Example 1: Java Program to Convert string to double using parseDouble()
class Main { public static void main(String[] args) { // create string variables String str1 = "23"; String str2 = "456.6"; // convert string to double // using parseDouble() double num1 = Double.parseDouble(str1); double num2 = Double.parseDouble(str2); // print double values System.out.println(num1); // 23.0 System.out.println(num2); // 456.6 } } In the above example, we have used the parseDouble() method of the Double class to convert the string variables into double.
Here, Double is a wrapper class in Java. To learn more, visit the Java Wrapper Class.
Note: The string variables should represent the number value. Otherwise, the compiler will throw an exception. For example,
class Main { public static void main(String[] args) { // create a string variable String str1 = "Programiz"; // convert string to double // using parseDouble() double num1 = Double.parseDouble(str1); // print double values System.out.println(num1); // throws NumberFormatException } } Example 2: Java Program to Convert string to double using valueOf()
We can also convert the string variables into a double using the valueOf() method. For example,
class Main { public static void main(String[] args) { // create string variables String str1 = "6143"; String str2 = "21312"; // convert String to double // using valueOf() double num1 = Double.valueOf(str1); double num2 = Double.valueOf(str2); // print double values System.out.println(num1); // 6143.0 System.out.println(num2); // 21312.0 } } In the above example, the valueOf() method of Double class converts the string values into the double.
Here, the valueOf() method actually returns an object of the Double class. However, the object is automatically converted into the primitive type. This is called unboxing in Java. To learn more, visit Java autoboxing and unboxing.
That is,
// valueOf() returns object of Double // object is converted into double double num1 = Double obj = Double.valueOf(str1); Example 3: Java Program to Convert a String containing comma to double
class Main { public static void main(String[] args) { // create string variables String str = "614,33"; // replace the , with . str = str.replace(",", "."); // convert String to double // using valueOf() double value = Double.parseDouble(str); // print double value System.out.println(value); // 614.33 } } In the above example, we have created a string named str. Notice the line,
str = str.replace(",", "."); Here, the replace() method replaces the comma present in the string with the dot character. To learn more about replacing the character, visit Java String replace().
We then used the parseDouble() method to convert the string into double.