Today's exercise involves a series of experiments, each investigating a different aspect of a fundamental Java concept: the expression. The term expression can be defined as follows:
An expression is a sequence of one or more operands, and zero or more operators, that when combined, produce a value.
To illustrate, the sequence
fits the definition of an expression, since it consists of one operand (12) and zero operators that combine to produce a value (12). Perhaps more familiarly, the sequence
2 + 3
fits the definition of an expression, since it consists of two operands (2 and 3) and one operator (+) that combine to produce a value (5). Operands need not be constants: the sequence
2.5 * x - 1.0
fits the definition of an expression, since it consists of three operands (2.5, x and 1.0) and two operators (*, -) that combine to produce a value (1 less than the product of 2.5 and x).
These last two examples have been arithmetic expressions, that is, expressions whose operators are familiar arithmetic operators. As we shall see in today's exercise, Java provides a rich set of both arithmetic and non-arithmetic operators that allow Java programmers to construct expressions.
Using what you have learned previously, begin by creating an Express project as appropriate for your environment.
We will use the file Express.java as a software laboratory for most of the experiments in this exercise. Click on the preceding link, and use your browser's
File -> Save As
menu choice to save this file in your Express project directory. Add Express.java to your project if needed. You can then open the file and take a moment to study its contents.
In our print() and println() statements, we have expressions of the form
Expression1 + Expression2 + ... + ExpressionN;
where some of the expressions are characters or strings. The exact details are fairly complicated, but the net effect is that Expression1 is evaluated and displayed, after which Expression2 is evaluated and displayed, after which ..., after which ExpressionN is evaluated and displayed. An output statement thus provides a simple "laboratory" in which we can "experiment" with expressions by building them and viewing the values they produce. Note that the parentheses around the i + j are required if we actually want to print the sum of i and j and not the value of i followed by the value of j.
Below is a list of the experiments available for this exercise. Your instructor will tell you which ones you can omit, if any.
For each experiment that you are to perform, click its link and print a hard copy of the resulting web page. Then record your experimental results on that hard copy.
Experiment 1: Simple Expressions
Experiment 2: Characters and Character Strings
Experiment 3: Arithmetic Expressions
Experiment 4: Relational Expressions
Experiment 5: Logical Expressions
Experiment 6: Operator Precedence
Experiment 7: Operator Associativity
Experiment 8: Expressions Containing Functions
Experiment 9: Declarations
Experiment 10: Constant Declarations
Experiment 11: Assignment Statements
Experiment 12: Assignment Associativity
Experiment 13: Assignment Shortcuts
Experiment 14: Increment and Decrement Expressions
Expression, Simple Expression, Operand, Operator, Operator Precedence, Operator Associativity, Integer Division, Logical Operator, Boolean Operator, Libraries of Methods, Variable Declaration, Constant Declaration, Operator Chaining, Increment Expression, Decrement Expression.
Turn in to your instructor the hard copies showing the results of each of your experiments, plus a hard copy of your final version of Express.java.
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