Suppressed Exceptions in Try-With-Resources

Direct Answer

When the try body throws and closing also throws, the body exception remains primary and each close failure is attached through addSuppressed; callers inspect them with getSuppressed(). If the body succeeds, the first close failure is primary and later close failures are suppressed. A naive manual finally can replace an earlier failure, but careful manual code can preserve it too.

Code Example

The body error is caught as primary; the close() error shows up under getSuppressed().

static class Faulty implements AutoCloseable {
    public void work() { throw new RuntimeException("primary: work failed"); }
    public void close() { throw new RuntimeException("suppressed: close failed"); }
}

public static void main(String[] args) {
    try (Faulty f = new Faulty()) {
        f.work();                        // throws primary
    } catch (RuntimeException e) {
        System.out.println(e.getMessage());              // primary: work failed
        for (Throwable s : e.getSuppressed()) {
            System.out.println("  " + s.getMessage());   // suppressed: close failed
        }
    }
}

The body's exception is primary; the close() failure is preserved as suppressed, not lost.

Common Mistakes & Pitfalls

• Assuming the close() exception wins. In try-with-resources, the body exception is primary.
• Forgetting getSuppressed() exists. The close failure is still recorded — go read it.
• Replicating the old finally bug by manually closing and rethrowing in a way that drops the original.
• Ignoring 'Suppressed:' lines in a stack trace — they often explain a secondary cleanup failure.