我想要继承一个ArrayList类 于是写了下面的代码:import java.util.*;class Dog{
private int dnumber;
Dog(int i){
dnumber=i;
}
public String toString(){
return "This Dog Number: "+dnumber;
}
}class DogList extends ArrayList{
}public class temp{
public static void main(String[] args){
DogList<Dog> d=new DogList<Dog> ();
}
}
然后就出现了下面编译异常提示:
temp.java:20: type DogList does not take parameters
DogList<Dog> d=new DogList<Dog> ();
^
temp.java:20: type DogList does not take parameters
DogList<Dog> d=new DogList<Dog> ();
^
为什么说DogList类型不能用参数
这DogList是继承自ArrayList,搞不明白错在哪里了如果是这样的话,就没有任何问题了,代码如下:import java.util.*;class Dog{
private int dnumber;
Dog(int i){
dnumber=i;
}
public String toString(){
return "This Dog Number: "+dnumber;
}
}
public class temp{
public static void main(String[] args){
ArrayList<Dog> a=new ArrayList<Dog>();
}
}
哪位高手能指点一下?
private int dnumber;
Dog(int i){
dnumber=i;
}
public String toString(){
return "This Dog Number: "+dnumber;
}
}class DogList extends ArrayList{
}public class temp{
public static void main(String[] args){
DogList<Dog> d=new DogList<Dog> ();
}
}
然后就出现了下面编译异常提示:
temp.java:20: type DogList does not take parameters
DogList<Dog> d=new DogList<Dog> ();
^
temp.java:20: type DogList does not take parameters
DogList<Dog> d=new DogList<Dog> ();
^
为什么说DogList类型不能用参数
这DogList是继承自ArrayList,搞不明白错在哪里了如果是这样的话,就没有任何问题了,代码如下:import java.util.*;class Dog{
private int dnumber;
Dog(int i){
dnumber=i;
}
public String toString(){
return "This Dog Number: "+dnumber;
}
}
public class temp{
public static void main(String[] args){
ArrayList<Dog> a=new ArrayList<Dog>();
}
}
哪位高手能指点一下?
private int dnumber;
public Dog(int i) {
this.dnumber = i;
} public String toString() {
return "This Dog Number: " + this.dnumber;
} public static void main(String[] args) {
DogList<Dog> d = new DogList<Dog>();
Dog dog = new Dog(13);
d.add(dog);
System.out.println(d.get(0).toString());
}
}class DogList<T> extends ArrayList<T> {
private static final long serialVersionUID = 1L;
}