Example Two: How to turn an array into an ArrayList in Java using the java.util.stream API.

how-to-convert-an-array-to-an-arraylist-in-java-using-java-util-stream.groovy

@Grab(group='com.jamonapi', module='jamon', version='2.82')
import com.jamonapi.Monitor
import com.jamonapi.MonitorFactory

import static java.util.Arrays.asList

import java.util.stream.Collectors;
import java.util.List;
import java.util.Arrays;
import java.util.Random

def random = new Random()

def arrayCapacity = 10000

def numbers = new int[arrayCapacity + 1]

for (int ctr in 0..arrayCapacity) {
    numbers[ctr] = random.nextInt()
}

def iterations = 100000

def monitor = MonitorFactory.start("Convert an array to an ArrayList performance monitor via the java.util.stream example")

for (ctr in 0..iterations) {
 
  def exampleList =
    Arrays
      .stream(numbers)
      .boxed()
      .collect(
        Collectors.toList()
      ) as java.util.List

}

monitor.stop ()

println "iterations: $iterations, performance: $monitor"

return;

See the following article: How To Convert An Array To An ArrayList In Java!

Note that line #16 means we need to call the boxed method on line 31 yielding performance results that are not limited to the Java Streams API alone. If we change line #16 to use a java.lang.Integer and we remove the call to boxed on line 31 the average time to run this script five times is 8.7 seconds.