Java Program to Add the Data from the Specified Collection in the Current Collection
The grouping of objects in a single unit is called a collection. For example Array, Lists, Hashsets, etc. Data can be added from a specified collection in the current collection by using the addAll() method in Java. This method falls under the header file, java.util.*. The addAll() method returns a true value if the adding of the collection is successful after calling the method else it returns a false value.
We can use the addAll() method in two ways namely:
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- The static method
- The instance method
Let there be 2 lists.
The static method Declaration
The instance method Declaration
Let the index where List2 needs to be inserted in List1 is 1.
The addAll() method always throws the following exceptions:
- NullPointerException: This exception is thrown if the specified or the current collection has null values.
- IllegalArgumentException: If the arguments of the specified collection have values that prevent them from being added to the current collection, this exception is thrown.
Input: boolean b = List1.addAll(large,extra-large) If the appending is successful Output: true If the appending is unsuccessful Output: false
Input: Collections.addAll(List1,List2) Output: List1 = [small,medium,large,extra-large]
- Initializing the two collections.
- Using the addAll() method to append the lists.
- Checking the boolean value of the method call.
- Printing the collections’ final values.
Below is the implementation of the above approach:
Initial collection value of list: [1, 2, 3] Initial collection value of list2: [4, 5, 6] Boolean Result: true Final collection value of list: [1, 2, 4, 5, 6, 3] Final collection value of list2: [4, 5, 6, 9, 8, 7, 6]