Exception Handling

Checked exceptions must be caught or declared with throws; runtime exceptions and errors are unchecked. Throw specific meaningful exceptions and catch the most specific types before general ones.

Safe boundaries

static int parsePositive(String text) {
    try {
        int value = Integer.parseInt(text);
        if (value <= 0) throw new IllegalArgumentException("positive required");
        return value;
    } catch (NumberFormatException error) {
        throw new IllegalArgumentException("invalid integer", error);
    } finally {
        // unconditional follow-up; not usually resource closing
    }
}

Preserve the cause when translating exceptions. Avoid empty catches and broad catch (Exception) except at an application boundary. finally normally runs even after return, but try-with-resources is safer for closing. Multiple resources close in reverse order and suppressed exceptions remain inspectable. Use exceptions for exceptional failure, not ordinary optional outcomes; validate early and document checked failure contracts.