Convert float to String and String to float in Java

java

decimal-format

float-conversion

exception-handling

byAlex Kataev·Dec 3, 2024

To convert a float to String in Java, you can use either String.valueOf(floatValue) method or your old high school friend, the + "" trick. For converting a String to float, Float.parseFloat(stringValue) will be your best buddy on Stackoverflow.

// Float to String conversion for when simplicity calls on weekends!!
float myFavoriteFloat = 42.0f;
String fromFloatTheFirstWay = String.valueOf(myFavoriteFloat); // "42.0"
String fromFloatTheAlternateWay = myFavoriteFloat + ""; // "42.0"

// String to Float conversion, because why should numbers have all the fun!
String myStringThatLooksLikeFloat = "42.0";
float toFloat = Float.parseFloat(myStringThatLooksLikeFloat); // 42.0f

Don't forget to put on your safety gear - always handle NumberFormatException when converting String to float to avoid those runtime crash party-poopers.

Precise float to String conversion

Numbers can be a bit fussy about their looks (who isn't?), especially floats. When you need to keep up with float's precision demands, use DecimalFormat to determine its string representation.

import java.text.DecimalFormat;

// Precision matters, said the float at the salon!
float superPreciseFloat = 2.456789f;
DecimalFormat myFloatFormatter = new DecimalFormat("#.##");
String myFloatBecomesStylishString = myFloatFormatter.format(superPreciseFloat); // "2.46"

When strolling back to float-land from stringtown, ensure your string has had a nice trim and format check to keep up with the float precision.

String to Float conversion with special treatment

Converting from string to float may lead to an impatient NumberFormatException on encountering ill-formatted inputs. So, keep your chill with some solid exception handling to make your code a zen-master.

// When life gives you weird strings, catch exceptions!
try {
    String mySuperSpecialString = "10.5";
    float stringTurnsIntoFloat = Float.parseFloat(mySuperSpecialString);
} catch (NumberFormatException e) {
    System.out.println("My string refuses to be a float. How rude!");
}

To sidestep any precision loss during conversion and to meet the high-precision demands, set the stage with DecimalFormat or transform using Float.valueOf(string) for the next float supermodel.

Fun with formats and comparisons!

Float.valueOf(string) can be a handy dandy alternative to Float.parseFloat(string).
Floats love direct comparison. Comparing them as strings can give you some surprise parties you didn't sign up for, thanks to different precisions.
Let your strings enjoy a bit of wardrobe change with DecimalFormat before comparing them to ensure they match float's precision and tastes.

Dealing with noisy data and multiple representations

Some strings come with extra luggage like whitespaces or invalid formats. Trim and validate input strings before departure to smooth your journey to float.

// Noisy string... just another Monday!
String noisyInput = "  7.89 ";
float readyForTakeOff = Float.parseFloat(noisyInput.trim());

Different string tickets like "25.0" and "25.00" land you at the same float destination. Keep this mind trick in your "How-to java" hat when dealing with comparisons.

Always test your code for reliability

Make sure your conversion code can handle diverse inputs. Include edge cases like maximum float values, scientific notation, and special float literals like NaN and Infinity.

// What?! Strings can be scientific too!
String scientificString = "1.23e4";
float scienceLovingFloat = Float.parseFloat(scienticficString); // 12300.0f

Consistent results under all conditions = winning stackoverflow gold stars!

explain-codes / Java / Convert float to String and String to float in Java

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