Convert Double to String

Introduction

In Java, a double is a data type that can store floating-point values, while a string is a sequence of characters. Converting between the two types is a common operation in programming. This lab will guide you through the steps to convert a double to a string in Java.

Declare a Double variable

Declare a Double variable doubleValue and initialize it with the value 10.55.

Double doubleValue = 10.55;

Use .toString() method

Use the .toString() method from the Double class to convert the double to a string. Save the string result to a new String variable named stringValue.

String stringValue = doubleValue.toString();

Use String.format() method

Use the String.format() method to create a formatted string representation of the doubleValue with a precision of two decimal places. Save the result to a String variable named formattedString.

String formattedString = String.format("%.2f", doubleValue);

Use String.valueOf() method

Use the String.valueOf() method to convert the doubleValue to a string. Save the result to a String variable named valueOfString.

String valueOfString = String.valueOf(doubleValue);

Use + operator

Use the + operator to concatenate a string with the doubleValue. Save the result to a String variable named concatenatedString.

String concatenatedString = "" + doubleValue;

Print the results

Print all the string variables created in Steps 3 to 6 using System.out.println();

System.out.println("doubleValue as String: " + stringValue);
System.out.println("Formatted String: " + formattedString);
System.out.println("StringValueOf: " + valueOfString);
System.out.println("Concatenated String: " + concatenatedString);

Compile and run

Compile the Java file using javac DoubleToString.java and run it using java DoubleToString.

javac DoubleToString.java && java DoubleToString

Output

The output should be:

doubleValue as String: 10.55
Formatted String: 10.55
StringValueOf: 10.55
Concatenated String: 10.55

Summary

In this lab, we learned how to convert a double to a String in Java. We used four different approaches to achieve this - using the .toString() method, String.format() method, String.valueOf() method, and the + operator.