List Improvements in Java 9 with JShell

1. The arrival of Java 9 brings many new features to Java’s Collections API, one of which being collection factory methods. Java 9 has created factory methods for creating immutable Lists, Sets, Maps, and Map.Entry Objects
2. In older versions in Java, like Java 8 and earlier versions, we can use Collections class utility methods like unmodifiableXXX to create Immutable Collection objects for our requirements. If we want to create an Immutable List, then we can use Collections.unmodifiableList method. Same can be applied with Set and Map.
3. These methods are too long and more detailed. In order to achieve the same behavior, Java 9 has provided utility methods to List, Set and Map interfaces.


Advantages:
1. These lists are immutable. Elements cannot be added, removed, or replaced in these lists. Calling any mutator method (i.e. add, addAll, clear, remove, removeAll, replaceAll) will always cause UnsupportedOperationExceptionto be thrown.
2. They do not allow null elements. Attempts to add null elements result in NullPointerException.
3. They are serializable if all elements are serializable.
4. The order of elements in the list is the same as the order of the provided arguments, or of the elements in the provided array.

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Please watch: "What is JShell ? | Practical explanation of JShell | Java 9 feature JShell | JShell | REPL"
https://www.youtube.com/watch?v=T-e1EnKgWq0
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