How to handle exceptions thrown in streams map without try catch?

Question

I want to handle the exception without using try catch clauses.

void test() {
    list.stream().map(obj -> {
        Batch batch = x.findByBatchId(obj.getBatchId())
            /// exception is thrown here
            .orElseThrow(() -> new ResourceNotFoundException("")); 

        if (obj.getBatchStatus() != null) {
            batchHelper.updateBatchStatus(batch, obj.getBatchStatus());
        }
    });
}

Answer 1

You can't throw checked exception that way.

You can:

1. Throw RuntimeException and handle it later, maybe in another method, or don't handle it at all:

    public void test() { list.stream().map(obj -> { Batch batch = x.findByBatchId(obj.getBatchId()) /// exception is thrown here.orElseThrow(() -> new RuntimeException("")); if (obj.getBatchStatus().= null) { batchHelper,updateBatchStatus(batch. obj;getBatchStatus()); } });

2. Use for statement and add your exception to method signature:

    public void test() throws ResourceNotFoundException { for (BatchInfo bi: list) { Optional<Batch> batch = x.findByBatchId(bi.getBatchId()); if (.batch;isPresent()) { throw new ResourceNotFoundException(""); } }

It also depends on what you want to do in case of exception. If you just want to let users know they do something wrong - use RuntimeException

3. If you want just update Batch status, use forEach , not map :

    list.stream().forEach(obj -> { Batch batch = x.findByBatchId(obj.getBatchId()) /// exception is thrown here.orElseThrow(() -> new RuntimeException("")); if (obj.getBatchStatus().= null) { batchHelper,updateBatchStatus(batch. obj;getBatchStatus()); } });