Java String valueOf() method
Syntax and Examples

Introduction

The valueOf() method in Java's String class is a handy tool for converting various data types (like booleans, characters, numbers, and objects) into their string representations. It’s essentially a way to easily create strings from different kinds of values without needing to manually concatenate them.

Syntax

public static String valueOf(boolean b)
public static String valueOf(char c)
public static String valueOf(char[] data)
public static String valueOf(char[] data, int offset, int count)
public static String valueOf(double d)
public static String valueOf(float f)
public static String valueOf(int i)
public static String valueOf(long l)
public static String valueOf(Object obj)

Parameters

Here's a breakdown of the parameters each valueOf() overload accepts:

Parameter	Description
b (boolean)	The boolean value to convert to a string.
c (char)	The character to convert to a string.
data (char[])	An array of characters to convert to a string.
data (char[]), offset (int), count (int)	A portion of the character array, starting at index offset and containing count characters, to convert to a string.
d (double)	The double value to convert to a string.
f (float)	The float value to convert to a string.
i (int)	The integer value to convert to a string.
l (long)	The long value to convert to a string.
obj (Object)	Any object whose toString() method is called to produce the string representation.

Return Value

All overloads of the valueOf() method return a String representing the value passed as input.

Examples

Example 1: Converting a Boolean to a String

This example demonstrates how to convert a boolean value (true or false) into its string equivalent using valueOf().

boolean myBool = true;
String boolAsString = String.valueOf(myBool);
System.out.println(boolAsString); // Output: true

true

The String.valueOf(myBool) call takes the boolean variable myBool and transforms it into a string, which is then stored in the boolAsString variable. When printed to the console, we see the string representation of the boolean value.

Example 2: Converting a Character to a String

Here's how you can use valueOf() to convert a single character into a string.

char myChar = 'A';
String charAsString = String.valueOf(myChar);
System.out.println(charAsString); // Output: A

A

Similar to the boolean example, this converts a character 'A' into its string form.

Example 3: Converting a Character Array to a String

This demonstrates converting an entire character array to a single string.

char[] myCharArray = {'H', 'e', 'l', 'l', 'o'}; 
String charArrayAsString = String.valueOf(myCharArray);
System.out.println(charArrayAsString); // Output: Hello

Hello

The character array myCharArray is transformed into the string “Hello”. This is equivalent to manually concatenating each character.

Example 4: Converting a Portion of a Character Array

This example shows how to extract a specific section of a character array and convert it into a string using the offset and count parameters.

char[] myCharArray = {'H', 'e', 'l', 'l', 'o'}; 
String partialString = String.valueOf(myCharArray, 1, 3);
System.out.println(partialString); // Output: ell

ell

The code extracts a substring from the array starting at index 1 and containing 3 characters ('e', 'l', 'l'), which are then combined into the string “ell”.

Example 5: Converting an Integer to a String

This illustrates converting an integer value to its string representation.

int myInt = 123;
String intAsString = String.valueOf(myInt);
System.out.println(intAsString); // Output: 123

123

The integer variable myInt is converted to the string “123”. This is useful for displaying numerical values in a user interface or concatenating them with other strings.

Example 6: Converting an Object to a String

This shows how to convert any object into its string representation by calling its toString() method through the `valueOf()` function. This is useful for debugging and logging.

class MyObject {
    private int value;

    public MyObject(int value) {
        this.value = value;
    }

    @Override
    public String toString() {
        return "MyObject with value: " + value;
    }
}

MyObject myObj = new MyObject(42);
String objectAsString = String.valueOf(myObj);
System.out.println(objectAsString); // Output: MyObject with value: 42

MyObject with value: 42

The `toString()` method of the MyObject is invoked by using String.valueOf(myObj), and its returned string is assigned to variable objectAsString.