我正在编写一个存储对象的程序ArrayList
(Person
输入来自文本文件)。
这是Person
该类的代码,我将从以下位置创建Person
对象:
import java.io.Serializable;
public class Person implements Comparable<Person>, Serializable
{
private String firstName;
private String lastName;
private int age;
public Person(String firstName, String lastName, int age)
{
this.firstName = firstName;
this.lastName = lastName.toUpperCase();
this.age = age;
}
public int getAge()
{
return age;
}
public String getName()
{
return firstName;
}
/**
* @return a String of the details of a person in the format:
* Name: <firstName> <lastName> Age: <age>
*/
public String toString()
{
return
"Name: " + firstName + "" + lastName + "\t\t" + "Age: " + age;
}
/**
* Compare the age of the current instance of Person to another age of the specified Person
* @return negative number this < p
* @return 0 if this == p
* @return positive number if this > p
*/
public int compareTo(Person p) {
return ((Integer)this.getAge()).compareTo(p.getAge());
}
我创建了一个Comparable
界面:
public interface Comparable<T> {
public int compareTo(T o);
}
这里是调用类的代码Collection
,它将创建一个ArrayList
存储Person
对象,我省略了部分不相关的代码,因为它很长:
import java.io.*;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.StringTokenizer;
import java.util.Iterator;
public class Collection
{
private ArrayList<Person> people;
public Collection()
{
people = new ArrayList<Person>();
}
public void readFromFile(String filename)
{
// code that will get input to assign values to fields to a Person
Person newPerson = new Person(firstNameToken, lastNameToken, ageToken);
}
/**
* Prints the details of each person held in the people ArrayList
*/
public void printDetails()
{
Iterator<Person> it = people.iterator();
while(it.hasNext())
{
Person p = it.next();
System.out.println(p.toString());
}
}
public static void main(String [] args) throws FileNotFoundException
{
Collection c = new Collection();
// check
//for(Person person : c.people)
//{
// System.out.println(person);
//}
Collections.sort(c.people);
}
}
但是我收到此错误,排序不起作用:
线程“main”java.lang.Error 中的异常:未解决的编译问题:绑定不匹配:Collections 类型的泛型方法 sort(List) 不适用于参数 (ArrayList)。推断类型 Person 不是有界参数的有效替代 >
有谁知道为什么?我在谷歌上疯狂地寻找解决方案,我看不到我错过了什么。我已经实现了可比较的..