Generic class ArrayList min/max values

Posted 13 March 2014 - 09:58 AM

The assignement is to write a Generic class<T> that has an add method to add the values of Number type to an ArrayList. Then write a largest and smallest method to determine the largest and smallest numbers in the ArrayList.

The problem i am having is that when i run the program it only compares the first two numbers of the ArrayList and does not factor in the rest.

import java.util.ArrayList;

public class JEB_003_001<T extends Number> {
	ArrayList<T> al = new ArrayList<T>();
public void add(T number){
	al.add(number);
}
public T largest(){
	T large = al.get(0);
	for (int i = 0; i < al.size(); i++){
		if(al.get(i).toString().compareTo(large.toString()) > 0)
			large = al.get(i);
	}
	return large;
}
public T smallest(){
	T small = al.get(0);
	for(int i=0; i < al.size(); i++){
		if(al.get(i).toString().compareTo(small.toString()) < 0)
			small = al.get(i);
	}
	return small;
}
public void display(){
	System.out.println(al);
}
}

and my driver is

public class JEB_003_001_002 {
	
	public static void main(String args[]){ 
		JEB_003_001<Number> list = new JEB_003_001<Number>();
		list.add(7);
		list.add(-9);
		list.add(23);
		list.add(18);
		list.add(12);
				
		System.out.println("The numbers from the list are: ");
		list.display();
			
		Number largest = list.largest();
		System.out.println();
		System.out.println("The largest number from the list is: " + largest);
		
		Number smallest = list.smallest();
		System.out.println();
		System.out.println("The smallest number in the list is: " + smallest);
	}

}