Java Integer valueOf() Method

The Integer.valueOf() method in Java is used to convert a String or an int value into an Integer object. This method has several overloaded versions, each providing different functionalities for creating Integer objects. 

Table of Contents

1. Introduction
2. valueOf() Method Syntax
3. Overloaded Versions
   • valueOf(int i)
   • valueOf(String s)
   • valueOf(String s, int radix)
4. Examples
   • Converting an int to an Integer
   • Converting a String to an Integer
   • Converting a String with a Radix to an Integer
5. Real-World Use Case
6. Conclusion

Introduction

The Integer.valueOf() method is a static method in the Integer class in Java. It converts primitive int values and String representations of numbers into Integer objects. This method is useful when you need to work with Integer objects instead of primitive int values.

valueOf()() Method Syntax

There are three primary overloaded versions of the valueOf() method in the Integer class:

1. public static Integer valueOf(int i)
2. public static Integer valueOf(String s) throws NumberFormatException
3. public static Integer valueOf(String s, int radix) throws NumberFormatException

Overloaded Versions

1. valueOf(int i)

This method converts the primitive int value i to an Integer object.

public static Integer valueOf(int i)

• i: The integer to be converted to an Integer object.

The method returns:

• An Integer object representing the specified integer value.

2. valueOf(String s)

This method converts the string s to an Integer object.

public static Integer valueOf(String s) throws NumberFormatException

• s: The string to be converted to an Integer object.

The method returns:

• An Integer object representing the value of the specified string.

Throws:

• NumberFormatException if the string does not contain a parsable integer.

3. valueOf(String s, int radix)

This method converts the string s to an Integer object using the specified radix.

public static Integer valueOf(String s, int radix) throws NumberFormatException

• s: The string to be converted to an Integer object.
• radix: The radix to be used in interpreting the string.

The method returns:

• An Integer object representing the value of the specified string in the specified radix.

Throws:

• NumberFormatException if the string does not contain a parsable integer.

Examples

Converting an int to an Integer

The valueOf(int i) method converts a primitive int to an Integer object.

Example

public class ValueOfIntExample {
    public static void main(String[] args) {
        int number = 123;
        Integer integerObject = Integer.valueOf(number);

        System.out.println("Integer object: " + integerObject);
    }
}

Output:

Integer object: 123

In this example, the primitive integer 123 is converted to an Integer object.

Converting a String to an Integer

The valueOf(String s) method converts a string to an Integer object.

Example

public class ValueOfStringExample {
    public static void main(String[] args) {
        String numberString = "456";
        Integer integerObject = Integer.valueOf(numberString);

        System.out.println("Integer object: " + integerObject);
    }
}

Output:

Integer object: 456

In this example, the string "456" is converted to an Integer object.

Converting a String with a Radix to an Integer

The valueOf(String s, int radix) method converts a string in a specified radix to an Integer object.

Example

public class ValueOfStringWithRadixExample {
    public static void main(String[] args) {
        String binaryString = "1111";
        Integer integerObject = Integer.valueOf(binaryString, 2);

        System.out.println("Integer object (binary): " + integerObject);

        String hexString = "1A";
        integerObject = Integer.valueOf(hexString, 16);

        System.out.println("Integer object (hexadecimal): " + integerObject);
    }
}

Output:

Integer object (binary): 15
Integer object (hexadecimal): 26

In this example, the binary string "1111" is converted to the integer 15, and the hexadecimal string "1A" is converted to the integer 26.

Real-World Use Case

Parsing Configuration Values

In a real-world application, you might use the Integer.valueOf() method to parse configuration values from a properties file or environment variables.

Example

import java.util.Properties;

public class ConfigurationExample {
    public static void main(String[] args) {
        Properties properties = new Properties();
        properties.setProperty("maxConnections", "100");
        properties.setProperty("timeout", "30");

        Integer maxConnections = Integer.valueOf(properties.getProperty("maxConnections"));
        Integer timeout = Integer.valueOf(properties.getProperty("timeout"));

        System.out.println("Max Connections: " + maxConnections);
        System.out.println("Timeout: " + timeout);
    }
}

Output:

Max Connections: 100
Timeout: 30

In this example, the configuration values are parsed from a properties file and converted to Integer objects using the Integer.valueOf() method.

Conclusion

The Integer.valueOf() method in Java is a versatile tool for converting int values and String representations of numbers into Integer objects. By understanding how to use the different overloaded versions of this method, you can efficiently handle tasks that involve creating and working with Integer objects in your Java applications. Whether you are dealing with base 10, different numeral systems, or parsing configuration values, the valueOf() method provides a reliable solution for these tasks.