How to Use Try-With-Resources for Multiple Resources in Java 8?

How can I use try-with-resources in Java 8 to manage multiple AutoCloseable resources?

try (Connection conn = getConnection();
     Statement stmt = conn.createStatement();
     ResultSet rset = stmt.executeQuery(sql)) {
    while (rset.next()) {
        TelefonicaDataVO vo = new TelefonicaDataVO();
        vo.setTelefonicaDataId(rset.getString("Telefonica_PSD_ID"));
        vo.setReceptionDate(nvl(rset.getTimestamp("CREATION_DATE")));
        vo.setMessage(nvl(rset.getString("MESSAGE")));
        ret.add(vo);
    }
}

In Java 8, the try-with-resources statement allows you to manage multiple resources seamlessly in a single try block. This simplifies resource management significantly, especially when working with database connections and result sets.

try (Connection conn = getConnection();
     Statement stmt = conn.createStatement();
     ResultSet rset = stmt.executeQuery(sql)) {
    while (rset.next()) {
        TelefonicaDataVO vo = new TelefonicaDataVO();
        vo.setTelefonicaDataId(rset.getString("Telefonica_PSD_ID"));
        vo.setReceptionDate(nvl(rset.getTimestamp("CREATION_DATE")));
        vo.setMessage(nvl(rset.getString("MESSAGE")));
        ret.add(vo);
    }
}

Causes

• Unmanaged resources can lead to memory leaks and connection pool exhaustion.
• Multiple try blocks can cause code duplication and reduce readability.

Solutions

• Use one try block with multiple resources declared in the parentheses, separated by semicolons.
• Each resource must implement the AutoCloseable interface.

Mistake: Declaring resources within multiple try blocks, which is unnecessary.

Solution: Use a single try block to declare all resources together.

Mistake: Forgetting to implement AutoCloseable in custom classes when using try-with-resources.

Solution: Ensure all custom resources implement AutoCloseable or Closeable.