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uebung09 small adjustments

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This commit is contained in:
Johannes Schmelz 2025-06-12 12:10:00 +02:00
parent 57aae3eda6
commit b2eb22a6cc
7 changed files with 300 additions and 119 deletions
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5
uebung09/src/chess/Board.java
View File

@ -1,10 +1,9 @@
package chess;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import iterator.Array2dIterator;
import iterator.SkipNullIterator;
public class Board implements Iterable<Piece> {
private final Piece[][] field = new Piece[8][8];
@ -66,6 +65,6 @@ public class Board implements Iterable<Piece> {
@Override
public Iterator<Piece> iterator() {
return new Array2dIterator<>(field);
return new SkipNullIterator<>(new Array2dIterator<>(field));
}
}

112
uebung09/src/collection/BigSet.java
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@ -1,21 +1,64 @@
package collection;
import java.util.Iterator;
import java.util.Objects;
class BigSet<E> implements Set<E> {
private final E first;
private final Set<E> rest;
private final int size;
private E first;
private Set<E> rest;
BigSet(E first, Set<E> rest) {
this.first = Objects.requireNonNull(first);
this.rest = Objects.requireNonNull(rest);
size = 1 + rest.size();
}
public BigSet(E first, Set<E> rest) {
this.first = first;
this.rest = rest;
@Override
public int size() {
return size;
}
@Override
public boolean isEmpty() {
return false;
}
@Override
public boolean contains(Object el) {
return first.equals(el) || rest.contains(el);
}
@Override
public boolean subsetOf(Set<?> other) {
return other.contains(first) && rest.subsetOf(other);
}
@Override
public Set<E> union(Set<E> other) {
return rest.union(other).add(first);
}
@Override
public Set<E> add(E element) {
if (contains(element))
return this;
return new BigSet<>(element, this);
}
@Override
public Set<E> intersection(Set<E> other) {
final Set<E> set = rest.intersection(other);
if (!other.contains(first))
return set;
else if (set.isEmpty())
return SetFactory.create(first);
return new BigSet<>(first, set);
}
@Override
public Iterator<E> iterator() {
return new Iterator<E>() {
return new Iterator<>() {
private int cnt;
private Iterator<E> restIt;
@ -33,48 +76,31 @@ class BigSet<E> implements Set<E> {
return restIt.next();
}
};
}
@Override
public int size() {
return rest.size() + 1;
public String toString() {
final StringBuilder b = new StringBuilder("{");
final Iterator<E> it = iterator();
while (it.hasNext()) {
b.append(it.next());
if (it.hasNext()) b.append(", ");
}
b.append('}');
return b.toString();
}
@Override
public boolean isEmpty() {
public int hashCode() {
return 31 * rest.hashCode() + first.hashCode();
}
@Override
public boolean equals(Object obj) {
if (obj instanceof Set<?>) {
final Set<?> other = (Set<?>) obj;
return this.size() == other.size() && this.subsetOf(other);
}
return false;
}
@Override
public boolean contains(Object el) {
return first.equals(el) || rest.contains(el);
}
@Override
public Set<E> union(Set<E> other) {
return rest.union(other).add(first);
}
@Override
public Set<E> add(E element) {
if (contains(element)) return this;
return new BigSet<E>(element, this);
}
@Override
public Set<E> intersection(Set<E> other) {
final Set<E> set = rest.intersection(other);
if (!other.contains(first))
return set;
else if (set.isEmpty())
return SetFactory.create(first);
return new BigSet<>(first, set);
}
@Override
public boolean subsetOf(Set<?> other) {
return other.contains(first) && rest.subsetOf(other);
}
}

