代码实现:求一个3*3矩阵对角线元素之和

//求一个3*3矩阵对角线元素之和
public class Test29 {
	public static void main(String[] args) {
		int[][] a = new int[][] { { 100, 2, 3, }, { 4, 5, 6 }, { 17, 8, 9 } };
		matrSum(a);
	}
	private static void matrSum(int[][] a) {
		int sum1 = 0;
		int sum2 = 0;
		for (int i = 0; i < a.length; i++)
			for (int j = 0; j < a[i].length; j++) {
				if (i == j)
					sum1 += a[i][j];
				if (j == a.length - i - 1)
					sum2 += a[i][j];
			}
		System.out.println("矩阵对角线之和分别是：" + sum1 + "和" + sum2);
	}
}