public interface Formattable
Formatter.  This interface allows basic
 control for formatting arbitrary objects.
 For example, the following class prints out different representations of a
 stock's name depending on the flags and length constraints:
  
   import java.nio.CharBuffer;
   import java.util.Formatter;
   import java.util.Formattable;
   import java.util.Locale;
   import static java.util.FormattableFlags.*;
   ...
   public class StockName implements Formattable {
       private String symbol, companyName, frenchCompanyName;
       public StockName(String symbol, String companyName,
                        String frenchCompanyName) {
           ...
       }
       ...
       public void formatTo(Formatter fmt, int f, int width, int precision) {
           StringBuilder sb = new StringBuilder();
           // decide form of name
           String name = companyName;
           if (fmt.locale().equals(Locale.FRANCE))
               name = frenchCompanyName;
           boolean alternate = (f & ALTERNATE) == ALTERNATE;
           boolean usesymbol = alternate || (precision != -1 && precision < 10);
           String out = (usesymbol ? symbol : name);
           // apply precision
           if (precision == -1 || out.length() < precision) {
               // write it all
               sb.append(out);
           } else {
               sb.append(out.substring(0, precision - 1)).append('*');
           }
           // apply width and justification
           int len = sb.length();
           if (len < width)
               for (int i = 0; i < width - len; i++)
                   if ((f & LEFT_JUSTIFY) == LEFT_JUSTIFY)
                       sb.append(' ');
                   else
                       sb.insert(0, ' ');
           fmt.format(sb.toString());
       }
       public String toString() {
           return String.format("%s - %s", symbol, companyName);
       }
   }
 
  When used in conjunction with the Formatter, the above
 class produces the following output for various format strings.
 
 
   Formatter fmt = new Formatter();
   StockName sn = new StockName("HUGE", "Huge Fruit, Inc.",
                                "Fruit Titanesque, Inc.");
   fmt.format("%s", sn);                   //   -> "Huge Fruit, Inc."
   fmt.format("%s", sn.toString());        //   -> "HUGE - Huge Fruit, Inc."
   fmt.format("%#s", sn);                  //   -> "HUGE"
   fmt.format("%-10.8s", sn);              //   -> "HUGE      "
   fmt.format("%.12s", sn);                //   -> "Huge Fruit,*"
   fmt.format(Locale.FRANCE, "%25s", sn);  //   -> "   Fruit Titanesque, Inc."
 
 Formattables are not necessarily safe for multithreaded access. Thread safety is optional and may be enforced by classes that extend and implement this interface.
 Unless otherwise specified, passing a null argument to
 any method in this interface will cause a NullPointerException to be thrown.
| Modifier and Type | Method and Description | 
|---|---|
| void | formatTo(Formatter formatter,
        int flags,
        int width,
        int precision)Formats the object using the provided  formatter. | 
void formatTo(Formatter formatter, int flags, int width, int precision)
formatter.formatter - The formatter.  Implementing classes may call
         formatter.out() or formatter.locale() to obtain the Appendable or Locale used by this
         formatter respectively.flags - The flags modify the output format.  The value is interpreted as
         a bitmask.  Any combination of the following flags may be set:
         FormattableFlags.LEFT_JUSTIFY, FormattableFlags.UPPERCASE, and FormattableFlags.ALTERNATE.  If no flags are set, the default
         formatting of the implementing class will apply.width - The minimum number of characters to be written to the output.
         If the length of the converted value is less than the
         width then the output will be padded by
         '  ' until the total number of characters
         equals width.  The padding is at the beginning by default.  If
         the FormattableFlags.LEFT_JUSTIFY flag is set then the
         padding will be at the end.  If width is -1
         then there is no minimum.precision - The maximum number of characters to be written to the output.
         The precision is applied before the width, thus the output will
         be truncated to precision characters even if the
         width is greater than the precision.  If
         precision is -1 then there is no explicit
         limit on the number of characters.IllegalFormatException - If any of the parameters are invalid.  For specification of all
          possible formatting errors, see the Details section of the
          formatter class specification. Submit a bug or feature 
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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