ArraysTask3ArrayPositiveFinder.java

package HomeWork;

/**
 * Created by Andrey on 27.12.2015.
 */
public class ArraysTask3ArrayPositiveFinder {
    public static void main(String[] args) {
        int[] array = {3, -5, -1, 4, -2, -5};
        System.out.println(findFirstPositive(array));
        System.out.println(findLastPositive(array));
    }

    public static int findFirstPositive(int[] array) {
        int result = 0;
        for (int i = 0; i < array.length; i++) {
            if (array[i] > 0) {
                return result;
            }
            result++;
        }
        if (array[result - 1] > 0) {
            return result;
        } else {
            return -1;
        }
    }

    public static int findLastPositive(int[] array) {
        int result = 5;
        for (int i = array.length - 1; i > 0; i--) {
            if (array[i] > 0) {
                return result;
            }
            result--;
        }
        if (array[result] > 0) {
            return result;
        } else {
            return -1;
        }
    }
}

ArraysTask6MatrixPrinter.java

package HomeWork;

/**
 * Created by Andrey on 30.12.2015.
 */
public class ArraysTask6MatrixPrinter {
    public static void main(String[] args) {
        int height = 8;
        int length = height;
        double[][] matrix = new double[height][length];
        printMatrix(matrix);
    }

    public static double[][] printMatrix(double[][] matrix) {

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

ArraysTask7MatrixAverageCalculator.java

package HomeWork;

/**
 * Created by Andrey on 30.12.2015.
 */
public class ArraysTask7MatrixAverageCalculator {
    public static void main(String[] args) {
        double[][] matrix = {{0, 3, -2}, {2, 1, 3}, {-1, 5, 2}};
        System.out.println(calculateAverage(matrix));
    }

    public static double calculateAverage(double[][] matrix) {
        double sum = 0;
        int n = 0;
        for (int i = 0; i < matrix.length; i++) {
            for (int j = 0; j < matrix.length; j++) {
                sum += matrix[i][j];
                n++;
            }
        }
        return sum / n;
    }
}