如何在代码顶部正确声明package与import语句？能否将二者同行编写？

Hey there! Let's walk through your two questions step by step, using your provided code as a starting point.

1. How to properly place a package declaration and import Scanner at the top of your code #

First off, let's clarify Java's strict rules for top-level statements:

• The package declaration must be the very first line of your code (you can only have comments before it, no actual code statements).
• All import statements need to come right after the package declaration, and before you define any classes or interfaces.

Looking at your sample code, there's a small issue with the Scanner import: import java.util.Scanner.*; is incorrect because Scanner is a specific class, not a package. You should use import java.util.Scanner; instead to import just the Scanner class, or import java.util.*; to import all classes in the java.util package.

Here's a corrected version of your code that follows these rules:

package b;
import java.util.Scanner;
import a.*;

public class Session27P1 {
    public static void main(String args[]) {
        Scanner input = new Scanner(System.in);
        System.out.println("Enter the number");
        int xc = input.nextInt();
        Frog frog1 = new Frog();
        frog1.showAge(xc);
        int year = frog1.showAge();
        System.out.println(year);
    }
}

2. Can the import statement and package declaration be written on the same line? #

Short answer: No, this is not allowed in Java.

Java's syntax requires that the package declaration is a standalone statement at the top of your file (again, only comments can precede it). If you try to combine it with an import statement on a single line, the compiler will throw an error because it expects each top-level statement (package, import) to be on its own line. This rule helps keep code readable and aligns with Java's strict structure requirements.

内容的提问来源于stack exchange，提问作者Aditya Bhogte