Question

Look at the following method header: public static vold mymethod (double[] array) Here is an array declaration: double[] numbers = new double [100] Write a statement that passes the numbers array to the myMethod method.

Short answer

Answer: To call the "mymethod" and pass the "numbers" array as an argument, use the following statement: mymethod(numbers);

Step-by-step solution

Verify method header and declared array

We have the method header: public static void mymethod (double[] array) And we have the declared array: double[] numbers = new double [100] We need to call the method by passing the 'numbers' array as a parameter.

Call the method and pass the array

To call the "mymethod" and pass the "numbers" array, simply use this statement: mymethod(numbers);

Key concepts

Java Method Header

Understanding the method header in Java is crucial for invoking methods correctly. The method header specifies the method's return type, name, and parameters. Consider the exercise method header:

public static void mymethod(double[] array)

The public keyword means that the method is accessible from any other class. static indicates that the method belongs to the class itself rather than an instance of the class, which allows us to call the method without creating an object of the class. The void keyword informs us that the method does not return any value after it is executed. The method name, mymethod, is how we refer to and invoke the method. Finally, the parameters within the parentheses, double[] array, tell us that this method takes a single argument, which is an array of double values. When calling this method, you must provide an array of doubles so that the method can operate on it.

Array Declaration in Java

In Java, arrays are used to store multiple values of the same type in a single variable, instead of declaring separate variables for each value. The exercise provided us with the following array declaration:

double[] numbers = new double[100];

The syntax starts with the data type of the array (double in this case), followed by square brackets to denote it's an array. The array name (numbers) comes next, and finally, it is instantiated with the new keyword followed by the data type again and the size of the array in square brackets—indicating that we have an array that can hold 100 elements of type double. Array indexes in Java are zero-based, meaning the first element is at index 0, and the last element is at index 99 in this case. It is important to initialize arrays correctly to avoid runtime errors.

Passing Arrays to Methods

Passing an array to a method allows you to pass the reference of an array without creating a new copy of the array. In the exercise, we pass the 'numbers' array to 'mymethod' as demonstrated in the solution:

mymethod(numbers);

When you pass an array to a method, you're passing the array's memory address, not the entire array itself. This means that any changes to the array within the method will affect the original array. It's a powerful feature that can be used to manipulate an array in various methods without the overhead of copying the array each time. Always ensure that the method you're calling is compatible with the array you're passing, and that the array is properly instantiated to prevent errors or unexpected behavior.