Java String to long Conversion With Examples

In this tutorial, you will learn how to convert String to long in Java. There are following three ways to convert a String to a long value.

• Long.parseLong() Method
• Long.valueOf() Method
• Long(String s) Constructor of Long class

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

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

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:

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

public class JavaExample {
  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);
    System.out.println(num2);
  }
}

Output:

11111
88888

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

Long(String s) constructor: Long class has a constructor that 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

public class JavaExample {
  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);
    System.out.println(num2);
  }
}

Output:

10000
22222

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• Java String to boolean Conversion

Reference: Long class JavaDoc