자바 2차원 배열 최댓값 구하기

최댓값 구하기. 

import java.util.Arrays;
import java.util.Comparator;

public class Main {

    static int find_max(int[][] arrays) {
        int max = 0;
        for (var array : arrays)
            for (var element : array)
                if (element > max) max = element;
        return max;
    }

    static int find_max2(int[][] arrays) {
        return Arrays.stream(arrays)
                .map(array -> Arrays.stream(array).max().orElseThrow())
                .max(Comparator.naturalOrder()).orElseThrow();
    }

    static int find_max3(int[][] arrays) {
        return Arrays.stream(arrays)
                .flatMapToInt(Arrays::stream)
                .max().orElseThrow();
    }

    public static void main(String[] args) {
        var array2d = new int[][]{{1, 2, 3}, {4, 5, 6}, {7, 8, 9, 0}};
        System.out.println(Arrays.deepToString(array2d));
        System.out.println(find_max(array2d));
        System.out.println(find_max2(array2d));
        System.out.println(find_max3(array2d));
    }
}

 

참고 

https://homoefficio.github.io/2019/10/03/Java-Optional-%EB%B0%94%EB%A5%B4%EA%B2%8C-%EC%93%B0%EA%B8%B0/