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

------解决方案--------------------
IO包

------解决方案--------------------
Systems是java.lang包中的一个类，out是其中的一个静态变量，public的

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public static final PrintStream out

   The "standard" output stream. This stream is already open and ready to accept output data. Typically this stream corresponds to display output or another output destination specified by the host environment or user.

   For simple stand-alone Java applications, a typical way to write a line of output data is:

            System.out.println(data)
       

   See the println methods in class PrintStream.

   See Also:
       PrintStream.println(), PrintStream.println(boolean), PrintStream.println(char), PrintStream.println(char[]), PrintStream.println(double), PrintStream.println(float), PrintStream.println(int), PrintStream.println(long), PrintStream.println(java.lang.Object), PrintStream.println(java.lang.String)



------解决方案--------------------
输入具体怎么操作

------解决方案--------------------
System是java.lang中的一个类，这个类中的一个静态对象是out，拥有输出的能力