指向另一個文件中的內部類時找不到符號

Question

因此，我正在處理此項目，並且需要爲它創建自己的ArrayList類。我已經定義了所有的方法，但是當我編譯時，我一直在爲我的三個方法收到「無法找到符號」錯誤。我有一個如下界面：

public interface FBList { 

    public int size(); 

public void insert(int i, Person person); 

public Person remove(int i); 

public Person lookUp(int i); 

/** 
*A class that defines a person 
**/ 
public class Person { 
    private String id; 
    private long phoneNum; 

    public Person(String personID, long phoneNum){ 
     id = personID; 
     phoneNum = phoneNum; 
    } 
} 

正如你所看到的，我有一個內部類。我試圖在我的其他文件中使用該類實現此接口。目前，有三種方法在我的其他文件給我的問題如下：

/** 
    * A method to expand the size of the array if the array is too small 
    * @param i One minus the place in the list where the component will be inserted 
    * @param Person The person to be put in the list 
    **/ 
    protected void expandInsert(int i, Person person){ 
     Person[] temp = new Person[arrayList.length * 2]; 
     for(int index = 0; index < temp.length; index++){ 
      if(i != index){ 
       if(i > 0) 
        temp[index] = arrayList[index]; 
       if(i == 0) 
        temp[index + 1] = arrayList[index]; 
      } 
      else{ 
       temp[i] = person; 
       i = 0; 
       index--; 
      } 
     } 
     arrayList = temp; 
    } 

/** 
    * Inserts a new component at the end of a list by creating a new list longer that then last 
    * @param i The place in the list where the component will be inserted 
    * @param Person The person to be added to the list 
    **/ 

protected void insertAtEnd(int i, Person person){ 
    Person[] temp = new Person[arrayList.length + 5]; 
    for(int index = 0; index < temp.length; index++){ 
     if(index != i){ 
      temp[index] = arrayList[index]; 
     } 
     else{ 
      temp[index] = person; 
     } 
    } 
    arrayList = temp; 
} 

/** 
* Shrinks the array by one by removing one component from the array 
* @param i The index to be removed 
**/ 

protected void shrink(int i){ 
    Person[] temp = new Person[arrayList.length - 1]; 
    for (int index = 0; index < arrayList.length ; index++) { 
     if (index < i) { 
      temp[index] = arrayList[index]; 
     } 
     else if (index == i){ 
      removedPerson = arrayList[index]; 
      temp[index] = arrayList[index + 1]; 
     } 
     else{ 
      temp[index - 1] = arrayList[index]; 
     } 
    } 
} 

所有這些文件都在同一個文件夾，所以不應該出現的問題。我正在使用終端鍵入「javac FBArrayList.java」進行編譯。我的編譯器的輸出是這樣的：

FBArrayList.java:106: cannot find symbol 
symbol : method expandInsert(int,FBList.Person) 
location: class FBList.Person[] 
      arrayList.expandInsert(i, person); 
        ^
FBArrayList.java:108: cannot find symbol 
symbol : method insertAtEnd(int,FBList.Person) 
location: class FBList.Person[] 
      arrayList.insertAtEnd(i, person); 
        ^
FBArrayList.java:118: cannot find symbol 
symbol : method shrink(int) 
location: class FBList.Person[] 
     arrayList.shrink(i); 
       ^
3 errors 

Answer 1

由於Person是一個內部類，它的名字必須是合格與外部類的名稱：

protected void expandInsert(int i, FBList.Person person){ 
    FBList.Person[] temp = new FBList.Person[arrayList.length * 2]; 
    ... 
    // and so on... 
} 

編輯：刪除一個因爲該類嵌套在接口內，所以建議使用類static。嵌套在類內部的類需要這個建議;對於接口，static是可選的。