Java Float Numbers

Understand the float type: use float constants, casts to float values and floats as arguments.

Float. This is a floating-point, 4-byte number. A float is like a double but only has 4 bytes (a double has twice as many bytes).

With this type, we can store numbers with a decimal place. A float can be cast to a double without any special syntax. But we must be careful when converting from a double to a float.

Float examples. Here are two syntax forms for creating a float value. We can use (float) to specify the type. And the lowercase "f" specifies a float literal.

Bytes: In Java we find the handy "BYTES" constants. These tell us exactly how many bytes are used by a type.

Java program that uses float public class Program { public static void main(String[] args) { // Use a float variable. // ... Uses a float cast. float number = (float) 10.5; System.out.println(number); // This syntax also works. float number2 = 10.75f; System.out.println(number2); // A float is 4 bytes. System.out.println(Float.BYTES); } } Output 10.5 10.75 4

Max, min values. Floats can store a wide range of values. But with floats we also find a "normal values" concept. A normal value is within a "balanced range" of values.

Java program that uses max, min floats public class Program { public static void main(String[] args) { float max = Float.MAX_VALUE; float minNormal = Float.MIN_NORMAL; float min = Float.MIN_VALUE; // Print some float values. System.out.println(max); System.out.println(minNormal); System.out.println(min); } } Output 3.4028235E38 1.17549435E-38 1.4E-45

Float, double arguments. Suppose we have a method that receives a double argument. We can pass floats or doubles to it—these values are all "widened" to match the method signature.

Java program that passes float, double arguments public class Program { static void print(double value) { System.out.println(value); } public static void main(String[] args) { // We can pass a float or a double as a double argument. print(100f); print(100d); } } Output 100.0 100.0

Float argument error. We cannot pass a double to a method that requires a float. An error will occur. For this reason, requiring doubles as the parameter type in methods is more compatible.

Java program that causes float argument error public class Program { static void print(float value) { System.out.println(value); } public static void main(String[] args) { // This will not compile. print(100d); } } Output The method print(float) in the type Program is not applicable for the arguments (double)

Cannot convert from double. We cannot convert a double to a float without an explicit cast expression. This prevents data loss when you might not expect it.

Narrowing: For a narrowing cast, like from double to float, some data loss is possible (although it might not occur).

Java program that causes double, float type error public class Program { public static void main(String[] args) { // This will not compile. // ... We must cast the double to a float. double valueD = 100.5d; float valueF = valueD; System.out.println(valueF); } } Output Type mismatch: cannot convert from double to float

Float cast. With an explicit cast, we can convert a double to a float. We can also specify casts when not required just to make our code clearer.Cast

Java program that uses float cast public class Program { public static void main(String[] args) { // Cast double to float. double valueD = 200.75d; float valueF = (float) valueD; System.out.println(valueF); } } Output 200.75

Some research. I found that a normal number is a float that is within a balanced range. This is a technical detail. If you understand all the details, I admire your ability level.

Quote: In computing, a normal number is a non-zero number in a floating-point representation which is within the balanced range supported by a given floating-point format: it is a floating point number that can be represented without leading zeros in its significand.

Normal number: Wikipedia

A summary. Floats are a 4-byte floating point format. We must cast doubles to floats with an expression. But for going from float to double, in a widening cast, no expression is needed.

The Dev Codes

.Net

.NET Array Dictionary List String 2D Async DataTable Dates DateTime Enum File For Foreach Format IEnumerable If IndexOf Lambda LINQ Parse Path Process Property Regex Replace Sort Split Static StringBuilder Substring Switch Tuple

Java

Core Array ArrayList HashMap String 2D Cast Character Console Deque Duplicates File For Format HashSet If IndexOf Lambda Math ParseInt Process Random Regex Replace Sort Split StringBuilder Substring Switch Vector While

TheDeveloperBlog.com

Java Float Numbers

Related Links:

.Net

Java

Related Links