println( "String to double conversion using valueOf : " + value) now let's use Double.valueOf() method to get double from String String str = "8.23" println( "String " + number + " is parse to double value : " + d) let's first start converting String to double // there are three ways to convert a String to double in Java // parseDouble(), valueOf() and Double() constructor // Using parseDouble() to parse String to double in Java String number = "6.24" * Java Program to convert String to double in Java and vice-versa. We will use the knowledge we gain in the first two paragraphs. In the following example, we will first learn how to convert a String to double and then opposite. Just like other valueOf() methods this can also cache frequently used values along with leveraging String pool.Įnough of theory, now let's see some code in working. Since String provides a set of overloaded methods to convert every single data type like boolean, short, char, int, long, float, and double it makes sense to leverage that. The third method uses the valueOf() method of the String class to convert a double value to a String. The second method is mainly for the Double objects, but don't worry even if you have a double value you can leverage autoboxing to first convert it into a Double object and then just call the toString() method on it to get an equivalent String in Java. "" should be the first argument or else + operator will do addition instead of String concatenation. Just make sure that empty String literal i.e. The first one is very simple, just use the + operator with an empty String and a double variable and you will get an equivalent String literal containing a double value. On the reverse side also there are three main ways to convert a double variable to String in Java In cases where Double object is got autoboxing in Java will take care of converting to double primitive value. You don't need to worry about which method returns a double primitive value and which method returns Double object because autoboxing will take care of double to Double object conversion automatically.īTW, just for your information both parseDouble() and valueOf() returns a double primitive value but new Double() is a constructor it returns a Double object. If you are not looking to convert String to double but to format double values to String, then please check my earlier post, formatting floating-point numbers in Java.Īs I said, the following are three main ways to convert a String containing floating-point value into double primitive and Double object. On the other hand, if you use a new Double(String value) constructor then you will always get a new Double object, creating memory pressure for your application.īTW, in this article, we will not only learn how to convert String to double value but also how to convert Double to String, as it's important to know both sides of a conversion. Some of you might be curious and thinking if one method can do the job then why we have three methods for String to Double or double conversion? Well, their purpose is a little bit different and they also provide some other service.įor example, you should be using Double.valueOf() method if you frequently need to convert String to Double because it will likely give better performance by caching frequently used values just like Integer.valueOf() method does. This method will throw NullPointerException if the string you are passing is null and NumberFormatExceptionif String is not containing a valid double value e.g. Rest of the methods like valueOf() and constructor uses parseDouble() internally. Out of all these methods, the core method is parseDouble() which is specially designed to parse a String containing floating-point value into the Double object. Here's an example program that demonstrates this approach: import are three ways to convert a String to double value in Java, Double.parseDouble() method, Double.valueOf() method and by using new Double() constructor and then storing the resulting object into a primitive double field, autoboxing in Java will convert a Double object to the double primitive in no time. The first method involves using the StringTokenizer class, which allows you to break a string into tokens based on a delimiter. Method 1: Using the StringTokenizer Class We will provide step-by-step explanations along with code examples to help you understand the process thoroughly. In this tutorial, we will explore different methods to convert a string to a double array in Java. This could be useful when dealing with data parsing, mathematical calculations, or any other scenario where numeric data is involved. In Java, there are various scenarios where you might need to convert a string representation of numbers into a double array.
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