CalculateAreaParallelogram()

Step 1: Declare method signature

The first step is to define the method signature for the function. In Java, this would usually include the visibility modifier, the return type, the method name, and any input parameters. For our function, we'll make it public, specify a return type of double - since area is generally a decimal number, name it 'calcAreaParallelogram', and define two input parameters of type double which represent the base and height.

public double calcAreaParallelogram(double base, double height) {
}

Step 2: Write the calculation formula inside the method

Next, we will use the formula for the area of a parallelogram, which is base multiplied by height. We'll create a variable 'area' to hold the calculation result.

public double calcAreaParallelogram(double base, double height) {
    double area = base * height;
}

Step 3: Return the area

After calculating the area, we need to return the value. This can be done using the 'return' keyword.

public double calcAreaParallelogram(double base, double height) {
    double area = base * height;
    return area;
}

Step 4: Test the method

Now that our method is implemented, we can test it by calling the method with sample parameters and printing the result.

public static void main(String[] args) {
    System.out.println(calcAreaParallelogram(5, 4)); // should print 20.0
}

Conclusion:

We've now successfully implemented a method to calculate the area of a parallelogram in Java. The full code implementation is as follow:

public class Main {
    public static void main(String[] args) {
        System.out.println(calcAreaParallelogram(5, 4)); // should print 20.0
    }
    public static double calcAreaParallelogram(double base, double height) {
        double area = base * height;
        return area;
    }
}