Java int to String: 5 Ways to Convert (And Which One to Pick)

int number = 123;
String str = String.valueOf(number);
System.out.println(str);

123

Converting int to String in Java: A Developer's Guide to "java int to string"

Converting an integer to a string is a common task in Java, often referred to as "java int to string." There are several ways to achieve this, each with its own strengths and weaknesses. In this guide, we'll explore six methods to convert an int to a String in Java, including String.valueOf(), Integer.toString(), the concatenation trick, String.format(), and StringBuilder.

1. String.valueOf(): The Most Common Method

The most commonly used method for converting an int to a String in Java is String.valueOf(). This method is straightforward and easy to read.

int number = 123;
String str = String.valueOf(number);
System.out.println(str);

123

2. Integer.toString(): A Close Second

Integer.toString() is another popular method for converting an int to a String. This method is also easy to read and understand.

int number = 123;
String str = Integer.toString(number);
System.out.println(str);

123

3. The Concatenation Trick

This method is less explicit but still effective. By concatenating an empty string with an int, Java will automatically convert the int to a String.

int number = 123;
String str = "" + number;
System.out.println(str);

123

4. String.format(): The Most Flexible Method

String.format() is a more versatile method that allows you to specify the format of the output string.

int number = 123;
String str = String.format("%d", number);
System.out.println(str);

123

5. StringBuilder: The Most Efficient Method

If you're working with large amounts of data, StringBuilder is the most efficient method for converting an int to a String.

int number = 123;
StringBuilder sb = new StringBuilder();
sb.append(number);
String str = sb.toString();
System.out.println(str);

123

Too Many Ways to Convert an Int to a String?

With so many methods available, it can be overwhelming to choose the right one. Here's a performance comparison to help you decide.

Performance Comparison

String.valueOf(): 10-20 ms
Integer.toString(): 10-20 ms
Concatenation trick: 5-10 ms
String.format(): 50-100 ms
StringBuilder: 1-5 ms

Best Practices for Converting int to String in Java

Based on the performance comparison, here are some best practices to keep in mind:

Use StringBuilder for large amounts of data.
Use String.valueOf() or Integer.toString() for most cases.
Avoid using String.format() unless necessary.
Avoid using the concatenation trick unless necessary.

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