Styjun

In many try-with-resource examples I have searched, Statement and ResultSet are declared separately. As the Java document mentioned, the close methods of resources are called in the opposite order of their creation.

try (Statement stmt = con.createStatement();
 ResultSet rs = stmt.executeQuery(sql) ) 

 catch (Exception e) 

But now I have multiple queries in my function.

Can I make Statement and ResultSet in just one line ? My code is like:

try (ResultSet rs = con.createStatement().executeQuery(sql);
 ResultSet rs2 = con.createStatement().executeQuery(sql2);
 ResultSet rs3 = con.createStatement().executeQuery(sql3)) 

 catch (Exception e) 

If I only declare them in one line, does it still close resource of both ResultSet and Statement?

When you have a careful look you will see that the concept is called try-with-resources.

Note the plural! The whole idea is that you can declare one or more resources in that single statement and the jvm guarantees proper handling.

In other words: when resources belong together semantically, it is good practice to declare them together.

Yes, and it works exactly as you put it in your question, multiple statements separated by semicolon.

You may declare one or more resources in a try-with-resources statement. The following example retrieves the names of the files packaged in the zip file zipFileName and creates a text file that contains the names of these files:

 try (
 java.util.zip.ZipFile zf =
 new java.util.zip.ZipFile(zipFileName);
 java.io.BufferedWriter writer = 
 java.nio.file.Files.newBufferedWriter(outputFilePath, charset)
) 
 // Enumerate each entry
 for (java.util.Enumeration entries =
 zf.entries(); entries.hasMoreElements();) 
 // Get the entry name and write it to the output file
 String newLine = System.getProperty("line.separator");
 String zipEntryName =
 ((java.util.zip.ZipEntry)entries.nextElement()).getName() +
 newLine;
 writer.write(zipEntryName, 0, zipEntryName.length());
 

https://docs.oracle.com/javase/tutorial/essential/exceptions/tryResourceClose.html

ResultSet implements AutoCloseable, which means try-with-resources will also enforce closing it when it finishes using it.

https://docs.oracle.com/javase/7/docs/api/java/sql/ResultSet.html