Java - Streams: Difference between revisions
Line 33: | Line 33: | ||
student = (Student)(iterator.next()); | student = (Student)(iterator.next()); | ||
System.out.println(student.getFullName()); | System.out.println(student.getFullName()); | ||
} | |||
</source> | |||
===Autoboxing=== | |||
is the process of performing the encapsulation before a primitive is stored in a collection, and the following is an example of how this can improve your code: | |||
<source lang="Java"> | |||
Random random = new Random(); | |||
Collection<Integer> collection = new ArrayList<Integer>(); | |||
for (int i = 0; i < 10; i++) { | |||
collection.add(random.nextInt()); | |||
} | |||
</source> | |||
===Unboxing=== | |||
is the process of extracting the primitive value from its corresponding wrapper object when retrieving data from a collection: | |||
<source lang="Java"> | |||
int total = 0; | |||
Iterator<Integer> iterator = collection.iterator(); | |||
while (iterator.hasNext()) { | |||
total += iterator.next(); | |||
} | } | ||
</source> | </source> |
Revision as of 17:10, 18 October 2019
Collections
Main Methods
<source lang="Java"> - add(Object o) //Adds the specified object to the collection. - remove(Object o) //Removes the specified object from the collection. - clear() //Removes all elements from the collection. - size() //Returns an integer that indicates how many elements are currently in the collection. - iterator() //Returns an object that can be used to retrieve references to the elements in the collection. </source>
Samples
Print all Students name
<source lang="Java"> Student student; Iterator iterator = collection.iterator(); while (iterator.hasNext()) {
student = (Student)(iterator.next()); System.out.println(student.getFullName());
} </source>
Get a Student
<source lang="Java"> Student student = getNextStudent(); while (student != null) {
collection.add(student);
} </source>
Iteration Without Generics Often Requires Casting
<source lang="Java"> Student student; Iterator iterator = collection.iterator(); while (iterator.hasNext()) {
student = (Student)(iterator.next()); System.out.println(student.getFullName());
} </source>
Autoboxing
is the process of performing the encapsulation before a primitive is stored in a collection, and the following is an example of how this can improve your code: <source lang="Java"> Random random = new Random(); Collection<Integer> collection = new ArrayList<Integer>(); for (int i = 0; i < 10; i++) {
collection.add(random.nextInt());
} </source>
Unboxing
is the process of extracting the primitive value from its corresponding wrapper object when retrieving data from a collection: <source lang="Java"> int total = 0; Iterator<Integer> iterator = collection.iterator(); while (iterator.hasNext()) {
total += iterator.next();
} </source>
A voir
- Parallel stream