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javanullpointerexceptiontypecasting-operator

No Exception while type casting with a null in java

String x = (String) null;

Why there is no exception in this statement?

String x = null;
System.out.println(x);

It prints null. But .toString() method should throw a null pointer exception.

Solution

  • You can cast null to any reference type without getting any exception.

    The println method does not throw null pointer because it first checks whether the object is null or not. If null then it simply prints the string "null". Otherwise it will call the toString method of that object.

    Adding more details: Internally print methods call String.valueOf(object) method on the input object. And in valueOf method, this check helps to avoid null pointer exception:

    return (obj == null) ? "null" : obj.toString();

    For rest of your confusion, calling any method on a null object should throw a null pointer exception, if not a special case.