为什么我们不能在PrintStream类的帮助下调用'println（）'方法，其中out是这个类的对象？

Question

Why we can't call println() method with help of PrintStream class where out is object of this class?

import java.io.*;

class Demo {
    public static void main(String[] args) {
        PrintStream.out.println("Hello");
    }
}

Answer 1

Why we can't call println() method with help of PrintStream class where out is object of this class:

  PrintStream.out.println("Hello"); 

Three reasons:

a) it's not static - you need an instance of the PrintStream class

b) it's got protected visibility - so its not accessibe.

c) the out variable is actually an OutputStream - so it doesn't have a println method.

To use a PrintStream, you want to do something like this:

final PrintStream ps = new PrintStream(new FileOutputStream(new File(filename)));
ps.println("Now is the time for all good men to come to the aid of their party.");
ps.close();

Consult the Javadoc for more information.

Answer 2

Yep what Greg says. Also if you want to print to the console you can just use System.out.println("Manga Bunga");

And if you want to use PrintStream use the println() method after instantiating a PrintStreat object.