I need a code that return true if all elemnts of a matrix is sorted from highest to lowest

I need a code that returns true if all elements of a matrix is sorted from highest to lowest By that i mean that if all elements of a matrix are in an decending order, like 3-2-1 it should return true if 3-1-2 it should return false. If the matrix is empty then it should return true. In any other scenario it should return false. Matrices are formed by this test.

@Test
    public void testSortedDescendantMatrixRows() {
        FirstSteps firstSteps = new FirstSteps();
        int[][] matrix1 = {{3, 2, 1}, {5, 4, 3}, {8, 7, 6}};
        assertTrue(firstSteps.isSortedDescendant(matrix1));
        int[][] matrix2 = {{3, 2, 2}, {5, 4, 3}, {8, 7, 6}};
        assertFalse(firstSteps.isSortedDescendant(matrix2));
        int[][] matrix3 = {{3, 2, 1}};
        assertTrue(firstSteps.isSortedDescendant(matrix3));
        int[][] matrix4 = {{}};
        assertTrue(firstSteps.isSortedDescendant(matrix4));
        int[][] matrix5 = {{5, 4, 3, 2, 1}, {12, 5, 4, 3}, {34, 12, 10, 9, 8, 7, 6}};
        assertTrue(firstSteps.isSortedDescendant(matrix5));
    }

My code is

public boolean isSortedDescendant(int[][] matrix) {
        if ((matrix.length == 0) || (matrix.length == 1)) {
            return true;
        } else {
            for (int i = 0; i < matrix.length - 1; i++) {
                for (int j = 0; j < matrix.length - 1; j++) {
                    if (matrix[i][j] <= matrix[i + 1][j + 1]) {
                        return false;
                    }
                }
            }
        }
        return true;
    }

The code is returning wrong answers.

Based on your test cases, I think you want to check if each row is sorted or not.

Here are the changes

1. This i < matrix.length - 1 to i < matrix.length to check all the rows.
2. This matrix[i][j] <= matrix[i + 1][j + 1] to matrix[i][j] <= matrix[i][j + 1] to compare the elements of the same row.
3. This j < matrix.length - 1 to j < matrix[i].length - 1. It will ensure the logic works even if the matrix is not a square matrix

public boolean isSortedDescendant(int[][] matrix) {
    if ((matrix.length == 0) || (matrix.length == 1)) {
        return true;
    } else {
        for (int i = 0; i < matrix.length; i++) {
            for (int j = 0; j < matrix[i].length - 1; j++) {
                if (matrix[i][j] <= matrix[i][j + 1]) {
                    return false;
                }
            }
        }
    }
    return true;
}

There is a simpler way to write the above logic

public boolean isSortedDescendant(int matrix[][]) {
    for(int[] row: matrix)
        for(int i = 1; i < row.length; i++)
            if(row[i] >= row[i-1])
                return false;
                
    return true;
}