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Learn Java: Arrays


Throughout the lesson, we have learned about:

  • Creating arrays explicitly, using { and }.
  • Accessing an index of an array using [ and ].
  • Creating empty arrays of a certain size, and filling the indices one by one.
  • Getting the length of an array using length.
  • Using the argument array args that is passed into the main() method of a class.



In order to practice the skills you’ve learned throughout the lesson, we’re going to make and use some arrays in the main() method of a new Classroom class.

First, inside main(), make a String array called students, and set it equal to the following students, in order:

Sade Alexus Sam Koma

Now, we’re going to store the averages on the most recent math test. Create an array called mathScores and set it to an empty array of size 4. It should hold doubles.


Sade got a 94.5 on the test. Store this value in the 0th index of the mathScores array.


Sam got a 76.8 on the test. Store this value in the appropriate spot in the mathScores array.


Write a print statement to say:

The number of students in the class is <numStudents>.

with <numStudents> replaced by the length of the students array.

For example, if the array has 7 elements, the printout should read:

The number of students in the class is 7.
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