什么是泛型

public class Test<T,E>{

	public static void main(String[] args) {
	  Test<Integer,Object> aTest = new Test<>();
	  

	}
}

import java.awt.List;
import java.util.ArrayList;

public class Test{

	public static void main(String[] args) {
	  
		ArrayList list = new ArrayList();
		list.add("hellow");
		list.add("hh");
		list.add(100);
		for(Object lObject:list){
			System.out.println((String)lObject);
		}
			
	}
}