Streams Quiz 4
The quiz below tests your knowledge of the material learnt in Streams - Lesson 4 - Array Type Streams.
Question 1 : The Stream.of() and Arrays.stream() methods return the same type for object type arrays?
- The <code>Stream.of()</code> and <code>Arrays.stream()</code> method DO return the same type for object type arrays.
Question 2 : What would be printed from the following code snippet?
String[] strArray = {"one", "two", "three", "four"};
Stream<String> strArrayStream = Stream.of(strArray);
System.out.println(strArrayStream.count());
- The code snippet would print 4.
Question 3 : For primitive type arrays Stream.of() calls Arrays.stream() under the bonnet?
- For primitive type arrays <code>Stream.of()</code> DOES NOT call <code>Arrays.stream()</code> under the bonnet, it only does this for object type arrays.
Question 4 : The Arrays.stream() method can deal with any primitive type?
- The <code>Arrays.stream()</code> CAN deal with any primitive by using <code>DoubleStream</code> for float primitives and <code>IntStream</code> for anything else.
Question 5 : What would be printed from the following code snippet?
Stream strArrayStream2 = Stream.of(strArray);
strArrayStream2.forEach(System.out::print);
strArrayStream2.map(String::toUpperCase)
.forEach(System.out::print);
- The code snippet will compile ok but fails with the runtime error <code>IllegalStateException</code> as the stream has already been operated upon.
Question 6 : The Stream.of() and Arrays.stream() methods return the same type for primitive type arrays?
- The <code>Stream.of()</code> and <code>Arrays.stream()</code> method DO NOT return the same type for primitive type arrays. <code>Stream.of()</code> will return a stream with a single object and <code>Arrays.stream()</code> will return either a <code>DoubleStream()</code>, <code>IntStream()</code> or <code>LongStream()</code>.
Question 7 : Which streaming method is preferred when using primitive type arrays?
- If you're streaming primitives use the <code>Arrays.stream()</code> variants that were built for this purpose.
Question 8 : For object type arrays Stream.of() calls Arrays.stream() under the bonnet?
- For object type arrays <code>Stream.of()</code> DOES call <code>Arrays.stream()</code> under the bonnet.
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What's Next?
In the next quiz we test your knowledge of numeric streams.
