How to convert an int to a string in java?

This post will look at various ways of converting an int to a String in Java.

Below are some of the many ways of converting an int to a String –

Integer.toString() method
String.ValueOf() method
Using + operator
Using StringBuffer or StringBuilder append() function
String.format() method

Let’s look at all of the ways one by one.

Using toString() method

Java has an Integer wrapper class so that we can perform class operations on the int primitive type, and that Integer class has a static toString() method which will take an int as an argument and return a String object. Below is the signature of the method –

public static String toString(int i)

We can use the below line to convert an int to a string.

String str = Integer.toString(i);  // where i is an integer

The whole program of converting an int to a String is shown below.

public class Codekru {

	public static void main(String[] args) {
		int i = 205;
		String str = Integer.toString(i);

		System.out.println(str instanceof String); // will print true
		System.out.println(str); // will print "205"
	}
}

Output –

true
205

Using String.ValueOf() method

String class has a static valueOf() method, which will take an int as an argument and return a String object.

public static String valueOf(int i)

We will let you on a little secret, String .valueOf() method internally uses Integer.toString() method.

Below is the internal implementation of the String.valueOf() function, which takes an int as an argument and converts it into a String.

    public static String valueOf(int i) {
        return Integer.toString(i);
    }

And Below is the example of converting an int to a String using the valueOf() method.

public class Codekru {

	public static void main(String[] args) {
		int i = 205;
		String str = String.valueOf(i);

		System.out.println(str instanceof String); // will print true
		System.out.println(str); // will print "205"
	}
}

Output –

true
205

Using + operator

Do you know we can directly convert an int to a String using the + operator?

public class Codekru {

	public static void main(String[] args) {
		int i = 205;
		int j = 206;
		String str = "";
		str = str + i + j; // acting as a string concatenation operator here
		System.out.println(str instanceof String);  // will print true
		System.out.println(str); // will print "205206"
	}
}

Output

true
205206

Using StringBuffer or StringBuilder append() function

We can also use the append() function in StringBuilder and StringBuffer classes to convert an int to a String. The below code helps us achieve the same.

public class Codekru {

	public static void main(String[] args) {
		int i = 205;
		String str = new StringBuffer().append(i).toString();
		System.out.println(str instanceof String); // will print true
		System.out.println(str); // will print "205"
	}
}

Output –

true
205

String.format() method

We can also use the String class’s static format() method.

public class Codekru {

	public static void main(String[] args) {
		int i = 1234;

		String str = String.format("%d", i);
		System.out.println(str);

	}
}