Java String to long Conversion with examples

In this tutorial, we will see how to convert String to long in Java. There are three ways to convert a String to a long value.

1. Java – Convert String to long using Long.parseLong(String)

Long.parseLong(String): All the characters in the String must be digits except the first character, which can be a digit or a minus ‘-‘. For example – long var = Long.parseInt("-123"); is allowed and the value of var after conversion would be -123.

Java Program to Convert String to long using Long.parseLong(String)

In this example, the string str2 has minus sign ‘-‘ in the beginning, which is why the the value of variable num2 is negative.

public class JavaExample {
    public static void main(String[] args)
    {
	String str = "21111";
	String str2 = "-11111";
		
	//Conversion using parseLong(String) method
	long num = Long.parseLong(str);
	long num2 = Long.parseLong(str2);
	System.out.println(num+num2);		
    }
}

Output:
Java String to Long conversion

2. Java – Convert String to long using Long.valueOf(String)

Long.valueOf(String): Converts the String to a long value. Similar to parseLong(String) method, this method also allows minus ‘-‘ as a first character in the String.

Java Program to Convert String to long using Long.valueOf(String)

public class Example {
   public static void main(String[] args)
   {
       String str = "11111";
       String str2 = "88888";
       //Conversion using valueOf(String) method
       long num = Long.valueOf(str);
       long num2 = Long.valueOf(str2);
       System.out.println(num+num2);		
   }
}

Output:

3. Java – Convert String to long using the constructor of Long class

Long(String s) constructor : Long class has a constructor which allows String argument and creates a new Long object representing the specified string in the equivalent long value. The string is converted to a long value in exactly the manner used by the parseLong(String) method for radix 10.

Java Program for String to long conversion using new Long(String)

public class Example {
   public static void main(String[] args)
   {
       String str = "10000";
       String str2 = "22222";
       //Conversion using Long(String s) constructor
       long num = new Long(str);
       long num2 = new Long(str2);
       System.out.println(num*num2);		
   }
}