CS141: Topics for Week 8: Oct 16 & 18, 2017

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Mid-Semester Day

No classes or labs on Friday due to mid-semester day. Enjoy!

Mon: Continue from Last Week

• Finish discussion of Loops

Reading:

• Chp 7: Arrays and ArrayLists

Lab and Other Activities

• Lab 7: Arrays
• Practice Array problems. Try them on your own. If you can't seem to figure a problem out, look up the solution here.

• Object Diagram Practice: Assume there is a Card class defined. Draw the object diagram after each line is executed:

  Line  0:   public static void main(String[] args) {
  Line  1:      Card[] myCards;
  Line  2:      myCards = new Card[4];
  Line  3:      for (int i = 0; i < myCards.length ; i++) {
  Line  4:         myCards[i] = new Card(i);  
  Line  5:         System.out.print(myCards[i] + " "); 
  Line  6:      }
  Line  7:      Card c = myCards[3];
  Line  8:      myCards[0] = myCards[1];
  Line  9:      myCards[2] = null;
  Line 10:      myCards[3] = null;
  Line 11:      myCards[3] = c;
  Line 12:      System.out.println("\n");
  Line 13:      for (int i = 0; i < myCards.length ; i++) {
  Line 14:         System.out.print(myCards[i] + " "); 
  Line 15:      }
  Line 16:   }

  Assuming that the output from Line 5 gives the A♠, 2♠ 3♠ 4♠, what is the output at Line 14?
  Solution may be found here: Lines 1-7 and Lines 8-16

Lecture Discussion Topics:

• What is an array? Why do we need them?
• Declaring 1-dimensional arrays. (Here are some old notes on 1D Arrays.)
• Accessing array elements
• Initializing arrays
  • one at a time.
  • Using for-loop
  • Using brackets
  • Using Arrays class.
  • Reading from a file. (we'll do this next week)
• Printing or Using arrays
  • one at a time.
  • Using for-loop
  • Using an enhanced loop
  • Using Arrays class.
• Array of primitives vs array of object/references
• Swapping elements in an array.
• Copying arrays.
• Comparing arrays.
• Partially filled arrays
• Accumulating values in an array.
• Arrays as return values and parameters in methods. Arrays are passed by reference. Recall Pass by Value vs Pass by Reference (pdf)
• Sorting using Selection Sort
• Binary search
• ArrayLists: declaring, adding/removing elements, look at method list, copying, wrappers for primitive types
• Declaring multi-dimensional arrays. (Here are some old notes on 2D Arrays.)
  • Examples: Mazes, Game of Life, TicTacToe

Concepts and Vocabulary

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