float

A float represents decimal (floating-point) numbers in Java

• It uses 32 bits (4 bytes) of memory
• It can store values approximately in the range: 1.4E-45 to 3.4028235E38

This makes float useful when you need decimal numbers but want to save memory.

Declaring and using float

By default, Java treats decimal numbers as double. Adding F (or f) tells Java: “This number is a float.”

float count = 20.1F;       // Must end with F or f
float temperature = -9.5F;

float vs double

Java has two decimal types:

Note: Use double unless you specifically need float

Primitive type

float is a primitive data type.

• It stores its actual value directly in memory
• It does not store a reference to an object
• It has no methods

Changing float values

Primitive types have no internal state. Primitive types have no internal state.

float a = 15.2F;
a = 20.7F;   // 15.2F is replaced by 20.7F

Wrapper class: Float

Even though float itself has no methods, Java provides the Float wrapper class. This allows you to:

• Convert values
• Compare floats safely
• Access constants like max/min values

Useful Float constants

Converting values

Converting numeric String to float. If the string is not numeric (e.g. "hello"), Java throws a
NumberFormatException.

float num = Float.parseFloat("123.5"); // Returns 123.5

Converting a float to a String

String text = Float.toString(42.5F); // Returns "42.5"

Comparing Float values

compare(float a, float b)

int result = Float.compare(1.5F, 2.5F);

compareTo(Float other)

Float x = 10.0F;
Float y = 12.2F;

x.compareTo(y);

Both compare and compareTo return these values:

• 0 → if values are equal
• -1 → if first is less than second
• 1 → first is greater than second

equals(Object obj)

Float x = 10.0F;
Float y = 10.0F;

x.equals(y); // true

Math helper methods

Summary

• float stores decimal numbers using 4 bytes
• Must use F when assigning values
• It’s a primitive type
• Use Float wrapper class methods for conversions, comparisons, and constants
• Prefer double unless you need float

Further Reading

• Java Float class
• Java primitives