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The Java string format() method returns a formatted string using the specified locale(or default locale), specified format string and arguments.

Syntax

public static String format(String format,
                            Object... args)
public static String format(Locale l,
                            String format,
                            Object... args)                            

Parameters

format Specify a format string.
args Specify the arguments referenced by the format specifiers in the format string. If there are more arguments than format specifiers, the extra arguments are ignored. The number of arguments is variable and may be zero.
l Specify the locale to apply during formatting.

Return Value

Returns a formatted string.

Exception

throws IllegalFormatException, If a format string contains an illegal syntax, a format specifier that is incompatible with the given arguments, insufficient arguments given the format string, or other illegal conditions.

Example:

In the below example, format() method returns a formatted string using default locale, specified format string and arguments.

public class MyClass {
  public static void main(String[] args) {
    String str1 = String.format("1. %s", "Hello");
    String str2 = String.format("2. %f", 10.565);

    //returns 10 fractional character filling with 0
    String str3 = String.format("3. %5.10f", 10.565);

    //printing all formatted strings
    System.out.println(str1);
    System.out.println(str2);
    System.out.println(str3);
  }
}

The output of the above code will be:

1. Hello
2. 10.565000
3. 10.5650000000

Java String format Specifier

The below table describes the format specifier supported by Java String.

SpecifierData TypeOutput
%afloating point except BigDecimalReturns Hex output of floating point number
%bAny type"true" if non-null, "false" if null
%ccharacterUnicode character
%dinteger including byte, short, int, long, bigintDecimal Integer
%efloating pointdecimal number in scientific notation
%ffloating pointdecimal number
%gfloating pointdecimal number, possibly in scientific notation depending on the precision and value
%hAny typeHex String of value from hashCode() method
%nnonePlatform-specific line separator
%ointeger including byte, short, int, long, bigintOctal number
%sAny typeString value
%tDate/Time including long, Calendar, Date and TemporalAccessor%t is the prefix for Date/Time conversions. More formatting flags are needed after this.
%xinteger including byte, short, int, long, bigintHex string

Example:

In the below example, multiple arguments are used to return the formatted string.

public class MyClass {
  public static void main(String[] args) {
    String name = "John";
    int age = 25;

    //formatting string
    String MyString = String.format("My name is %s and"
                         + " I am %d years old.", name, age);

    //printing the formatted string
    System.out.println(MyString);
  }
}

The output of the above code will be:

My name is John and I am 25 years old.

Example:

In the below example, the string is formatted using specified locale.

import java.util.*;

public class MyClass {
  public static void main(String[] args) {
    String name = "Marry";
    int age = 22;
    Locale l = new Locale("English", "US"); 

    //formatting string using specified locale
    String MyString = String.format(l, "My name is %s and"
                         + " I am %d years old.", name, age);

    //printing the formatted string
    System.out.println(MyString);
  }
}

The output of the above code will be:

My name is Marry and I am 22 years old.

❮ Java String Methods