Main.java Source code

Introduction

Here is the source code for Main.java

Source

//package com.java2s;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Collection;

public class Main {
    /**
     * Synchronises the addition of an object to a many2many relationship. For example, if you have: 
     * Product.orders and Order.products, you can implement:
     * 
     * <pre>boolean Product.addOrder( Order prod )</pre>
     * 
     * as: 
     * 
     * <pre>return addManyToMany ( this, order, "addProduct", this.orders ); // or this.getOrders()</pre>
     *  
     * where this.orders is the set internal to Product that backs the corresponding
     * relation. This call invokes this.orders.add ( order ) and, in case this operation returns true (i.e., the order
     * was not already inside the collection), it invokes order.addProduct ( this ) too. 
     * 
     * You should implement Order.product() in a dual way. The check that the element was added to the set avoids 
     * infinite loops. 
     *  
     * @param obj the object to which added is added
     * @param added the added object
     * @param inverseRelationAddMethod the name of the method to be called to add obj to added, using the inverse side of 
     * the relation obj-added relation.
     * @param internalCollection the collection for the side from obj to added to which added is actually added
     * @return true if the added was really added to obj.
     */
    public static <O, A> boolean addMany2Many(O obj, A added, String inverseRelationAddMethod,
            Collection<A> internalCollection) {
        Exception theEx = null;
        try {
            if (!internalCollection.add(added))
                return false;
            Method inverseAdder = added.getClass().getMethod(inverseRelationAddMethod, obj.getClass());
            inverseAdder.invoke(added, obj);
        } catch (NoSuchMethodException ex) {
            theEx = ex;
        } catch (SecurityException ex) {
            theEx = ex;
        } catch (IllegalAccessException ex) {
            theEx = ex;
        } catch (IllegalArgumentException ex) {
            theEx = ex;
        } catch (InvocationTargetException ex) {
            theEx = ex;
        } finally {
            if (theEx != null)
                throw new IllegalArgumentException("Internal error: " + theEx.getMessage(), theEx);
        }
        return true;
    }
}