Java/Multi-dimensional array/이차원배열

ex1

	int[][] kor = new int[3][5];// 3개반 5명
		Random rd = new Random();

		System.out.println(kor + "," + kor.length);//// kor은 참조값을 가르킴
		System.out.println(kor[0] + "," + kor[0].length);/// kor.length는 칸의 갯수
		System.out.println(kor[1] + "," + kor[1].length);
		System.out.println(kor[2] + "," + kor[2].length);

		// for (int i = 0; i < 3; i++) 3은 kor.length
		// for (int j = 0; j < 5; j++) 5는 kor[].length 로 치환
		for (int i = 0; i < kor.length; i++) {
			for (int j = 0; j < kor[1].length; j++) {
				kor[i][j] = rd.nextInt(100);
			}
		}

		for (int i = 0; i < 3; i++) {
			for (int j = 0; j < 5; j++) {
				System.out.print(kor[i][j] + ",");
			}
			System.out.println();
		}

[[I@6d06d69c,3
[I@7852e922,5
[I@4e25154f,5
[I@70dea4e,5
35,91,31,91,41,
93,21,8,36,19,
95,7,99,8,50,

 

 

ex2

declaire 4x6 arrays, assign numbers from 1 and print all.

int[][] test = new int[4][6];

		int cnt = 0;/// 숫자대입할변수설정
		// 데이터대입용
		for (int i = 0; i < test.length; i++) {
			for (int j = 0; j < test[i].length; j++) {
				test[i][j] = ++cnt;// 숫자계속 대입 test안의 칸이 다찰때 까지
			}
		}

		// 데이터출력용
		for (int i = 0; i < test.length; i++) {
			for (int j = 0; j < test[i].length; j++) {
				System.out.print(test[i][j] + ", ");

			}

			System.out.println();
		}

1, 2, 3, 4, 5, 6, 
7, 8, 9, 10, 11, 12, 
13, 14, 15, 16, 17, 18, 
19, 20, 21, 22, 23, 24, 

 

 

ex3

/*
		    ┌[][][][]
		[0][1][2]:arr
		ㄴ[][]  ㄴ[][][]
		
		*/
		int[][] arr = new int[3][];
		arr[0] = new int[2];
		arr[1] = new int[4];
		arr[2] = new int[3];// 총 9개의 저장공간
		int cnt = 0;

		for (int i = 0; i < arr.length; i++) {
			for (int j = 0; j < arr[i].length; j++) {
				arr[i][j] = ++cnt;
			}
		}

		for (int i = 0; i < arr.length; i++) {
			for (int j = 0; j < arr[i].length; j++) {
				System.out.print(arr[i][j] + ",");
			}
			System.out.println();
		}

1,2,
3,4,5,6,
7,8,9,