Java String format() Method With Examples

In java, String format() method returns a formatted string using the given locale, specified format string, and arguments. We can concatenate the strings using this method and at the same time, we can format the output concatenated string.

Syntax: There is two types of string format() method

public static String format(Locale loc, String form, Object... args)

public static String format(String form, Object... args)

Parameter:

• The locale value to be applied on the format() method
• The format of the output string.
• args specifying the number of arguments for the format string. It may be zero or more.

Return Type: Formatted string. 

Exception Thrown:

• NullPointerException: If the format is null.
• IllegalFormatException: If the format specified is illegal or there are insufficient arguments.

Example 1:

java

// Java program to demonstrate
// working of format() method

// Main class
class GFG {

    // MAin driver method
    public static void main(String args[])
    {
        // Custom input string to be formatted
        String str = "GeeksforGeeks";

        // Concatenation of two strings
        String s = String.format("My Company name is %s", str);

        // Output is given upto 8 decimal places
        String str2 = String.format("My answer is %.8f", 47.65734);

        // Here answer is supposed to be %15.8f" and
        // "47.65734000" there are 15 spaces
        String str3 = String.format("My answer is %15.8f",
                                    47.65734);

        // Print and display strings
        System.out.println(s);
        System.out.println(str2);
        System.out.println(str3);
    }
}

Output

My Company name is GeeksforGeeks
My answer is 47.65734000
My answer is     47.65734000

Example 2:

java

// Java program to demonstrate Concatenation of Arguments
// to the string using format() method

// Main class
class GFG {

    // Main driver method
    public static void main(String args[])
    {
        // Custom input string to be formatted
        String str1 = "GFG";
        String str2 = "GeeksforGeeks";

        // %1$ represents first argument
        // %2$ second argument
        String str = String.format(
            "My Company name"
                + " is: %1$s, %1$s and %2$s",
            str1, str2);

        // Print and display the formatted string
        System.out.println(str);
    }
}

Output:

My Company name is: GFG, GFG and GeeksforGeeks

Example 3:

java

// Java program to Illustrate Left Padding
// using format() method

// Main class
class GFG {

    // Main driver method
    public static void main(String args[])
    {
        // Custom integer number
        int num = 7044;

        // Output is 3 zero's("000") + "7044",
        // in total 7 digits
        String str = String.format("%07d", num);

        // Print and display the formatted string
        System.out.println(str);
    }
}

Output:

0007044