The compiler will simply emit an unchecked conversion warning, because it doesn't know if the cast is safe or not.

编译器仅仅发出一个类型未检查转换警告，因为它不知道这种转换是否安全。

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Unchecked generic type operation The compiler will issue an error or warning whenever it encounters an unchecked generic type operation.

Unchecked generic type operation编译器每当遇到未经检查的泛型类型操作，就将发出一个错误或者警告。

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Similarly, instanceof checks on naked type parameters will result in an "unchecked" warning at compile time and the check will not occur as expected at runtime.

同样，对“外露”类型参数的instance of检查将在编译时产生“unchecked”警告，而且检查将不会如期在运行时进行。

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As McCain tries to gain ground in the final week of campaigning, he's been warning voters that an Obama win would mean an unchecked Democratic Congress.

CNN: Obama takes swipe at McCain adviser's health care comment