如何检查Date参数在Java中是否具有某些值
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How to check if Date parameter has some value in Java
提问by Dragan
I'm moving from C# to java and I'm having troubles with the basics. I'm expecting a variable in my method of type Date and I need to check if the Date has been set or not. How do I do that in Java? using ,equals or == ??
我正在从 C# 转向 Java，但在基础知识方面遇到了麻烦。我期待我的 Date 类型方法中有一个变量，我需要检查 Date 是否已设置。我如何在 Java 中做到这一点？使用 ,equals 或 == ??
Thanks a lot!
非常感谢！
回答by Edwin Dalorzo
if ( myDate != null){
//do your stuff here
}
回答by Jon Skeet
I suspect you want:
我怀疑你想要：
public void foo(Date date) {
if (date != null) {
// Use date here
}
}
Note that unlike DateTimein .NET, java.util.Dateis a class (and therefore a reference type)... Java doesn't have "custom" value types.
请注意，与DateTime.NET不同的是，它java.util.Date是一个类（因此是一个引用类型）……Java 没有“自定义”值类型。
Also note that that's not quite the same as whether or not the variable has been "set". For example:
另请注意，这与变量是否已“设置”不同。例如：
Date date = new Date();
date = null;
Would you consider that variable to be "set" or not? It's set to have a null reference as its value. I suspectyou want to know whether the variable has a value referring to an object, but that's not quite the same thing.
您会认为该变量是“设置”还是不“设置”？它被设置为有一个空引用作为它的值。我怀疑您想知道变量是否具有引用对象的值，但这并不完全相同。
