將ArrayList轉換爲數組拋出java.lang.ArrayStoreException

Question

我有一個方法convertToArray()它將ArrayList轉換爲數組。每次將一個元素添加到ArrayList時，我都想調用此方法。

public class Table extends ArrayList<Row> 
{ 
public String appArray[]; //Array of single applicant details 
public String tableArray[][]; //Array of every applicant 
/** 
* Constructor for objects of class Table 
*/ 
public Table() 
{ 
} 

public void addApplicant(Row app) 
{ 
    add(app); 
    convertToArray(); 
} 

public void convertToArray() 
{ 
    int x = size(); 
    appArray=toArray(new String[x]); 
} 

}

當我打電話的addApplication(Row app)方法我得到的錯誤：java.lang.ArrayStoreException

所以我改變了我的addApplicant()方法：

public void addApplicant(Row app) 
{ 
    add(app); 
    if (size() != 0) 
    convertToArray(); 
} 

我得到同樣的錯誤消息。任何想法爲什麼？我想，如果它在轉換之前檢查ArrayList有元素，則不應拋出該錯誤？

如果需要

Answer 1

ArrayStoreException thrown to indicate that an attempt has been made to store the wrong type of object into an array of objects.

因此，我可以提供完整的錯誤，

public Row[] appArray; // Row - because you extend ArrayList<Row> 

public void convertToArray() 
{ 
    int x = size(); 
    appArray = toArray(new Row[x]); 
}