How can I create a Java method that accepts a variable number of arguments

Question

For example  Java s own String format   supports a variable number of arguments   String format  Hello  s  ABC  d     World   123       gt  Hello World  ABC 123    How can I make my own function that accepts a variable number of arguments     Follow-up question   I m really trying to make a convenience shortcut for this   System out println  String format        a  b  c       So that I can call it as something less verbose like this   print        a  b  c     How can I achieve this

User · Answer

This is known as varargs see the link here for more details

In past java releases, a method that took an arbitrary number of values required you to create an array and put the values into the array prior to invoking the method. For example, here is how one used the MessageFormat class to format a message:

Object[] arguments = {
    new Integer(7),
    new Date(),
    "a disturbance in the Force"
};
    String result = MessageFormat.format(
        "At {1,time} on {1,date}, there was {2} on planet "
         + "{0,number,integer}.", arguments);

It is still true that multiple arguments must be passed in an array, but the varargs feature automates and hides the process. Furthermore, it is upward compatible with preexisting APIs. So, for example, the MessageFormat.format method now has this declaration:

public static String format(String pattern,
                            Object... arguments);

User · Answer

The following will create a variable length set of arguments of the type of string   print String arg1  String    arg2    You can then refer to arg2 as an array of Strings  This is a new feature in Java 5

User · Answer

Take a look at the Java guide on varargs    You can create a method as shown below  Simply call System out printf instead of System out println String format       public static void print String format  Object    args        System out printf format  args       Alternatively  you can just use a static import if you want to type as little as possible  Then you don t have to create your own method   import static java lang System out   out printf  Numer of apples   d   10

User · Answer

You could write a convenience method   public PrintStream print String format  Object    arguments        return System out format format  arguments       But as you can see  you ve simply just renamed format  or printf    Here s how you could use it   private void printScores Player    players        for  int i   0  i  lt  players length    i            Player player   players i           String name     player getName            int    score    player getScore               Print name and score followed by a newline         System out format   s   d n   name  score               Print a single player  3 players  and all players printScores player1   System out println    printScores player2  player3  player4   System out println    printScores playersArray       Output Abe  11  Bob  22 Cal  33 Dan  44  Abe  11 Bob  22 Cal  33 Dan  44   Note there s also the similar System out printf method that behaves the same way  but if you peek at the implementation  printf just calls format  so you might as well use format directly    Varargs PrintStream format String format  Object    args  PrintStream printf String format  Object    args

User · Answer

The variable arguments must be the last of the parameters specified in your function declaration  If you try to specify another parameter after the variable arguments  the compiler will complain since there is no way to determine how many of the parameters actually belong to the variable argument   void print final String format  final String    arguments        System out format  format  arguments

User · Answer

You can pass all similar type values in the function while calling it  In the function definition put a array so that all the passed values can be collected in that array  e g      static void demo  String     stringArray      your code goes here where read the array stringArray

User · Answer

This is just an extension to above provided answers    There can be only one variable argument in the method  Variable argument  varargs  must be the last argument    Clearly explained here and rules to follow to use Variable Argument

[java] How can I create a Java method that accepts a variable number of arguments?

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