CMSC 131 Object Oriented Programming I Midterm Exam 1 March 3 2004 Grader Use Only Name Problem 1 20 points General Questions a What is the name of the IDE you have been using for this class b Is a parameter an instance variable Answer Yes or No c Which of the following are valid names for Java variables Circle valid variable names 10 dog 77temperature abc15 d Is RAM classified as main or secondary memory e Are hard disks volatile or non volatile memory f Are all reference variables local variables Yes or No 1 a b c d e f g h i j 1 subtotal 2 a b c d 2 subtotal 3 4 a b 4 subtotal Total 2 2 2 2 2 2 2 2 2 2 20 6 6 6 11 29 27 12 12 24 100 g What is the name of the entity within the Java Virtual machine that is responsible for collecting objects that have no more reference variables that reference them h Can we declare two instance variables with the same name in a class Yes or No i Are instance variables initialized to a default value Yes or No j Which of the following are valid primitive types in Java Circle valid types int boolean float scientific Problem 2 29 points Understanding Code This problem refers to the code on the next page You can assume that the Weather class is stored in a file named Weather java and the ProbTwo class is stored in a file named ProbTwo java public class Weather private double humidity public Weather double theHumidity humidity theHumidity public void setHumidity double theHumidity humidity theHumidity public double getHumidity return humidity public class ProbTwo public void one int x int y System out println x y System out println x y System out println x y System out println x y 5 System out println x y public void two double f double g double k if f g f 0 0 if g k false System out println Case 1 else System out println Case 2 else System out println Case 3 public void three int b int i 1 while i b if i 2 i i 1 System out println i i i 1 System out println i public void four Weather mon Weather fri double maxTemp mon new Weather 100 00 fri setHumidity 90 fri setHumidity 70 maxTemp 110 Draw the memory diagram when code execution reaches this point a 6 points What is the output produced by executing the following code segment ProbTwo prob2 new ProbTwo prob2 one 8 4 b 6 points What is the output produced by executing the following code segment ProbTwo prob2 new ProbTwo prob2 two 5 0 10 0 7 0 prob2 two 5 0 8 0 9 0 c 6 points What is the the output produced by executing the following code segment ProbTwo prob2 new ProbTwo prob2 three 3 d 11 points For this part you will draw a memory diagram The following is a memory diagram example int a 10 String m new String Hello 10 a Hello m Draw a memory diagram that represents the state of the variables monday friday maximum mon fri maxTemp and all objects after the following code segment has been executed but just before the four method returns that is we want to see the values of the local variables within four before it exits Weather monday new Weather 80 0 Weather friday new Weather 60 0 double maximum 120 prob2 four monday friday maximum Problem 3 27 points Class Implementation Write the complete code for a class named TwoStripes similar to Stripes from the homework that implements a picture with two vertical stripes each having a particular color Each strip should have the same width and the two stripes should fill the picture You can assume the specified width of the picture is even The constructor has the following signature public TwoStripes int width int height PictureColor firstStripe PictureColor secondStripe Your class must implement the following interface public interface Picture public PictureColor getColor int x int y public int getWidth public int getHeight You may use one character variable names but you must have good indentation Problem 4 24 points Syntax Errors Circle the pieces of code that have syntax i e compiler errors in each of the following code segments a 12 points There are 6 syntax errors in this code segment public class private area private boolean int poblic void f2 int x y if x 3 System out println Step 1 else System out println Step 2 A simple method public void setArea theArea double area theArea b 12 points There are 3 syntax errors in this code segment public class ProbThreeC private int numBananas private double gallonsCoffee public void test boolean likesMe numBananas gallonsCoffee gallonsCoffee numBananas gallonsCoffee likesMe if numBananas gallonsCoffee System out println hello int a 0 if a 2 3 System out println hello if a 2 3 System out println hello
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