Java Arrays 클래스

Arrays로 배열 다루기

문자열 비교와 출력

• equals()
• toString()

int[] arr = {0, 1, 2, 3, 4};
int[][] arr2D = {{11, 22}, {33, 44}};

System.out.println(Arrays.toString(arr)); // [0, 1, 2, 3, 4]
System.out.println(Arrays.deepToString(arr2D)); // [[11, 22], [33, 44]]

int[][] int2D = {{11, 22}, {33, 44}};
int[][] int2D2 = {{10, 20}, {30, 40}};

System.out.println(Arrays.equals(arr2D, int2D)); // 1차원 배열 비교이므로 false
System.out.println(Arrays.deepEquals(arr2D, int2D)); // true
System.out.println(Arrays.deepEquals(arr2D, int2D2)); // false

배열의 복사

• copyOf()
• copyOfRange()

import java.util.Arrays;

public class EX5_9 {
    public static void main(String[] args) {
        int[] arr = {0, 1, 2, 3, 4}; // [0, 1, 2, 3, 4]
        int[] arr2 = Arrays.copyOf(arr, arr.length); // [0, 1, 2, 3, 4]
        int[] arr3 = Arrays.copyOf(arr, 3); // [0, 1, 2]
        int[] arr4 = Arrays.copyOf(arr, 7); // [0, 1, 2, 3, 4, 0, 0]
        int[] arr5 = Arrays.copyOfRange(arr, 2, 4); // [2, 3]
        int[] arr6 = Arrays.copyOfRange(arr, 0, 7); // [0, 1, 2, 3, 4, 0, 0]

        System.out.println(Arrays.toString(arr));
        System.out.println(Arrays.toString(arr2));
        System.out.println(Arrays.toString(arr3));
        System.out.println(Arrays.toString(arr4));
        System.out.println(Arrays.toString(arr5));
        System.out.println(Arrays.toString(arr6));

    }
}

배열의 정렬(오름차순 정렬)

• sort()

import java.util.Arrays;

public class EX5_10 {
    public static void main(String[] args) {
        int[] arr = {3, 1, 2, 4, 0};
        System.out.println(Arrays.toString(arr)); // [3, 1, 2, 4, 0]
        Arrays.sort(arr);
        System.out.println(Arrays.toString(arr)); // [0, 1, 2, 3, 4]

    }
}