Are assert statements ignored during runtime?

Issue

With following codes,

public Some persist(final Some entity) {
    if (flag) {
        super.persist(entity);
        entity.credentials();
        update(entity);
        return entity;
    }
    assert super.persist(entity).equals(entity);
    assert entity.credentials().equals(entity);
    assert update(entity);
    return entity;
}

if the flag is false, it seems statements are ignored and not executed.

Is it normal? Or some assertion failed?

I already know how to enable assertion.

What I want to know is that the whole assert ... statement is ignored or not regardless of enabling the -ea option.

I'm trying them with my spring library and it seems that the whole statement which means the code yielding the boolean flag are ignored.

What I want to know is that

1. Is the only the functionality of assertion ignored, or
2. The whole statement are ignored.

I'm sharing what I learned. It's pretty shocking to me.

public Some persist(final Some entity) {

    // WORKS!
    super.persist(entity);
    entity.generate();
    update(entity);
    return entity;

    // WORKS!
    final Some persisted = super.persist(entity);
    assert persisted.equals(entity);
    final Some generated = entity.credentials();
    assert generated.equals(persisted);
    final boolean updated = update(generated);
    assert updated;
    return generated;

    // DOES NOT WORK!!! SHOULDN'T DO THIS!!!
    assert super.persist(entity).equals(entity);
    assert entity.generate().equals(entity);
    assert update(entity);
    return entity;
}

Solution

What I want to know is that the whole assert ... statement is ignored or not regardless of enabling the -ea option.

Yes, it will be ignored entirely unless assertions are enabled. This is useful as a way to detect whether they're enabled at runtime:

boolean assertionsEnabled = false;
assert assertionsEnabled = true;
System.out.println("Assertions enabled: " + assertionsEnabled);

Answered By - shmosel