Difference between revisions of "Iterable Immutable List Assignment"
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− | = | + | =Exercise To Revisit= |
− | + | In this studio we will complete the <code>EmptyImmutableList</code> and <code>NonEmptyImmutableList</code> implementations from the [[ImmutableList_Assignment|ImmutableList exercise]]. | |
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− | == | + | ==ImmutableList== |
− | + | The [https://www.cse.wustl.edu/~cosgroved/courses/cse425s/spring20/apidocs/immutable/list/core/ImmutableList.html ImmutableList] interface extends [https://docs.oracle.com/javase/8/docs/api/java/lang/Iterable.html Iterable] which has one method: [https://docs.oracle.com/javase/8/docs/api/java/lang/Iterable.html#iterator-- iterator()]. | |
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− | + | <nowiki>public interface ImmutableList<E> extends Iterable<E> { | |
− | + | E head(); | |
− | + | ImmutableList<E> tail(); | |
− | + | boolean isEmpty(); | |
+ | }</nowiki> | ||
− | + | ==Iterable== | |
− | == | + | [https://docs.oracle.com/javase/8/docs/api/java/lang/Iterable.html interface java.lang.Iterable<T>] |
− | + | #[https://docs.oracle.com/javase/8/docs/api/java/lang/Iterable.html#iterator-- Iterator<T> iterator()] | |
− | + | ==Iterator== | |
+ | [https://docs.oracle.com/javase/8/docs/api/java/util/Iterator.html interface java.util.Iterator<T>] | ||
+ | #[https://docs.oracle.com/javase/8/docs/api/java/util/Iterator.html#hasNext-- boolean hasNext()] | ||
+ | #[https://docs.oracle.com/javase/8/docs/api/java/util/Iterator.html#next-- T next()] | ||
− | + | =Examples= | |
+ | ==Using Iterable== | ||
+ | <youtube>A-rTJTHq5B4</youtube> | ||
+ | ==Implementing Iterable: DOM NodeList== | ||
+ | <youtube>4ycpqdJ4yb4</youtube> | ||
− | = | + | =Example= |
− | + | {{Example|IterableImmutableListExample|immutable.list.example}} | |
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− | {{ | ||
The code: | The code: | ||
<nowiki>ImmutableList<Integer> numbers = Lists.brackets(4, 66, 99); | <nowiki>ImmutableList<Integer> numbers = Lists.brackets(4, 66, 99); | ||
− | for ( | + | for (Integer i : numbers) { |
System.out.println(i); | System.out.println(i); | ||
}</nowiki> | }</nowiki> | ||
Line 55: | Line 39: | ||
66 | 66 | ||
99</nowiki> | 99</nowiki> | ||
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+ | =Diagrams= | ||
+ | ==ImmutableList== | ||
+ | <nowiki>ImList<Char> letters = Lists.brackets('A', 'B', 'C'); </nowiki> | ||
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+ | [[File:ImmutableList_letters.svg|600px]] | ||
+ | |||
+ | ==Initial Iterator State== | ||
+ | |||
+ | <nowiki>ImList<Char> letters = Lists.brackets('A', 'B', 'C'); | ||
+ | Iterator<Char> iter = letters.iterator(); </nowiki> | ||
+ | |||
+ | [[File:ImmutableList_iterator.svg|600px]] | ||
+ | |||
+ | ==Iterator State after next()== | ||
+ | |||
+ | <nowiki>ImList<Char> letters = Lists.brackets('A', 'B', 'C'); | ||
+ | Iterator<Char> iter = letters.iterator(); | ||
+ | if(iter.hasNext()) { | ||
+ | char a = iter.next(); | ||
+ | } </nowiki> | ||
+ | |||
+ | [[File:ImmutableList_iterator_next.svg|600px]] | ||
+ | |||
+ | ==Iterator State after next() next()== | ||
+ | <nowiki>ImList<Char> letters = Lists.brackets('A', 'B', 'C'); | ||
+ | Iterator<Char> iter = letters.iterator(); | ||
+ | if(iter.hasNext()) { | ||
+ | char a = iter.next(); | ||
+ | if(iter.hasNext()) { | ||
+ | char b = iter.next(); | ||
+ | } | ||
+ | } </nowiki> | ||
+ | |||
+ | [[File:ImmutableList_iterator_next_next.svg|600px]] | ||
+ | ==Iterator State after next() next() next()== | ||
+ | <nowiki>ImList<Char> letters = Lists.brackets('A', 'B', 'C'); | ||
+ | Iterator<Char> iter = letters.iterator(); | ||
+ | if(iter.hasNext()) { | ||
+ | char a = iter.next(); | ||
+ | if(iter.hasNext()) { | ||
+ | char b = iter.next(); | ||
