9/24/2018 Programming Data Structures

Transcription

1 9/24/2018 Programming Data Structures Polymorphism Debug Advanced-Techniques/ html 1

2 Quiz on next Monday, Oct. 1 Questions are from: All the slides from 9/5 to 9/24 All the assignments from 9/5 to 9/24 Topics include 2-dimensional arrays, encapsulation, inheritance, packages, polymorphism, abstract classes. Open-book 30 min 2

3 Github Repo Link <to fill> 3

4 Assignments Review Download Person.java and Student.java from the Github repository. Run the main method from Student.java, and you will find the console output is: 4

5 Debugging in bluej Mouse click on the left white-margin of a specific line, and you will see a breakpoint (in red) 5

6 Debugging in bluej Then, you can run the program with the breakpoint 6

7 Debugging in bluej Debugger Window Call Sequence Variables 7

8 Currently, the next statement to be executed is the green line 8

9 Debugging in bluej Click Step Into to step into the method: 9

10 Debugging in bluej Call Sequence Variables 10

11 Debugging in bluej The next statement to be executed is the green line 11

12 Debugging in IntelliJ/Eclipse Mouse click on the left white-margin of a specific line, and you will see a breakpoint (in red) 12

13 Debugging in IntelliJ/Eclipse Run the main method with Debug command 13

14 Debugging in IntelliJ/Eclipse Near the bottom of the IDE, you can find a Debugger window 14

15 Debugging in IntelliJ/Eclipse Call sequences Variables 15

16 Debugging in Intellij/Eclipse Step into the method 16

17 Debugging in Intellij/Eclipse The next statement to be executed is highlighted. 17

18 There are two bugs in Person and Student Find the bugs and fix them 18

19 Critters and Ants and Doodlebugs and the World... Display the World: 19

20 Critters and Ants and Doodlebugs and the World... Display a node: 20

21 Critters and Ants and Doodlebugs and the World... Another way??? Create a project using your assignment04 code OR download the Critter.java, Ant.java, Doodlebug.java, World.java in the Github repo 21

22 Critters and Ants and Doodlebugs and the World... Try to change the method: Display in World.java Hint: Add display methods in Ant, Doodlebug, and Critter. 22

23 Update the display method Before, for each ant, we print x ; for each doodlebug, we print o ; for each empty cell, we print. To achieve a more straightforward display, we change the rule to: for each ant, we print A for each doodlebug, we print D for each empty cell, we print. 23

24 Critters and Ants and Doodlebugs and the World... Review the last take-home assignment Put (assign) critters to the World (randomly) How to pick a random location from Critter[][] grid Pick a random row index and pick a random column index. And we have a random cell: 24

25 Critters and Ants and Doodlebugs and the World... Review the last take-home assignment How to create a random number in a range 0 N: Method 1: In the beginning of the java file, you need to import the Random package: Then, you use Random like the following lines: Method 2: 25

26 Critters and Ants and Doodlebugs and the World... Review the last take-home assignment Put (assign) critters to the World (randomly) How to pick a random location from Critter[][] grid Pick a random row index and pick a random column index. And we have a random cell: 26

27 Critters and Ants and Doodlebugs and the World... Review the last take-home assignment Put (assign) critters to the World The first try: 27

28 Critters and Ants and Doodlebugs and the World... Review the last take-home assignment Put (assign) critters to the World One way to assign an Ant to a cell: 28

29 Critters and Ants and Doodlebugs and the World... Review the last take-home assignment Put (assign) critters to the World The second way to assign an Ant to a cell: 29

30 Critters and Ants and Doodlebugs and the World... Review the last take-home assignment Put (assign) critters to the World The third way to assign an Ant to a cell: 30

31 Practice debugging and assigncritters 1. In your World.java, try to implement an AssignCritters in a different way than your last submission 2. Use the following main method (in World.java) to test your new AssignCritters 31

32 Practice debugging and assigncritters 3. Use the debugger described in slides 3 15 to record the values of the random numbers for each iteration in your loop 32

33 How to make Ant move to the cell below Suppose a critter has its own location: 1. World 2. (x, y) For each ant: 1. Check whether the cell below is available 1) If the cell below is available (the cell is not out of boundary and is empty), put the ant to the next cell 2) Else: the ant does not move 33

34 Add location variables to Critter 34

35 Because we changed the base class, Critter, we have errors in the derived classes, Ant and Doodlebug Update Doodlebug and Ant. 35

36 Remove the print statement in the move method in Doodlebug 36

37 Update World class to access the cell in the grid 37

38 Update World class to move all the ants at once 38

39 Update the move method in Ant In class assignment (1 point) 1. For each ant: Check whether the cell below is available 1) If the cell below is available (the cell is not out of boundary and is empty), put the ant to the next cell 2) Else: the ant does not move 39

40 In-class assignment debug the main method (1 point) record the values of the ant variables in the grid when onestepsimulation is called (debug main method in Main.java) Write the values down in a text file, and add the text file to the Github Repository. 40