Java 8 Array Stream Filter

Question

I have one simple array with custom object and want to filter with java 8 stream.

    A[] aArray = new A[3];

    A a1 = new A();
    a1.setaId(1);
    a1.setaName("AName1");

    B b1 = new B();
    b1.setbId(1);
    b1.setbName("BName1");

    a1.setB(b1);
    aArray[0] = a1;

    A a2 = new A();
    a2.setaId(2);
    a2.setaName("AName2");

    B b2 = new B();
    b2.setbId(2);
    b2.setbName("BName2");

    a2.setB(b2);
    aArray[1] = a2;

Can you please suggest how can I go for filter stream on array NOT ON arrayList

Basically I want to filter with only "BName2" value.

Your array size should be 2. So the declaration should be changed like: A[] aArray = new A[2]; — Ravindra Ranwala
– Ravindra Ranwala, Commented Mar 10, 2019 at 5:04
As an aside define yourself some good constructors so you may do just A[] aArray = new A[] { new A(1, "AName1", new B(1, "BName1")), new A(2, "AName2", new B(2, "BName2")), null };. — Anonymous
– Anonymous, Commented Mar 10, 2019 at 8:18

Mayur · Accepted Answer · 2019-03-10 06:17:50Z

1

If you are storing unique element in the array then you can use following approach

If the object is Unique

A aWithValidString = Arrays.stream(aArray)
    .filter(a -> "BName2".equals(a.getB().getbName()))
    .finAny().orElse(null);

If you have multiple Objects in Array with "Bname2" string you can use Below code

List<A> filteredObject = Arrays.stream(aArray)
    .filter(a -> "BName2".equals(a.getB().getbName()))
    .collect(Collectors.toList());

And Iterate List

edited Mar 10, 2019 at 6:17

answered Mar 10, 2019 at 5:48

Mayur

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3 Comments

Boris the Spider Over a year ago

Calling Optional.get is always a mistake.

Mayur Over a year ago

@BoristheSpider Corrected, Thanks :)

ByeBye Over a year ago

.orElse(null) always gives me depression... With Optional why do you even want to use null? You can just return Optional and that all - no sense to mapping it to null

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