Understanding Java Fundamentals
To grasp the basics of Java, it’s essential to understand expressions, statements, and blocks. Now that you’re familiar with variables, operators, and literals, let’s dive into these concepts.
What are Java Expressions?
A Java expression is a combination of variables, operators, literals, and method calls that evaluate to a value. For instance, score = 90 is an expression that returns an integer value. Similarly, a + b - 3.4 is an expression that performs arithmetic operations, and "Number 1 is larger than number 2" is a string expression. Method calls are also expressions, which we’ll explore in more detail later.
Java Statements: The Building Blocks of Code
In Java, each statement is a self-contained unit of execution. Consider the example score = 9 * 5;. This statement multiplies two integers and assigns the result to the variable score. Here, 9 * 5 is an expression that’s part of a larger statement. Statements can be thought of as the individual steps that a program takes to accomplish a task.
Expression Statements: Converting Expressions to Statements
You can convert an expression into a statement by adding a semicolon at the end. These are known as expression statements. For example, number = 10; is an expression statement, where number = 10 is the expression, and the semicolon makes it a complete statement. Similarly, ++number; is a statement, whereas ++number is just an expression.
Declaration Statements: Defining Variables
In Java, declaration statements are used to declare variables. For instance, double tax = 9.5; declares a variable tax and initializes it to 9.5.
Java Blocks: Grouping Statements Together
A block is a collection of statements (zero or more) enclosed in curly braces {}. Blocks are useful for organizing code and controlling the flow of execution. Consider the example:
if (true) {
System.out.print("Hey ");
System.out.print("Jude!");
}
Here, the block contains two statements that print “Hey Jude!” to the console. However, a block can also be empty, as shown in the following examples:
if (true) {}
public static void main() {}
These blocks don’t contain any statements but are still valid Java code.
Now that you’ve learned about Java expressions, statements, and blocks, you’re better equipped to write efficient and effective code. Remember to practice and experiment with these concepts to solidify your understanding.