I have a list of Class1, which has a method isAvailable() which returns a boolean.
I am trying to create an array of boolean from this.
So far I have tried the below:
List<Class1> class1List;
boolean[] isAvailableArray = class1List.stream()
.map(e -> e.isAvailable())
.toArray();
However this is throwing a can't convert from Object[] to boolean[] error.
What is the reason for this.
As you can see in the following example, the stream handles the primitive boolean values correctly (it creates Boolean objects). However, when toArray is used without a generator param (constructor), it falls back to an Object array.
import org.junit.jupiter.api.Test;
import java.util.ArrayList;
import java.util.List;
import static org.junit.jupiter.api.Assertions.assertTrue;
public class BooleanStream {
public static class SomeClass {
public boolean isAvailable() {
return true;
}
}
@Test
public void testBoolean() {
List<ByteArray.SomeClass> list = new ArrayList<>();
ByteArray.SomeClass someClass = new ByteArray.SomeClass();
list.add(someClass);
Object[] isAvailableArray = list.stream().map(e -> e.isAvailable()).toArray();
assertTrue(isAvailableArray[0] instanceof Boolean);
}
}
As experiment-unit-1998x pointed out, the best solution is probably the generator param.
Boolean[] isAvailableArray = class1List.stream().map(e -> e.isAvailable()).toArray(Boolean[]::new);boolean[]? It’s very likely that whatever you want to do with the boolean array afterwards, can be done directly or at least, with an alternative way not requiring the boolean array.