英文:
How do I fix implementation error in JAVA VS code, "must implement the inherited abstract class"
问题
我目前正在学习接口、类和泛型。
我的当前任务是创建一个类，模拟 Java 中的 "ArrayLists"（可能是 Java 7）。
这是接口：1
我已经创建了一个类：
public class StudentArrayList implements SimpleArrayList<E> {
但是我遇到了这个错误：我遇到了这个错误
错误：StudentArrayList 类必须实现继承的抽象方法 SimpleArrayList<E>.set(int, E)Java(67109264)
我已经在类中实现了所有的函数签名，但它仍然要求我一遍又一遍地实现。我该如何解决这个问题？请告诉我。谢谢！
StudentArrayList.java:
public class StudentArrayList implements SimpleArrayList<E> {
public static void main(String[] args) {
System.out.println("Success");
}
@Override
public int size() {
// TODO Auto-generated method stub
return 0;
}
@Override
public boolean isEmpty() {
// TODO Auto-generated method stub
return false;
}
// ... 其他函数实现 ...
@Override
public E get(int index) {
// TODO Auto-generated method stub
return null;
}
@Override
public void set(int index, E element) {
// TODO Auto-generated method stub
}
// ... 其他函数实现 ...
}
英文:
I am currently learning interfaces, classes and generics.
My current assignment is to create a class which mimics "ArrayLists" in Java. (probably java 7)
I have created a class:
public class StudentArrayList implements SimpleArrayList<E> {
but I am getting this error: I am getting this error
Error: The type StudentArrayList must implement the inherited abstract method SimpleArrayList<E>.set(int, E)Java(67109264)
I have already implemented all the function signatures in the class, but it is still me asking to implement again and again.
How do I fix this issue? please let me know.
Thanks!
StudentArrayList.java:
public class StudentArrayList implements SimpleArrayList<E> {
public static void main(String[] args) {
System.out.println("Success");
}
@Override
public int size() {
// TODO Auto-generated method stub
return 0;
}
@Override
public boolean isEmpty() {
// TODO Auto-generated method stub
return false;
}
@Override
public boolean contains(E o) {
// TODO Auto-generated method stub
return false;
}
@Override
public E[] toArray() {
// TODO Auto-generated method stub
return null;
}
@Override
public void add(E e) {
// TODO Auto-generated method stub
}
@Override
public void remove(E o) {
// TODO Auto-generated method stub
}
@Override
public boolean containsAll(SimpleArrayList<E> c) {
// TODO Auto-generated method stub
return false;
}
@Override
public boolean addAll(SimpleArrayList<E> c) {
// TODO Auto-generated method stub
return false;
}
@Override
public boolean addAll(int index, SimpleArrayList<E> c) {
// TODO Auto-generated method stub
return false;
}
@Override
public boolean removeAll(SimpleArrayList<E> c) {
// TODO Auto-generated method stub
return false;
}
@Override
public boolean retainAll(SimpleArrayList<E> c) {
// TODO Auto-generated method stub
return false;
}
@Override
public void clear() {
// TODO Auto-generated method stub
}
@Override
public E get(int index) {
// TODO Auto-generated method stub
return null;
}
@Override
public void set(int index, E element) {
// TODO Auto-generated method stub
}
@Override
public void add(int index, E element) {
// TODO Auto-generated method stub
}
@Override
public void remove(int index) {
// TODO Auto-generated method stub
}
@Override
public int indexOf(E o) {
// TODO Auto-generated method stub
return 0;
}
@Override
public int lastIndexOf(E o) {
// TODO Auto-generated method stub
return 0;
}
@Override
public SimpleArrayList subList(int fromIndex, int toIndex) {
// TODO Auto-generated method stub
return null;
}
}`
答案1
得分: 1
你似乎正在尝试编写一个实现通用接口的通用类。问题在于你实际上并没有将这个类声明为通用类。因此编译器认为 E 是一个类名。
原始声明：
public class StudentArrayList implements SimpleArrayList<E> {
应改为：
public class StudentArrayList<E> implements SimpleArrayList<E> {
StudentArrayList 后面的 <E> 将 E 声明为 StudentArrayList 的类型参数。
编译错误可能是由于编译器错误地将 E 视为类名（而不是类型参数），并且无法找到任何关于它的定义。
英文:
You appear to be trying to write a generic class that implements an generic interface. The problem is that you have not actually declared the class as generic. And the compiler therefore things that E is a class name.
The declaration:
public class StudentArrayList implements SimpleArrayList<E> {
should be:
public class StudentArrayList<E> implements SimpleArrayList<E> {
The <E> after StudentArrayList declares E as a type parameter of StudentArrayList.
The compilation errors were probably a result of the compiler thinking that E was a class name (rather than a type parameter) and not being to find any definition for it.
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