Getting Started
Download CS201_Lab04_Gradle.zip. Extract the zip file and import it into Eclipse
File→Import…→Gradle→Existing Gradle Project
You should see a project called CS201_Lab04_Gradle in the Package Explorer window.
Your task
Implement the following static methods in the ArrayAndArrayList class:
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readArray: Takes two parameters, keyboard and numElements. keyboard is a Scanner object you can use to read input from the user. numElements is the number of integer values to read. The method should return a reference to an array containing the requested number of integer values.
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printArray: Takes a parameter arr, an array of integer values. The method should print out the element values in the array.
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reverseArray: Takes a parameter arr, an array of integer values. The method should reverse the values in the elements of the array. For example, if passed an array containing the values 1 2 3, the method should re-arrange the contents of the array so that it contains the values 3 2 1.
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readArrayList: Takes two parameters, keyboard and numElements. keyboard is a Scanner object you can use to read input from the user. numElements is the number of integer values to read. The method should return a reference to an ArrayList<Integer> containing the requested number of integer values.
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printArrayList: Takes a parameter arrList, an ArrayList<Integer> of integer values. The method should print out the element values in the ArrayList.
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reverseArrayList: Takes a parameter arrList, an ArrayList<Integer> of integer values. The method should reverse the values in the elements of the ArrayList. For example, if passed an ArrayList containing the values 1 2 3, the method should re-arrange the contents of the ArrayList so that it contains the values 3 2 1.
As you implement each method, be sure to comment out
throw new UnsupportedOperationException(“TODO - implement”);
Hints
- declare an array reference and allocate a new array in readArray using the numElements parameter value, then return the reference after loading in the values.
- to reverse the array (note you should not allocate a new one) consider creating a loop that swaps the first and last elements, second and next to last, etc. Alternatively, create a new temporary array and copy the elements from the original to the temporary in reverse order and then back to the original.
- declare an ArrayList<Integer> reference and allocate a new ArrayList (which will be empty) in readArrayList (note you do not need to use the numElements parameter value to create it). Then use the numElements parameter to control a loop that uses the ArrayList object’s add method to insert the values, and return the reference to the ArrayList.
- to reverse the ArrayList, use a similar procedure to the array only with the get method to read a value and the set method to change a value at a given index. (Or look at the API for ArrayList to see if there are any methods that can do it for you - “find an object, call a method”).
Testing
In src/test/java/(default package) right-click on the appropriate test class and choose Run As…→JUnit Test. This will run the JUnit tests for the corresponding class. If you have correctly implemented the class, you will see a green bar, indicating that all tests have succeeded.
Running
A main method is provided which you should not change.
Run the program by right-clicking on the file ArrayAndArrayList.java in the src/main/java/(default package) package, and then choosing
Run As→Java Application
When you run the main method, you should see output looking something like this (user input in bold):
Select: 1 Array 2 ArrayList 0 Quit 1 How many values? 5 Please enter 5 values: 9 0 1 2 5 You entered the following values: 9 0 1 2 5 Now I am going to reverse the array for you... Here are the reversed array values: 5 2 1 0 9 Select: 1 Array 2 ArrayList 0 Quit 2 How many values? 4 Please enter 5 values: 8 6 7 5 You entered the following values: 8 6 7 5 Now I am going to reverse the ArrayList for you... Here are the reversed ArrayList values: 5 7 6 8 Select: 1 Array 2 ArrayList 0 Quit 0 Goodbye
Submitting
When you are done, submit the lab to the Marmoset server using either of the methods below.
From Eclipse
If you have the Simple Marmoset Uploader Plugin installed, then right click on the project (CS201_Lab04_Gradle) and choose Submit project…. Enter your Marmoset username and password when prompted.
From a web browser
Save the project (CS201_Lab04_Gradle) to a zip file by right-clicking it and choosing
Export…→Archive File
Upload the saved zip file to the Marmoset server as lab04. The server URL is
