String with commas to double java

Java Convert String to Double examples

In this guide we will see how to convert String to Double in Java. There are three ways to convert String to double.

1. Java – Convert String to Double using Double.parseDouble(String) method
2. Convert String to Double in Java using Double.valueOf(String)
3. Java Convert String to double using the constructor of Double class – The constructor Double(String) is deprecated since Java version 9

1. Java Convert String to Double using Double.parseDouble(String)

public static double parseDouble(String str) throws NumberFormatException

This method returns the double representation of the passed String argument. This method throws NullPointerException , if the specified String str is null and NumberFormatException – if the string format is not valid. For example, if the string is “122.20ab” this method would throw NumberFormatException.

String str="122.202"; double dnum = Double.parseDouble(str);

The value of variable dnum of double type would be 122.202 after conversion.

Lets see the complete example of the conversion using parseDouble(String) method.

Example 1: Java Program to convert String to double using parseDouble(String)

Output:

2. Java Convert String to Double using Double.valueOf(String)

The valueOf() method of Double wrapper class in Java, works similar to the parseDouble() method that we have seen in the above java example.

String str = "122.111"; double dnum = Double.valueOf(str);

The value of dnum would be 122.111 after conversion

Lets see the complete example of conversion using Double.valueOf(String) method.

Example 2: Java Program to convert String to double using valueOf(String)

Output:

3. Java Convert String to double using the constructor of Double class

Note: The constructor Double(String) is deprecated since Java version 9

String str3 = "999.333"; double var3 = new Double(str3);

Double class has a constructor which parses the String argument that we pass in the constructor, and returns an equivalent double value.

public Double(String s) throws NumberFormatException

Using this constructor we can create a new object of the Double class by passing the String that we want to convert.

Example 3: Java Program to convert String to double using the constructor of Double class

In this example we are creating an object of Double class to convert the String value to double value.

References:

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How to convert Java String to double

In Java, a String can be converted into a double value by using the Double.parseDouble() method. Also, a String can be converted into a Double object using the Double.valueOf() method.

Whenever a data(numerical) is received from a TextField or a TextArea it is in the form of a String and if we want double type then it is required to be converted into a double before performing any mathematical operation. This is done via parseDouble() method.

1. By Using Double.parseDouble() Method

The parseDouble() method is a part of the Double class. It is a static method and is used to convert a String into a double.

Example 1:

Here, a String value is converted into double type value by using the parseDouble() method. See the example below.

public class StudyTonight < public static void main(String args[]) < String s="454.90"; //String Decleration double i = Double.parseDouble(s); // Double.parseDouble() converts the string into double System.out.println(i); >> 

2. Buy Using Double.valueOf() Method

The valueOf() method is a part of Double class. This method is used to convert a String into a Double Object.

Example 2:

Here, a String value is converted into a double value by using the valueOf() method.

public class StudyTonight < public static void main(String args[]) < try < String s1 = "500.77"; //String declaration double i1 = Double.valueOf(s1); // Double.valueOf() method converts a String into Double System.out.println(i1); String s2 = "mohit"; //NumberFormatException double i2 = Double.valueOf(s2); System.out.println(i2); >catch(Exception e) < System.out.println("Invalid input"); >> >

Example 3:

If we want to convert a value that contains commas then use replaceAll() method to replace that commas and the use parseDouble() method to get double value. Here, a String value is converted into double values taking the commas into consideration.

public class StudyTonight < public static void main(String args[]) < String s = "4,54,8908.90"; //String Decleration //replace all commas if present with no comma String s1 = s.replaceAll(",","").trim(); // if there are any empty spaces also take it out. String f = s1.replaceAll(" ", ""); //now convert the string to double double result = Double.parseDouble(f); System.out.println("Double value is : "+ result); >> 

Double value is : 4548908.9

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Разобрать строку в число с плавающей запятой или int в Java

В этом посте мы обсудим, как преобразовать строку в число double, float или int в Java.

1. Использование Double.parseDouble() метод

Стандартное решение для анализа строки для получения соответствующего двойного значения использует метод Double.parseDouble() метод.

The Double.parseDouble() броски метода NumberFormatException если строка не содержит анализируемого двойника. Чтобы избежать внезапного завершения программы, заключите свой код в блок try-catch.

Обратите внимание, вы не можете анализировать такие строки, как 1.1 с использованием Integer.parseInt() метод. Чтобы получить целочисленное значение, вы можете привести результирующее двойное значение.

2. Использование Float.parseFloat() метод

В качестве альтернативы вы можете использовать Float.parseFloat() метод для синтаксического анализа строки в число с плавающей запятой.

Чтобы получить целочисленное значение, приведите результирующее значение с плавающей запятой, как обсуждалось ранее.

3. Использование Integer.parseInt() метод

Чтобы получить целочисленное значение, представленное строкой в десятичном виде, вы можете использовать Integer.parseInt() метод, который анализирует строку как десятичное целое число со знаком.

4. Использование Number class

Чтобы проанализировать текст с начала заданной строки для получения числа, вы можете использовать метод parse() метод NumberFormat учебный класс. Этот метод может не использовать всю строку и выдает ParseException если строка начинается с любого неразборчивого нечислового символа.

The NumberFormat.parse() метод возвращает Number экземпляр класса, который предлагает intValue() , longValue() , floatValue() , doubleValue() , byteValue() , а также shortValue() методы для получения значения указанного числа в качестве соответствующего типа метода.

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Format Number with Commas in Java

In this post, we will see how to format number with commas in java.

How To Add Commas to Number in Java

There are multiple ways to format number with commas in java. Let’s go through them.

1. Using DecimalFormat

DecimalFormat can be used by providing formatting Pattern to format number with commas in java.
Here is an example:

2. Using String’s format() method

You can also use String’s static method format() to format number with commas in java. This method is similar to System.out.printf .
Here is an example:

For format String «%,.2f» means separate digit groups with commas and «.2» means round number to 2 decimal places in java.

Further reading:

Format double to 2 decimal places in Java

Format number with Currency in Java

3. Using System.out.printf

If you want to print number with commas, this is best way to print number with commas on console.
Here is an example:

4. Using Formatter

You can use java.util.Formatter ‘s format() method to format number with commas in java. This is similar to System.out.printf method.
Here is an example:

5. Using NumberFormat

You can also use NumberFormat ‘s setMaximumFractionDigits() to put constraint on number by decimal places and use its format() method to format number with commas in java.
Here is an example:

That’s all about How to format number with commas in java

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