Stream, Collectors

a.java

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

class a {
    public static void main(String[] args) {
        Integer[] array= new Integer[] {1, 2, 3, 4, 5};
        List<Integer> list= Arrays.asList(array);
        System.err.println("sum:"+list.stream().mapToInt(Integer::intValue).sum());
        System.err.println("average:"+list.stream().mapToInt(Integer::intValue).average().getAsDouble());
        //
        System.err.print("rotate:"+list);
        Collections.rotate(list, 2);
        System.err.println(" -> "+list);
        //
        System.err.println("sum:"+list.stream().collect(Collectors.summingInt(Integer::intValue)));
        System.err.println("ave:"+list.stream().collect(Collectors.averagingInt(Integer::intValue)));
        System.err.println("min:"+Collections.min(list));
        System.err.println("max:"+Collections.max(list));
        System.err.println(list.stream().sorted((o1, o2)->o1.compareTo(o2)).collect(Collectors.toList()));
    }
}