Which of the following Java code snippets gives a compilation error?Group of answer choicesclass MyClass<T extends Number & Comparable<T>> { // ...}class MyClass<T extends String> { public void add(T item) { // ... }}class MyClass<T> { public void add(T item) { // ... }}class MyClass<T super Number> { // ...}
Question
Which of the following Java code snippets gives a compilation error?Group of answer choicesclass MyClass<T extends Number & Comparable<T>> { // ...}class MyClass<T extends String> { public void add(T item) { // ... }}class MyClass<T> { public void add(T item) { // ... }}class MyClass<T super Number> { // ...}
Solution
The Java code snippet that gives a compilation error is:
class MyClass<T super Number> { // ... }
This is because in Java, you cannot use the super keyword in a generic type parameter declaration. The super keyword is used to refer to the superclass (parent class) of an object. In generics, you can only use the extends keyword to specify an upper bound for a type parameter, not super.
The other three code snippets are valid in Java. The first one declares a generic class with a type parameter that must be a subclass of Number and implement the Comparable interface. The second one declares a generic class with a type parameter that must be String, and the third one declares a generic class without any restrictions on the type parameter.
Similar Questions
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