int sum=0;

for(int x:nums){

sum+=x;

}

return((float)sum)/nums.length;

}

public static void main(String args[]){

Calculation cal=new Calculation();

float av1=cal.avg(10,20,30);

System.out.println(av1);

}

}

10.package test;

public class OuterClass{

private class InterClass{

public InterClass(){

System.out.println(“InterClass”);

}

}

public OuterClass(){

InterClass ic=new InterClass();

System.out.println(“OuterClass”);

}

public static void main(String args[]){

OuterClass oc=new OuterClass();

}

}

11.import java.io.*;

public class FileTest{

public static void main(String args[]){

File f=new File("document","old");

File d=new File("target");

d.mkdir();

f.renameTo(new File("target","new"));

String l[]=d.list();

for(int i=0;i

System.out.println(l[i]);

}

}

12.interface ShowMessage{void显示商标(String s);}