Is there any way to get input from a Scanner without declaring it?

Usually you would declare an input Scanner with Scanner scan = new Scanner(System.in);

Is there any way to use a method in the Scanner such as nextInt() or nextLine() without making an object of the class?

You could create a utility class, create static methods in that utility class and use a import static for methods in the utility class. Static method import allows you to use methods from a class without having to explicitly use the class. See the reference here.

File TestApp.java

package com.example;

import static com.example.utils.ConsoleReader.nextInt;
// Or use "import static com.example.utils.ConsoleReader.*;" if you want to import every static methods in class "ConsoleReader"

public class TestApp {

	public static void main(String[] args) {
		System.out.println("Enter the number the number");
        // The following line calls the method of the class "ConsoleReader" without having to reference it.
		int input = nextInt();
		System.out.println("You have entered " + input);
	}

}

File ConsoleReader.java

package com.example.utils;

import java.util.Scanner;

public class ConsoleReader{
	private static Scanner scan = new Scanner(System.in);
	
	public static int nextInt() {
		return scan.nextInt();
	}

    public static String nextLine() {
		return scan.nextLine();
	}
}

You could create a static class which returns the desired variable type.

For example, if you wanted to create your own class for reading the next integer:

public static int nextInt(){
    Scanner scanner = new Scanner(System.in);
    return scanner.nextInt();
}

However in reality you still have to declare it.

Then you can simply put nextInt() in your code to get the next Integer.