检查 Object 是否是 String、HashMap 或 HashMap[ ] 的实例
我在java中有一个对象。有没有办法在将对象实际转换为 String、HashMap 或 HashMap[ ] 之前检查它是否是 String、HashMap 或 HashMap[ ] 的实例？
如果没有，因为上面的方法似乎违反直觉，有没有办法将其转换为每个对象，并测试新转换的对象的某些内容，看看它是否实际上是它所转换的对象的类型？
I have an Object in java. Is there a way to check if an object is an instance of a String, HashMap, or HashMap[ ] before actually casting it to those objects?
If not, as it seems counterintuitive that the above would work, is there a way to cast it into each object, and test something about the newly casted object to see if its in fact the type of object into which it was casted?
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是的：
顺便说一下，澄清一下：
您不能将某些内容转换为无效类型。如果
obj的类型为String，则((Integer)obj)将导致在运行时引发ClassCastException-时间。Yes:
By the way, to clarify regarding this:
You cannot cast something into an invalid type. If
objhas typeString, then((Integer)obj)will cause aClassCastExceptionto be raised at run-time.您正在寻找
instanceof操作员。示例：
"Hello" instanceof String将返回true，而new Integer(5) instanceof String将返回false。You are looking for the
instanceofoperator.Example:
"Hello" instanceof Stringwould returntruewhilenew Integer(5) instanceof Stringwould returnfalse.