CMPS 134
Preview for Test #1

Among the things that you should know:

• Java is the programming language that we are using in this course as a vehicle to learn about computer programming.
• jGrasp is the "integrated development environment" (IDE) that we are using (at least in lectures) to aid us in developing and testing Java code.
• Among the kinds of errors that can be present in computer programs are syntax, logical, and run-time. Syntax errors, which are detected by the Java compiler, are analogous to errors in English grammar. A run-time error occurs when a program's execution is aborted due to an unexpected condition occurring (e.g., invalid input (such as a real number or a string of characters when an integer was expected)), division by zero). A logical error is caused by a programmer making a mistake that results in a program that, when executed, behaves in a way that was not intended. For example, the program could produce output that is not correct with respect to its input. Run-time errors are often the result of an underlying logical error.
• Comments appear in programs to provide useful information to human readers. Among the kinds of information that comments might convey are
  • the program's intended behavior/purpose
  • the author(s) (i.e., who developed the code)
  • the date(s) on which the program was modified
  • an explanation of the reasoning that justifies certain code segments being written as they were
• Java has eight primitive data types. Among them are the four that are most imporant in this course: int (for representing integers (e.g., 13)), double (for representing real numbers (e.g., 27.35)), boolean (for representing true and false), and char (for representing character values (e.g., 'W')).
• How to evaluate arithmetic and boolean expressions involving literals (e.g., 32, 1.52, true), variables, arithmetic operators (+, -, *, /, %), relational operators (<, <=, >, >=, ==, !=), and boolean operators (!, &&, ||).

  Examples (where k, m, x, etc., are variables whose data types and values would be indicated on the test):

  5 + k * 8	k / 4	(k+3) % m	5 * 2.5
  (char)('A' + 4)	(double)(k - 2)	Math.abs(k)	(3 * k) / m * x

• How to evaluate expressions involving calls to methods in the java.lang.String class. Examples (where s and t are variables of type String and k and m are of type int, all having values indicated on the test):

  s.charAt(k+2)	s.substring(k,m)	(s+t).length()
  s + t.substring(k)	s.indexOf('A')	s.substring(s.indexOf(','), s.lastIndexOf(' '))

• You should be able to "trace execution" of a Java program involving variable declarations, assignment statements, methods, calls to methods (possibly with parameters being passed and/or values being returned by the method), and for-loops. For example, you may be given a Java program and asked to show what output it would produce if it were executed.
• Given a Java program, you should be able to identify pieces of it that are examples of the following elements of the Java language:
  • key/reserved word (e.g., class, int, public)
  • comment (e.g., /* This program does nothing. */)
  • assignment statement (e.g., x = 3.5 or grossPay = hoursWorked * hourlyWage)
  • numeric literal (e.g., 3.5 in line above)
  • String literal (e.g., "Hello, World!")
  • variable declaration (e.g., int numHours)
  • method call (e.g., drawRightTriangle(k+1))
  • actual parameter/argument (e.g., the k+1 in line above)
  • method heading (e.g., public static void drawRightTriangle(int size))
  • formal parameter/argument declaration (e.g., int size in line above)
  • class heading (e.g., public class Stupid)
• Given a simple computational task that can be accomplished using assignment statements, arithmetic or boolean expressions, calls to methods in the java.lang.Math class, and possibly a for-loop, you should be able to write Java code (perhaps a method body) that performs it. Examples:
  • Given a number of inches, express it in terms of feet and inches.
  • Print each even integer in the range 4..51.
  • Print the sum of the odd integers in the range 0..13.
  • Print the sum of the square roots of the integers in the range 0..13.
  • "Draw" a figure similar to ones drawn by the DrawFiguresWithLoops application program.