Untitled Quiz

Identifiers, Keywords, and Literals in Java

• Identifiers are names created by programmers to identify variables, methods, classes, or other entities.
• Valid identifiers can include uppercase and lowercase letters, digits (0-9), underscores (_), and dollar signs ($).
• Identifiers must start with a letter, underscore, or dollar sign. Cannot start with a digit.
• Reserved keywords, which have special meanings in Java, cannot be used as identifiers.
• Java identifiers are case-sensitive; for example, myVariable and myvariable represent different identifiers.

Primitive Data Types in Java

• Java has several primitive data types including int, char, double, boolean, etc.
• Primitive types represent single values and are not objects.
• Automatic type conversion occurs when a value of a smaller data type is converted to a larger data type automatically by Java (e.g., int to double).
• Explicit type conversion (casting) requires manual specification; for example, converting a double to an int using (int) myDouble.

Operators in Java

• Relational Operators

  • == (Equal to): Returns true if two values are equal.
  • != (Not equal to): Returns true if two values are not equal.
  • > (Greater than): Returns true if the left value exceeds the right value.
  • >= (Greater than or equal to): Returns true if the left value is greater than or equal to the right value.

• Logical Operators

  • && (Logical AND): True if both operands are true.
  • || (Logical OR): True if at least one operand is true.
  • ! (Logical NOT): Reverses the logical state of its operand.

• Operator Precedence

  • Operator precedence determines the order of evaluation in expressions. Higher precedence operators are evaluated first.
  • Parentheses can be used to explicitly dictate the order of evaluation regardless of default precedence rules.

Control Flow with Switch Statements

• Usage: Switch statements allow selecting one of many code blocks for execution.
• Conditions: They evaluate a single expression against multiple cases.
• Data Types: Switch works with int, char, String, and enumeration types.
• Efficiency: Typically more efficient for evaluating multiple discrete values than if-else chains.