我试图实例化一个String类型的List,当我有这个时;
List<String> names = new ArrayList<String>();
我收到编译时错误,说这些类型不兼容,但据我所知,这是你应该如何实例化List。
这是全班。
package listDriver;
import list.*;
/**
* Test the List ADT.
*
* @author (sdb)
* @version (Jan 2012)
*/
public class HomeworkArrayListDriver
{
public static void main()
{
List <String> names = new ArrayList<String>();
System.out.println ("Testing ArrayLists");
//names = new ArrayList <String> ();
names.add ("jim");
names.add ("mary");
names.add ("joe");
names.add ("sue");
System.out.println (names.get(2)); // Should be joe
names.set (2, "Joe");
System.out.println (names.get(2)); // Should be Joe
System.out.println (names.size()); // Should be 4
names.remove (0);
System.out.println (names.size()); // Should be 3
names.add(0,"joe");
System.out.println (names.size()); // Should be 4
System.out.println (names.get(3)); // Should be sue
if (names.isEmpty())
System.err.println ("Incorrect, error in isEmpty");
names.clear();
if (!names.isEmpty())
System.err.println ("Incorrect, error in isEmpty or clear");
}
}
答案 0 :(得分:1)
我怀疑你的进口是错误的。
import java.util.List;
import java.util.ArrayList;
public class Main {
public static void main(String... args) {
List<String> list = new ArrayList<>();
list.add("3")
System.out.println(list);
}
}
答案 1 :(得分:-1)
在ArrayList
包中设置list
课程,在List
包中实施list
课程。