In addition, avoid returning objects that are null or in an invalid state.

此外，避免返回空对象或者状态无效的对象。

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If the file does not exist (as determined by the file open error), write the "null" state to the file.

如果该文件不存在(由文件打开错误确定)，则把“null”状态写入文件。

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The second parameter (state) can either be null or an object containing application-specific information.

public void TimerCallback(object state);第二个参数（state）可以为空或者是包含程序规范信息的对象。

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The lawsuit asks the court to declare the tax cap, as it applies to public schools, null and void because it violates the New York state and U.S. constitutions and to permanently block it from being applied.

WSJ: Teachers union challenges NY's property tax cap

Petersburg went awry when the Ministry of State Property there declared the venture fund's controlling position null and dismissed the idea of compensation.

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