system.out

问题 Is this static println function in out class from System namespace? namespace System { class out { static println ... } How can I interpret this name? And where in JRE this function is defined? In java.lang.System / java.lang.Object ? 回答1: No. Actually out is a static member in the System class (not as in .NET), being an instance of PrintStream . And println is a normal (overloaded) method of the PrintStream class. See http://download.oracle.com/javase/6/docs/api/java/lang/System.html#out.

问题 I\'m trying to understand the difference, and benefits of using System.out.println() vs. return blah in a method. It seems like System.out.println() is used to display static information, and return is a value returned from the method. Yet I\'m seeing examples like the one below, where a function is used within the System.out.println() statement System.out.println(name.substring(1, 3)); When is it right to use System.out.println() and return . Is it that return can be used by another piece of

问题 I have worked with Java for a quite a long time, and I was wondering how the function System.out.print() works. Here is my doubt: Being a function, it has a declaration somewhere in the io package. But how did Java developers do that, since this function can take in any number of arguments and any argument types no matter how they are arranged? e.g: System.out.print(\"Hello World\"); System.out.print(\"My name is\" + foo); System.out.print(\"Sum of \" + a + \"and \" + b + \"is \" + c); System

问题 How can I make Java print \"Hello\" ? When I type System.out.print(\"Hello\"); the output will be Hello . What I am looking for is \"Hello\" with the quotes( \"\" ). 回答1: System.out.print("\"Hello\""); The double quote character has to be escaped with a backslash in a Java string literal. Other characters that need special treatment include: Carriage return and newline: "\r" and "\n" Backslash: "\\\\" Single quote: "\'" Horizontal tab and form feed: "\t" and "\f" The complete list of Java