Types in Depth

Types in Depth

In this lesson — part of Data Deep Dive — you'll learn types in depth in Java and why it matters in real work.

Why it matters

Types tell you what operations make sense and catch whole classes of bugs early.

Key ideas

• Common types: text, numbers, booleans
• Type conversion and coercion
• When to be explicit about types
• Type errors and how to read them

In practice

Here's how it looks in idiomatic Java:

int i = 42;
double d = i;            // widening: int -> double, implicit
int back = (int) 3.99;   // narrowing needs an explicit cast (truncates to 3)
String text = Integer.toString(i); // boxing/parsing via wrapper classes
System.out.println(d + ", " + back + ", " + text);

Java note: Widening conversions are implicit but narrowing ones require an explicit cast, and converting to/from String goes through wrapper-class methods like Integer.toString/Integer.parseInt.

Try it yourself

Exercise: In Java, convert a number to text and back, and print both.

Recap

You now understand types in depth and can apply it in Java. Mark this lesson complete and continue to the next one.