"class, interface, or enum expected" error when trying to create package

I'm trying to declare a package in a file as follows:

import java.util.*;

package rtg;

public class Generate
{
    // ...
}
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But I'm getting an error when I try to compile this:

Generate.java:3: class, interface, or enum expected package rtg;

Why am I getting this error?

it should be

package rtg;
import java.util.*;
public class Generate{
}

In java you first define package then imports and then class. See wiki here: Java_package and Oracle's tutorial here: Java Packages

Edit

Now to call Genereate class from a class in same folder that is rtg folder:

package rtg;
public class GUI{
     Generate gen = new Generate();
}

Make sure all words are spelled correctly.

The pacakge declaration must be the first thing in a Java file (apart from comments). You can't put the imports above it.

All the examples are above is good but we have to compile this package making class by swich standard ... You have to give "-d" and destinations folder for making package in it. "c: \f1 >javac -d e: \f2 temp . Java" 'c,e'are drive, 'f1,f2' are folder, temp is class name.