Introduction

In this tutorial, we will explore how to control the flow of execution in a Java program using 'if', 'else', and 'switch' statements. These elements are crucial for developing dynamic programs that can execute different actions based on various conditions.

You will learn:
- How to use 'if', 'else', and 'switch' statements
- How to write efficient and effective conditional statements
- Best practices when dealing with control flow statements

Prerequisites:
- Basic knowledge of Java syntax and programming concepts
- A Java development environment set up on your machine

Step-by-Step Guide

If Statement

The 'if' statement is the simplest form of control flow statement. It is used to decide whether a certain statement or block of statements will be executed or not i.e. if a certain condition is true then a block of statement is executed otherwise not.

if (condition) {
  // code to be executed if condition is true
}

Else Statement

An 'else' statement can be combined with an 'if' statement. An 'else' statement contains the block of code that will be executed if the associated 'if' statement's condition is false.

if (condition) {
  // code to be executed if condition is true
} else {
  // code to be executed if condition is false
}

Switch Statement

A 'switch' statement allows a variable to be tested for equality against a list of values. Each value is called a case, and the variable being switched on is checked for each case.

switch(expression) {
  case value1 :
    // code to be executed if expression equals value1
    break; // optional
  case value2 :
    // code to be executed if expression equals value2
    break; // optional
  // You can have any number of case statements.
  default : // Optional
    // code to be executed if expression doesn't match any case
}

Code Examples

If-Else Statement

int number = 10;
if (number > 0) {
  System.out.println("Number is positive.");
} else {
  System.out.println("Number is not positive.");
}

In this example, the program checks if the number is positive. If the number is greater than 0, it prints "Number is positive." If not, it prints "Number is not positive."

Switch Statement

int day = 2;
String dayString;
switch (day) {
  case 1:  dayString = "Monday";
           break;
  case 2:  dayString = "Tuesday";
           break;
  // ... // other days
  default: dayString = "Invalid day";
           break;
}
System.out.println(dayString); // Prints "Tuesday"

This example assigns a different string to the dayString variable depending on the value of the day variable.

Summary

In this tutorial, you have learned how to control the execution flow of your Java programs using 'if', 'else', and 'switch' statements. These control flow statements are a fundamental part of Java and many other programming languages.

Next, you might want to learn about loops in Java, which are another crucial part of controlling program flow.

Practice Exercises

1. Write a Java program that takes a single digit number and prints the number in word using switch statement. (Difficulty: Easy)

2. Write a Java program that takes a grade (A-F) and prints excellent, good, fair, poor based on the grade using if-else statements. (Difficulty: Medium)

3. Write a Java program that simulates a basic calculator using switch statement. (Difficulty: Hard)

Solutions and explanations will be provided upon request. As a best practice, try to solve the problems by yourself before looking at the solutions. Happy coding!