Find the error in each of the following program segments. Explain how to correct the error. 

a)
    void g() {
    System.out.println("Inside method g");

    void h() {
    System.out.println("Inside method h");
    }
    }

b)
    int sum(int x, int y) {
    int result;
    result = x + y;
    }

c)
    void f(float a); {
    float a;
    System.out.println(a);
    }

d)
    void product() {
    int a = 6;
    int b = 5;
    int c = 4;
    int result = a * b * c;
    System.out.printf("Result is %d%n", result);
    return result;
    }