如何将数组列表的数据从一个类迁移到另一个类

Question

So i have my an ERDBUILDER.java class is a drawing panel which allows me to draw shapes that are stored inside an arraylist Connection . I would liked to access this arraylist from another class SQL.java and create my sql statement based on the arraylist. I've tried the codes that follows but i don't know how the main class should be. I've tried to put new SQL(); in the main class but it's opening another ERDBUILDER.java class and that not what i want it to do. So how can i run this, how the main class should be?

EDITED Anyone can help?

 package project; import java.awt.Shape; import java.util.ArrayList; import project.ERDBUILDER.DrawingBoard.Attribute; import project.ERDBUILDER.DrawingBoard.Connection; import project.ERDBUILDER.DrawingBoard.Connection2; import project.ERDBUILDER.DrawingBoard.NamedShape; public class SQL { public static void main(String args[]){ ArrayList<Connection> con = new ArrayList<>(); for (int a = 0; a < con.size(); a++) { NamedShape f = con.get(a).getNamedShape1(); Attribute g = con.get(a).getNamedShape2(); String i = f.getName(); String j = g.getName(); Shape y = f.getShape(); Shape y1 = g.getShape(); System.out.println(i + " AND " + j + " are linked"); } } } 

Answer 1

Create an instance of the class where you want to create the SQL statement and pass the Connection ArrayList to that class.

List<Connection> con = new ArrayList<>();
ERDBuilder x = new ERDBuilder(con);

Your ERDBuilder constructor can take a List object and use it to build a SQL statement. Or you can even do this in a method of ERDBuilder. That is your choice.

ERDBuilder x = new ERDBuilder();
List<Connection> con = new ArrayList<>();
x.buildSql(con);

If you want to do it from main then you have to declare the List as a Class level variable, the same way you have done with the ERDBuilder.