Java offers two primary data types for representing floating-point numbers: double and float. But what exactly are they, and when do we need to convert between them? This article will guide us through these data types, explore conversion methods, and discuss how to convert between float number values and double number values in Java.
1. Understanding Doubles and Floats
Doubles and floats are used to represent decimal values in Java, However, doubles offer more precise decimal representation, while floats are more memory-efficient.
1.1 Double
A double-precision floating-point number offers a wider range and higher precision compared to a float. The Double class provides static final members that represent the minimum and maximum values a double can hold. It can store values between approximately -1.7976931348623157E+308 and 1.7976931348623157E+308. Here’s how we can access this information:
System.out.println("Minimum value for double: " + Double.MIN_VALUE);
System.out.println("Maximum value for double: " + Double.MAX_VALUE);
This will print something like:
Minimum value for double: 4.9E-324 Maximum value for double: 1.7976931348623157E308
1.1.1 Declaring a double in Java
To declare a double in Java, we specify the type as double, provide a variable name and assign a value within the range of a double.
Example:
double someDouble = 3.141592653589793;
1.2 Float
A single-precision floating-point number provides a smaller range and lower precision than a double. The Float class also offers two static final members, MIN_VALUE and MAX_VALUE, that represent the minimum and maximum values that a float can hold. It can store values between approximately -3.4028234663852886E+38 and 3.4028234663852886E+38. Here’s how we can access this information:
System.out.println("Minimum value for double: " + Double.MIN_VALUE);
System.out.println("Maximum value for double: " + Double.MAX_VALUE);
1.2.1 Declaring a float in Java
To declare a float in Java, specify the type as float, provide a variable name, assign a value within the range of a float and append the letter f after the last number.
Example:
float someFloat = 3.14159f;
Pay attention to the ‘f’ suffix appended to the float values.
2. Converting Between Doubles and Floats
We’ll explore two techniques for converting between double and float data types in Java—Type Casting and using Class methods.
2.1 Type Casting
This is the most straightforward approach. We can cast the value from one type to another using parentheses.
2.1.1 Converting Double to Float in Java
Here’s an example of how to convert a double to a float using Casting:
public class ConvertBetweenDoubleAndFloat {
public static void main(String[] args) {
double someDouble = 3.141592653589793;
float someFloat = (float) someDouble;
System.out.println(someDouble); // Prints: 3.141592653589793
System.out.println(someFloat); // Prints: 3.1415927 (loss of precision)
}
}
In this example, casting the double to a float might result in a loss of precision due to the float’s limited decimal representation.
2.1.2 Converting Float to Double in Java
float someFloat = 3.14159f;
double someDouble = (double) someFloat;
System.out.println(someFloat); // Prints: 3.14159
System.out.println(someDouble); // No loss of precision
Since a double can hold more decimal places than a float, converting from float to double won’t cause precision loss.
2.2 Using Class Methods
The Double class provides a method called doubleValue() that returns the double value of a Float object. Similarly, the Float class has a floatValue() method that returns the float value of a Double object.
Example:
Double someDoubleObject = 123.4567890123456;
float someFloat = someDoubleObject.floatValue();
System.out.println(someDoubleObject); // Prints: 123.4567890123456
System.out.println(someFloat); // Prints: 123.45679 (loss of precision)
Float someFloatObject = 3.14159f;
double someDouble = someFloatObject.doubleValue();
System.out.println(someFloatObject); // Prints: 3.14159
System.out.println(someDouble); // Prints: 3.141592653589793 (no loss of precision)
3. Important Considerations
- Precision Loss: When converting from double to float, be aware of potential precision loss. If your application relies on high decimal accuracy, using double might be preferable.
- Memory Efficiency: If memory usage is a concern, and you don’t need the extra precision of doubles, using floats can be beneficial.
4. Conclusion
This article explored converting between double and float data types in Java. By understanding doubles, floats, and the conversion methods, we can make informed decisions about representing floating-point data in our Java programs.
5. Download the Source Code
This was an article on Converting Between Double and Float in Java.
You can download the full source code of this example here: Convert between double and float in Java
