泛型类型通配符?的使用

package com.china.hc;

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

public class GenericMethodTest03 { // 泛型类型通配符?

	public static void main(String[] args) {
		List<String> name = new ArrayList<String>();
		List<Integer> age = new ArrayList<Integer>();
		List<Number> number = new ArrayList<Number>();
		name.add("my name is hc");
		age.add(24);
		number.add(12);
		
		getData(name);
		getData(age);
		getData(number);
		
	}
	
	public static void getData (List<?> data) {
		System.out.println(data.get(0));
	}

}