空指针异常将决不会被完全根除。
Null-pointer exceptions will never be completely eradicated.
它的目的是避免使用空子符串调用 Web 服务而出现空指针异常。
This code is included in the code which handles the click event for the Invoke Service button and its purpose is to avoid a null pointer exception when the web service is invoked with an empty string.
在许多空指针异常中，真正的错误出现在变量被赋为空值的地方。
In many null-pointer exceptions, the true bug occurs where the variable is actually assigned to null.
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