Week 15

Project presentations, exam review.

Exam review

The exam is comprehensive – see also review for first exam, from week 7. You’ll have to use more methods/functions than last time. I’ll include a list of all methods you might need, but remember you can also bring 1 sheet of paper with notes.

Key concepts (in addition to concepts covered on midterm):

Defining and using functions
Using objects in Java, especially Strings
Arrays: 1- and 2-dimensional
Input and output. You won’t have to memorize specific classes to use, but you should be able to recognize what’s going on.
Error handling. Recognize how exceptions are handled.
Basic object-oriented programming. Know what an instance variable and instance method are, and how they’re different from static methods.

Example problems:

Define a function called rep that takes a String s and an integer n as input and prints s repeated n times. Example: rep("x", 5) prints xxxxx.
Define a function that takes an array of integers as input and returns the second largest value in the array.
Define a function that takes an array of Strings as input and returns the longest.
Define a function that takes two Strings as input and returns the number of characters where they match.
Define a function that takes a 2-dimensional array of integers as input, and returns the average of all entries.
Define a function that takes a 2-dimensional array of integers as input, and returns an array containing the average of each input row.
Design a class that represents a triangle. What instance variables do you need? What should you check when creating a Triangle object to make sure the input is valid?
Consider the following class:
```
public class Point {
    final int x;
    final int y;
    public Point(int x, int y) {
        this.x = x;
        this.y = y;
    }
}
```
Define a method that takes integers xOffset and yOffset and returns a new Point that is shifted from the original by the given values.
Design a class that represents a gun, including keeping track of how many bullets the gun has left. Include a method called shoot that fires the gun.

What is the output of the following program?

  int[] a = {0,1,2,3,4};
  try { 
      System.out.println(a[5]);
  } catch (IndexOutOfBoundsException e) {
      System.out.println("Bad array index");
  }
  try {
      System.out.println(a[1]);
  } catch (IndexOutOfBoundsException e) {
      System.out.println("Bad array index");
  }

What is the output of the following program?

  int[][] a = {
      {1, 2, 3},
      {4, 5, 6}
  };
  for (int[] row : a) {
      for (int entry: row) {
          if (entry % 2 == 0)
              System.out.print("even ");
          else
              System.out.print("odd  ");
      }
      System.out.println();
  }

Write a program that uses a Scanner object to read in 10 integers and print them in reverse order of how they were read in (meaning printing the last integer read in first).
Write a program that uses a Scanner object to read in 10 integers and prints only the integers that are multiples of 5.
Write a program that uses a Scanner object to read in 10 integers and prints the product of the odd integers.

Reading

Java for Everyone, review chapters 1-8.

Homework

Finish your project! Email to me before next class.
Study for next week’s final exam.

CSC 130, Spring 2011

Week 15

Exam review

Example problems:

Reading

Homework

Pages: