Java Basics: Exploring Primitive Data Types and Strings

In Java, we use numerical data types to represent numbers. Specifically, in this lesson, we're focusing on int and float. The int data type is used to represent whole integer numbers, and the float data type is used to represent decimal numbers - numbers with a decimal point.

The largest value an int can store is 2147483647, which is $2^{31} - 1$, and the smallest is -2147483648, which is $-2^{31}$. Here's an example of using the int number:

int daysInWeek = 7;
System.out.println(daysInWeek);  // This will print: 7

int maximalInteger = 2147483647;
System.out.println(maximalInteger);  // This will print: 2147483647

int tooBigInteger = 2147483648; // Oops! Error, the number is too large

Now, let's move on to the float data type. float is used when dealing with numbers that have decimal points, also known as floating-point numbers. A float can hold up to 7 decimal digits of precision. Consider the following example:

float pi = 3.1415926f;
System.out.println(pi);  // This will print: 3.1415926

Ensure that the f at the end of the number is present; it differentiates a float from a double - another type for decimal numbers, with higher precision.

Now, let's move on to the boolean and char data types.

The boolean data type in Java can hold one of two possible values: true or false. This data type is widely used in logical expressions and decision-making. Here's a simple example:

boolean isEarthRound = true;
System.out.println(isEarthRound);  // This will print: true

boolean isEarthFlat = false;
System.out.println(isEarthFlat); // This will print: false

The char data type is used to store a single character. Java uses Unicode, allowing a char to store any character! Here's how it's done:

char firstLetterOfAlphabet = 'A'; // A character is always surrounded by single quotes
System.out.println(firstLetterOfAlphabet); // This will print: A

You'll find that String is as common in Java as stars in the cosmos. Java treats String as a basic data type and uses it to store a sequence of characters - just a text. The string is always surrounded by double quotes.

String welcome = "Welcome to Java!";
System.out.println(welcome); // This will print: Welcome to Java!

What's interesting to note is the immutability of String in Java. Once a String is created, its value can't be changed.