+ | if(iter.hasNext()) { | ||
+ | char c = iter.next(); | ||
+ | } | ||
+ | } | ||
+ | } </nowiki> | ||
+ | |||
+ | [[File:ImmutableList_iterator_next_next_next.svg|600px]] | ||
+ | |||
+ | =Code To Implement= | ||
+ | ==enum EmptyImmutableList== | ||
+ | {{JavaToImplement|EmptyImmutableList|iterator|immutable.list.assignment}} | ||
+ | ===iterator()=== | ||
+ | return an [https://docs.oracle.com/javase/8/docs/api/java/util/Iterator.html Iterator] for the EmptyImmutableList. | ||
+ | |||
+ | Question to ask yourself: Does an iterator for an EmptyImmutableList ever have a next? | ||
+ | |||
+ | ==class NonEmptyImmutableList== | ||
+ | {{JavaToImplement|NonEmptyImmutableList|iterator|immutable.list.assignment}} | ||
+ | ===iterator()=== | ||
+ | return an [https://docs.oracle.com/javase/8/docs/api/java/util/Iterator.html Iterator] for this instance of NonEmptyImmutableList. | ||
+ | |||
+ | Note: If you are within an anonymous inner class, the way to get the outer class's this instance is to qualify it with the out class identifier. For example: | ||
+ | |||
+ | <nowiki>NonEmptyImmutableList.this</nowiki> | ||
=Test= | =Test= | ||
− | {{TestSuite| | + | {{TestSuite|IterableAssignmentTestSuite|immutable.list.util.exercise}} |
+ | |||
+ | :{{TestSuite|ImmutableListIteratorMethodTestSuite|immutable.list.util.exercise}} |
Latest revision as of 19:05, 24 April 2022
Exercise To Revisit
In this studio we will complete the EmptyImmutableList
and NonEmptyImmutableList
implementations from the ImmutableList exercise.
ImmutableList
The ImmutableList interface extends Iterable which has one method: iterator().
public interface ImmutableList<E> extends Iterable<E> { E head(); ImmutableList<E> tail(); boolean isEmpty(); }
Iterable
interface java.lang.Iterable<T>
Iterator
interface java.util.Iterator<T>
Examples
Using Iterable
Implementing Iterable: DOM NodeList
Example
class: | IterableImmutableListExample.java | |
package: | immutable.list.example | |
source folder: | src/main/java |
The code:
ImmutableList<Integer> numbers = Lists.brackets(4, 66, 99); for (Integer i : numbers) { System.out.println(i); }
produces:
4 66 99
Diagrams
ImmutableList
ImList<Char> letters = Lists.brackets('A', 'B', 'C');
Initial Iterator State
ImList<Char> letters = Lists.brackets('A', 'B', 'C'); Iterator<Char> iter = letters.iterator();
Iterator State after next()
ImList<Char> letters = Lists.brackets('A', 'B', 'C'); Iterator<Char> iter = letters.iterator(); if(iter.hasNext()) { char a = iter.next(); }
Iterator State after next() next()
ImList<Char> letters = Lists.brackets('A', 'B', 'C'); Iterator<Char> iter = letters.iterator(); if(iter.hasNext()) { char a = iter.next(); if(iter.hasNext()) { char b = iter.next(); } }
Iterator State after next() next() next()
ImList<Char> letters = Lists.brackets('A', 'B', 'C'); Iterator<Char> iter = letters.iterator(); if(iter.hasNext()) { char a = iter.next(); if(iter.hasNext()) { char b = iter.next(); if(iter.hasNext()) { char c = iter.next(); } } }
Code To Implement
enum EmptyImmutableList
class: | EmptyImmutableList.java | |
methods: | iterator | |
package: | immutable.list.assignment | |
source folder: | src/main/java |
iterator()
return an Iterator for the EmptyImmutableList.
Question to ask yourself: Does an iterator for an EmptyImmutableList ever have a next?
class NonEmptyImmutableList
class: | NonEmptyImmutableList.java | |
methods: | iterator | |
package: | immutable.list.assignment | |
source folder: | src/main/java |
iterator()
return an Iterator for this instance of NonEmptyImmutableList.
Note: If you are within an anonymous inner class, the way to get the outer class's this instance is to qualify it with the out class identifier. For example:
NonEmptyImmutableList.this
Test
class: | IterableAssignmentTestSuite.java | |
package: | immutable.list.util.exercise | |
source folder: | src/test/java |