JAVA 巧用List

1:查找List中是否包含摸个元素:

List names = Arrays.asList("sunny", "nemo");

System.out.println(names.contains("nemo"));

2.将整数乘以2

List numbers = Arrays.asList(1,2,3);

System.out.println(numbers.stream().map(e -> e * 2).collect(toList()));

3. 找出比3大的偶数的倍数

public class JavaApplication1 {
    public static void main(String[] args) {
        List names = Arrays.asList("sunny", "nemso");
        System.out.println(names.contains("nemso"));
        List numbers = Arrays.asList(1,2,3,4,5,6,7);
        System.out.println(numbers.stream().map(e -> e * 2).collect(toList()));
        System.out.println(numbers.stream().filter(JavaApplication1::isGT3).filter(JavaApplication1::isEven).map(JavaApplication1::doubleIt).findFirst().get());
    }
    public static boolean isGT3(int num){
        return num > 3 ;
    }
    public static boolean isEven(int num){
        return num % 2 == 0;
    }
    public static int doubleIt(int num){
        return num * 2;
    }
}