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How to Convert Int to String in Java? Integer to String Program

When working with Java programming, there often arises a need to convert data from one type to another. One common conversion task is to convert int (integer) to a String in Java. Whether you're working on a Java application or simply trying to manipulate data, understanding how to perform this conversion is an essential skill.

This tutorial is designed to walk you through the process of how to convert int to String in Java, step by step. We will explore multiple methods and techniques, providing you with a comprehensive understanding of how to achieve this task efficiently and effectively.

Why might you need to convert an int to a String in Java, you ask? There are numerous practical scenarios:

  • Displaying Numeric Values: You may want to display an int as part of a message, in a user interface, or on a web page where it's more appropriate to present it as text.

  • Concatenation: String concatenation is a common operation in Java, and sometimes you need to include an int as part of a larger string.

  • File I/O: When reading or writing data to files, you often need to convert between data types, and converting an int to a String is a common transformation.

  • Parsing Data: When working with user input or external data sources, you may receive numeric values as strings and need to convert them back to integers for calculations.

Throughout this tutorial, we'll explore different approaches to handle these situations, from the basic and straightforward to more advanced techniques. By the end, you'll be well-equipped to handle int to String conversion in Java confidently. So, let's dive in and start learning!

Convert Int to String in Java Using String.valueOf()

Here's a program on how to convert int to String in Java using the String.valueOf(intValue) method, along with an explanation of the code and its output:

Code

public class IntToStringExample {
    public static void main(String[] args) {
        // Define an integer variable
        int intValue = 42;

        // Convert the integer to a string using String.valueOf()
        String stringValue = String.valueOf(intValue);

        // Display the original integer and the converted string
        System.out.println("Original Integer: " + intValue);
        System.out.println("Converted String: " + stringValue);
    }
}

Output

Original Integer: 42
Converted String: 42

Explanation

  • We start by defining an integer variable intValue and assign it the value 42.

  • Next, we use the String.valueOf(intValue) method to convert the integer intValue to a string. This method takes an integer as its argument and returns a string representation of that integer.

  • We store the converted string in a variable named stringValue.

  • Finally, we print out both the original integer value and the converted string using System.out.println().

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Convert Integer to String in Java Using Integer.toString()

Below is a Java program to convert int to String using the Integer.toString(intValue) method:

Code

public class IntToStringExample {
    public static void main(String[] args) {
        // Define an integer variable
        int intValue = 42;

        // Convert the integer to a string using Integer.toString()
        String stringValue = Integer.toString(intValue);

        // Display the original integer and the converted string
        System.out.println("Original Integer: " + intValue);
        System.out.println("Converted String: " + stringValue);
    }
}

Output

Original Integer: 42
Converted String: 42

Explanation

  • We start by defining an integer variable intValue and assign it the value 42.

  • Next, we use the Integer.toString(intValue) method to convert the integer intValue to a string. This method is a static method of the Integer class and takes an integer as its argument, returning a string representation of that integer.

  • We store the converted string in a variable named stringValue.

  • Finally, we print out both the original integer value and the converted string using System.out.println().

Int to String in Java Using Concatenation With Empty String

Here's a program to convert int to String in Java language using the third method, which is concatenation with an empty string ("" + intValue):

Code

public class IntToStringExample {
    public static void main(String[] args) {
        // Define an integer variable
        int intValue = 42;

        // Convert the integer to a string by concatenating with an empty string
        String stringValue = "" + intValue;

        // Display the original integer and the converted string
        System.out.println("Original Integer: " + intValue);
        System.out.println("Converted String: " + stringValue);
    }
}

Output

Original Integer: 42
Converted String: 42

Explanation

  • We begin by defining an integer variable intValue and assigning it the value 42.

  • To convert the integer intValue to a string, we use a simple concatenation operation. We concatenate an empty string "" with the integer variable intValue. This causes Java to automatically convert the integer to a string and create a new string containing the result.

  • We store the converted string in a variable named stringValue.

  • Finally, we print out both the original integer value and the converted string using System.out.println().

How to Convert Integer to String in Java Using String.format()

Following is a program on how to convert Java int to String using the String.format("%d", intValue) method, along with an explanation of the code and its output:

Code

public class IntToStringExample {
    public static void main(String[] args) {
        // Define an integer variable
        int intValue = 42;

        // Convert the integer to a string using String.format()
        String stringValue = String.format("%d", intValue);

        // Display the original integer and the converted string
        System.out.println("Original Integer: " + intValue);
        System.out.println("Converted String: " + stringValue);
    }
}

Output

Original Integer: 42
Converted String: 42

Explanation

  • We start by defining an integer variable intValue and assign it the value 42.

  • To convert the integer intValue to a string, we use the String.format("%d", intValue) method. This method takes a format string as its first argument, where "%d" specifies that we want to format an integer, and intValue as the second argument. It returns a formatted string representing the integer.

  • We store the converted string in a variable named stringValue.

  • Finally, we print out both the original integer value and the converted string using System.out.println().