我遇到了未经检查的投射警告。我不确定如何解决警告。
编译器错误似乎挑剔了list = (E[]) new IntKeyed [size];
这是我们应该逐个字母使用的代码。
我们试图使用泛型,因此是"E"。
所以我想我一定在这个代码的某个地方搞砸了。当我查找错误时,它似乎处理了ArrayLists
,但我没有使用我的知识ArrayList
。
也许我应该ArrayLists
?更改它会修复警告吗?我的代码中也有不完整的异常处理问题。但我认为这与阵列问题无关。
你能找到的任何错误都将有助于为我指明正确的方向。谢谢。
public abstract class MyArrayList<E> implements IntKeyed
{
private final int DEFCAP = 50;
private int origCap;
private int numElements;
private E[] list;
public MyArrayList()
{
origCap = DEFCAP;
list = (E[]) new IntKeyed [origCap]; *******Error Here
}
public MyArrayList( int size ) throws Exception
{
size = DEFCAP;
if( size > 0 )
{
list = (E[]) new IntKeyed [size]; *******Error Here
origCap = size;
}
else
{
throw new ArrayStoreException();
System.out.println("List size is invalid");
}
list = (E[]) new IntKeyed [size]; *******Error Here
}
private void enlarge ()
{
E[] larger = (E[]) new IntKeyed [list.length + origCap]; *******Error Here
for( int i = 0; i < list.length; i++)
{
larger[i] = list[i];
}
list = larger;
}
使用 javac -Xlint:unchecked MyArrayList.java
编译时我得到:
MyArrayList.java:29: warning: [unchecked] unchecked cast
list = (E[]) new IntKeyed [origCap];
^
required: E[]
found: IntKeyed[]
where E is a type-variable:
E extends Object declared in class MyArrayList
MyArrayList.java:37: warning: [unchecked] unchecked cast
list = (E[]) new IntKeyed [size];
^
required: E[]
found: IntKeyed[]
where E is a type-variable:
E extends Object declared in class MyArrayList
MyArrayList.java:45: warning: [unchecked] unchecked cast
list = (E[]) new IntKeyed [size];
^
required: E[]
found: IntKeyed[]
where E is a type-variable:
E extends Object declared in class MyArrayList
MyArrayList.java:117: warning: [unchecked] unchecked cast
E[] larger = (E[]) new IntKeyed [list.length + origCap];
^
required: E[]
found: IntKeyed[]
where E is a type-variable:
E extends Object declared in class MyArrayList
MyArrayList.java:43: error: unreachable statement
System.out.println("List size is invalid");
^
1 error
4 warnings
警告不是问题,问题是抛出异常后无法访问的语句。
应该是这样的:
System.out.println("List size is invalid");
throw new ArrayStoreException();
如果您认为您的强制转换应该有效 - 在方法或语句级别添加@SuppressWarnings("unchecked")
(范围越小越好)。编译器不会发出任何消息,但如果强制转换错误,您仍然会在运行时收到异常。
list = (E[]) new IntKeyed [origCap];
警告实际上意味着通用E
被硬编码为IntKeyed
,因此无论您传递E
什么,您的list
都将始终保持为IntKeyed
类型。
在您的情况下,通用用法似乎不适合,因为您已经为此目的实现了特定的接口。