Learning Java: How to make a short alias for System.out.println()

I would like to make an alias of or an extended version of System.out.println() for printing my variables of various types. How does one pass an argument with unknown type/class to a method?

public static void p(VariableType... args) {
    Syst开发者_JAVA百科em.out.println(args[0]);
    // ...
}

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You can use Object.

public static void p(Object... args) {
  System.out.println(args[0]);
  // ...
}

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Unless you want lots of lines in the output, you could do.

public static <PrintableToString> void p(PrintableToString... args) {
    for(PrintableToString pts: args)
        System.out.print(pts);
    System.out.println();
}

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How about this:

public static <T> void p(T... args)
{
    System.out.println(args[0]);
    // ...
}

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Others have answered your question.

I'd just like to point out that your p method is a bad style and (probably) a bad idea:

1. The method name p doesn't tell anyone what it does.

2. Writing to standard output is usually a bad idea. The exception is when the application is designed to be run as a command line utility.

3. Even if it is right to write to standard output, doing it that way is limiting your ability to reuse your code. A better approach is to make the stream a parameter; e.g.

   public void outputFoo(Foo foo, PrintStream ps) {
       ps.println("Foo's bar is " + foo.bar);
       // ...
   }
   

4. If the p method is going to be used for trace prints, then using your p wrapper rather than System.err.println will hide the traceprints from style checkers like PMD. You might think this is a good thing, but in fact it is a bad thing, because now PMD won't remind you to remove the trace prints before you put your code into production / ship it to customers.

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Simply use Object, because Object is the type of all Java variables.

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Here's a very simple solution, which works for all my use cases:

public static final void print(Object x) { System.out.println(x); }