Question

Fill in the blanks in each of the following statements: a) Typically, ________ statements are used for counter-controlled repetition and _________ statements are used for sentinel-controlled repetition. b) The do…while statement tests the loop-continuation condition __________ executing the loop’s body; therefore, the body always executes at least once. c) The __________ statement selects among multiple actions based on the possible values of an integer variable or expression. d) The __________ statement, when executed in a repetition statement, skips the remaining statements in the loop body and proceeds with the next iteration of the loop. e) The __________ operator can be used to ensure that two conditions are both true before choosing a certain path of execution. f) If the loop-continuation condition in a for header is initially ___________ , the program does not execute the for statement’s body. g) Methods that perform common tasks and do not require objects are called _____________ methods.

Short answer

Counter-controlled uses `for`, sentinel uses `while`; `do…while` tests after execution; `switch` selects multiple actions; `continue` skips to next loop iteration; `&&` is used for dual condition truth; `false` skips `for` loop body; `static` methods do not require objects.

Step-by-step solution

Identifying control statements

Counter-controlled repetition is typically handled by `for` statements because they are specifically designed to iterate a known number of times. Sentinel-controlled repetition is commonly managed using `while` statements since the number of iterations is not predetermined.

Understanding do...while statement

The `do...while` statement checks the loop continuation condition after executing the loop's body, ensuring that the loop executes at least once.

Selecting among multiple actions

The `switch` statement selects among multiple actions based on the possible values of an integer or enumerated variable, streamlining decision-making over multiple potential scenarios.

Skipping remaining statements in a loop

In repetition statements, the `continue` statement is used to skip the remainder of the loop's body and proceed directly to the next iteration of the loop.

Ensuring dual condition truth

The `&&` (logical AND) operator is utilized in conditional statements to verify that two conditions are true before a certain path is executed.

Checking initial loop conditions

If the continuation condition in a `for` loop header is initially `false`, the loop's body does not execute, preventing unnecessary iterations.

Defining common tasks without objects

Methods that perform common tasks but do not require specific object instances are called `static` methods. They are defined in classes and accessed in a class-wide context.

Key concepts

Control Statements

Control statements in Java allow programs to choose different actions based on conditions or scenarios. They are the backbone of decision-making and flow control in programming. The most common types are the `if`, `switch`, and loop statements.

• `for` statement: Ideal for counter-controlled repetition, it is used when you know the number of times you need to execute a block of code. Commonly used in scenarios where a fixed number of iterations is needed. For example, iterating over an array with known size.
• `while` statement: Suited for sentinel-controlled repetition, where the loop continues until a certain condition is no longer true. The number of iterations is not predetermined.
• `do...while` statement: Similar to the `while` loop but ensures the loop executes at least once, as the condition is checked after the loop's body runs.

These statements enable programmers to control the behavior of the program dependently on dynamic conditions.

Loop Structures

Loop structures are crucial for executing a set of instructions repeatedly. In Java, these structures include `for`, `while`, and `do...while` loops.

• `for` loop: Best used when the number of iterations is known beforehand. It includes initialization, condition-checking, and increment/decrement in one line.
• `while` loop: Executes as long as the condition is true, making it suitable for situations where the loop's continuation depends on a dynamic condition rather than a fixed count.
• `do...while` loop: Guarantees that the code block runs at least once. This is useful when the initial execution of the loop's body is required to potentially influence the loop's condition.

Loops are fundamental in programming to perform repetitive tasks efficiently while maintaining clear and manageable code.

Conditional Statements

Conditional statements allow Java programs to execute code blocks based on specific conditions. The primary conditional statements are `if`, `else if`, and `switch`.

• `if` statement: Executes a block of code if a specified condition is true. Enables decisions with simple conditions.
• `else if` and `else` statements: Extend the `if` statement to handle additional conditions. Provides multiple action paths depending on different conditions.
• `switch` statement: Simplifies coding when there are multiple values to evaluate from a single integer or enumerated type expression. It directs the program to the code block associated with a matching value.

The `&&` (logical AND) operator is often used in these statements to ensure that multiple conditions are met. This logical operator checks that both statements are true before continuing with the chosen execution path. These constructs are pivotal in forming the decision-making logic in Java applications.