readLine(); } catch (...) { } finally { if (br != null) { try { br.close(); } catch(IOException e){...} } if (fr != null ) { try { br.close(); } catch(IOException e){...} } }
try ( FileReader fr = new FileReader(fileName); BufferedReader br = new BufferedReader(fr) ) { return br.readLine(); } catch (...) {}
or
try (BufferedReader br = new BufferedReader(new FileReader(fileName))) { // no need to name intermediate resources if you don't want to return br.readLine(); } catch (...) {}