为什么不将System.out重命名为PrintWriter？

Question

For simple laziness reasons, I get annoyed having to type the full System.out.println("..."); in Java code. Why would it be bad programming practice (if at all) to do something like this?

import java.io.PrintWriter;
public class RenameSystemOut{
    public static void main(String[] args){
        PrintWriter w = new PrintWriter(System.out);
        w.println("Hello, world");
        w.close();
    }
}

My guess is that it risks the programmer forgetting to close() the resource. But I imagine that in a long program with many print statements, you could save yourself a lot of trouble.

Answer 1

Why not use an import static :

import static java.lang.System.out;

public class App {

    public static void main(final String[] args) throws Exception {
        out.println("TEST");
    }
}

If you use a decent IDE, like one of the big 3, then you can get it to type for you, in NetBeans:

sout Tab TEST

Will produce:

System.out.println("TEST");

Incidentally, I'm not sure why you need to wrap the PrintWriter System.out in another PrintWriter ; you can just do:

PrintWriter w = System.out;

And you shouldn't call close() on stdout...

Answer 2

You could also import java.lang.System statically:

import  static java.lang.System.*;

Which would then allow you to do this:

import  static java.lang.System.*;
public class RenameSystemOut{
    public static void main(String[] args){
        out.println("Hello, world");
    }
}

Answer 3

My solution to annoying "System.out.println" calls is to put this method somewhere:

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

Since primitives will be boxed, using Object will let it print any expression.

You can of course name the method whatever you want, such as p , which is great for quick debugging statements, although be mindful of the balance between ease-of-writing and ease-of-reading.

Answer 4

You don't need that...

Just type sout and press Tab and your problem is solved in Intellij IDEA.

Answer 5

You should not rename it. There is a good reason that the method is named System.out.println(); - we know that it is a System method. Without this information, anyone who uses your PrintWriter method might assume that it is from a different import or that it is a different function than System.out.println(); . It's better coding style to leave it as is.

However, copy-pasting the line or using autocompletion will make it faster to type in, solving your original issue.

Answer 6

Why would it be bad programming practice (if at all) to do something like this?

It's bad practice because it forces anyone looking at your code later to have to understand why you needed to define 'w'. And when the answer is "because I was lazy", now you've just paid for your laziness for someone else's time. That's not only rude, but expensive.

The cost of maintaining code is much higher than the cost of developing it. After functionality, your main concern when writing code should ALWAYS be how easily it can be maintained.

Making code short by using clever "tricks" may lead to interesting stackoverflow questions and answers, but they almost always work against you in the long run.

Answer 7

From the Javadoc for PrintWriter:

From Prints formatted representations of objects to a text-output stream. This class implements all of the print methods found in PrintStream. It does not contain methods for writing raw bytes, for which a program should use unencoded byte streams. Unlike the PrintStream class, if automatic flushing is enabled it will be done only when one of the println, printf, or format methods is invoked, rather than whenever a newline character happens to be output. These methods use the platform's own notion of line separator rather than the newline character.

I recommend that use System.out.println(data) or use a variable like this:

PrintStream out = System.out;
out.println("This is my output");

By another hand, think about if you wants to create a Console application or you want to log some messages or application status. In the second case, I think that you need to use a logging framework like log4j, Java Logging API or SLF4J.