Java Convert double to String

In Java, you can convert a double value to a String using the Double.toString() method or the String.valueOf() method. Here’s an example:

double number = 3.14159;
String strNumber = Double.toString(number); // using Double.toString() method
String strNumber2 = String.valueOf(number); // using String.valueOf() method

System.out.println(strNumber); // Output: "3.14159"
System.out.println(strNumber2); // Output: "3.14159"

Both methods will return a String representation of the double value. The Double.toString() method returns a String object representing the specified double value. The String.valueOf() method also returns a String object representing the specified double value, but it can also handle null arguments.

1) String.valueOf():

String.valueOf() is a method in Java that returns a string representation of the passed argument. This method can take arguments of any data type and convert them to their equivalent string representation.

Here’s an example of using the String.valueOf() method to convert an integer to a string:

int num = 42;
String str = String.valueOf(num);
System.out.println(str); // Output: "42"

In this example, the int variable num is converted to a String using the String.valueOf() method and assigned to the String variable str.

This method is often used in situations where you need to concatenate a non-string object with a string object. For example:

int num = 42;
String str = "The answer is " + String.valueOf(num);
System.out.println(str); // Output: "The answer is 42"

Here, the int variable num is concatenated with the string "The answer is " using the + operator. However, since num is not a String, it needs to be converted to a String using the String.valueOf() method before concatenation can occur.

Java double to String Example: String.valueOf()

Here’s an example of using the String.valueOf() method to convert a double to a String:

double num = 3.14159;
String str = String.valueOf(num);
System.out.println(str); // Output: "3.14159"

In this example, the double variable num is converted to a String using the String.valueOf() method and assigned to the String variable str.

This method works for all types of numerical data types in Java including float, double, int, long, etc. and it can also handle null values as an argument.

double num = 3.14159;
String str = String.valueOf(num);
System.out.println(str); // Output: "3.14159"
    
double num2 = 0.0/0.0;
String str2 = String.valueOf(num2);
System.out.println(str2); // Output: "NaN"

In the above example, String.valueOf() is used to convert num which is a finite number, and num2 which is a NaN value. As you can see, String.valueOf() returns the correct string representation for both values.

2) Double.toString():

Double.toString() is a method in Java that returns a String representation of a double value. This method takes a double value as an argument and returns a String object representing the specified double value.

Here’s an example of using the Double.toString() method to convert a double to a String:

double num = 3.14159;
String str = Double.toString(num);
System.out.println(str); // Output: "3.14159"

In this example, the double variable num is converted to a String using the Double.toString() method and assigned to the String variable str.

This method is similar to using String.valueOf() to convert a double to a String. The main difference is that Double.toString() only works with double values, while String.valueOf() can convert values of any primitive data type to a String.

double num = 3.14159;
String str = Double.toString(num);
System.out.println(str); // Output: "3.14159"
    
float num2 = 2.71828f;
String str2 = Double.toString(num2); // will not compile, cannot pass float to Double.toString()

In the above example, Double.toString() is used to convert num which is a double, and str2 is an attempt to use Double.toString() to convert a float value, which will not compile because Double.toString() only works with double values.

Java double to String Example: Double.toString()

Here’s an example of using the Double.toString() method to convert a double to a String:

double num = 3.14159;
String str = Double.toString(num);
System.out.println(str); // Output: "3.14159"

In this example, the double variable num is converted to a String using the Double.toString() method and assigned to the String variable str.

This method works only for double values, and it’s less flexible than the String.valueOf() method because it only works with double data type.

double num = 3.14159;
String str = Double.toString(num);
System.out.println(str); // Output: "3.14159"
    
double num2 = 0.0/0.0;
String str2 = Double.toString(num2);
System.out.println(str2); // Output: "NaN"

In the above example, Double.toString() is used to convert num which is a finite number, and num2 which is a NaN value. As you can see, Double.toString() returns the correct string representation for both values.

In general, it’s recommended to use String.valueOf() instead of Double.toString() because String.valueOf() is more flexible and can handle values of any primitive data type.