How to compile several classes in one ,java file

Question

I would like to compile in a java source file with two classes. How can I do that? I compile my code with:

javac -classpath Class_ex_1.java

public class Class_ex_1 { 
    public static void main(String[] args) {        
        int del = 7;
        int del_1 = 2;
        int rem = del % del_1;
        System.out.println("First value :" + del + "\n");
        System.out.println("Second value :" + del_1 + "\n"); // 
        System.out.println("Display meaning a % b :" + rem + "\n"); //              
            
        Hello_test n1 = new Hello_test();
        System.out.println("Display parameter from class:" + n1.getColor + "\n");
                        
    }
}
    
public class Hello_test {
    String color = "Red";       
    public String getColor(){
        return color;
    }           
}

Answer 1

class Hello_test{}

Simply remove public from the second class. Also make sure the other class is inside of the Class_ex_1