Can a method throw java.lang.Exception without declaring it in Java?

No, to explicitly throw any exception, you need to create an object of the exception and throw it using the throw keyword.

If you do not create an object, you cannot explicitly throw an exception, and you may create a scenario that causes the corresponding exception.

Example

The following Java program throws NullPointerException

public　class　ExceptionExample　{
　　　public　static　void　main(String[]　args)　{
　　　　　　System.out.println("Hello");
　　　　　　NullPointerException　nullPointer　=　new　NullPointerException();
　　　　　　throw　nullPointer;
　　　}
}

Output Result

Hello
Exception　in　thread　"main"　java.lang.NullPointerException
　　　at　MyPackage.ExceptionExample.main(ExceptionExample.java:6)