63
uebung09/src/collection/EmptySet.java
View File

@ -5,23 +5,6 @@ import java.util.NoSuchElementException;
class EmptySet<E> implements Set<E> {
@Override
public Iterator<E> iterator() {
return new Iterator<E>() {
@Override
public boolean hasNext() {
return false;
}
@Override
public E next() {
throw new NoSuchElementException();
}
};
}
@Override
public int size() {
return 0;
@ -38,24 +21,56 @@ class EmptySet<E> implements Set<E> {
}
@Override
public Set union(Set other) {
public boolean subsetOf(Set<?> other) {
return true;
}
@Override
public Set<E> union(Set<E> other) {
return other;
}
@Override
public Set add(Object element) {
public Set<E> add(E element) {
return SetFactory.create(element);
}
@Override
public Set intersection(Set other) {
return new EmptySet();
//return this;
public Set<E> intersection(Set<E> other) {
return this;
}
@Override
public boolean subsetOf(Set other) {
return true;
public Iterator<E> iterator() {
return new Iterator<>() {
@Override
public boolean hasNext() {
return false;
}
@Override
public E next() {
throw new NoSuchElementException();
}
};
}
@Override
public String toString() {
return "{}";
}
@Override
public int hashCode() {
return 31;
}
@Override
public boolean equals(Object obj) {
if (obj instanceof Set<?>) {
@SuppressWarnings("unchecked") final Set<E> other = (Set<E>) obj;
return other.isEmpty();
}
return false;
}
}

29
uebung09/src/collection/SetDemo.java Normal file
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@ -0,0 +1,29 @@
package collection;
public class SetDemo {
public static void main(String[] args) {
final Set<String> set1 = SetFactory.create();
System.out.println("set1 = " + set1);
final Set<String> set2 = set1.add("foo");
System.out.println("set2 = " + set2);
final Set<String> set3 = set2.add("foo");
System.out.println("set3 = " + set3);
final Set<String> set4 = set3.add("bar");
System.out.println("set4 = " + set4);
final Set<String> set5 = SetFactory.create("foo", "baz", "foo");
System.out.println("set5 = " + set5);
final Set<String> set6 = set4.union(set5);
System.out.println("set6 = " + set6);
final Set<String> set7 = set4.intersection(set5);
System.out.println("set7 = " + set7);
final Set<String> set8 = set5.intersection(set4);
System.out.println("set8 = " + set8);
}
}

7
uebung09/src/collection/SetFactory.java
View File

@ -2,6 +2,9 @@ package collection;
public class SetFactory {
// Notwendig um einen korrekten Vergleich von EmptySet zu ermöglichen
private static final EmptySet<Object> EMPTY_SET = new EmptySet<>();
private SetFactory() { /* don't instantiate */ }
/**
@ -11,7 +14,7 @@ public class SetFactory {
* @return the empty set.
*/
static <T> Set<T> create() {
return new EmptySet<T>();
return (Set<T>) EMPTY_SET;
}
/**
@ -22,7 +25,7 @@ public class SetFactory {
* @return the singleton set containing the specified element.
*/
static <T> Set<T> create(T element) {
return new SingeltonSet<T>(element);
return new SingeltonSet<>(element);
}
/**

92
uebung09/src/collection/SingeltonSet.java
View File

@ -2,37 +2,13 @@ package collection;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Objects;
class SingeltonSet<E> implements Set<E> {
private final E element;
private final E elem;
public SingeltonSet(E elem) {
this.elem = elem;
}
@Override
public Iterator iterator() {
return new Iterator<E>() {
boolean returned = true;
@Override
public boolean hasNext() {
return returned;
}
@Override
public E next() {
if(!hasNext()) {
throw new NoSuchElementException();
}
returned = false;
return elem;
}
};
SingeltonSet(E element) {
this.element = Objects.requireNonNull(element);
}
@Override
@ -47,31 +23,67 @@ class SingeltonSet<E> implements Set<E> {
@Override
public boolean contains(Object el) {
return elem.equals(el);
return element.equals(el);
}
@Override
public Set union(Set other) {
return other.add(elem);
public boolean subsetOf(Set<?> other) {
return other.contains(element);
}
@Override
public Set add(Object element) {
if (elem.equals(element)) {
public Set<E> union(Set<E> other) {
return other.add(element);
}
@Override
public Set<E> add(E element) {
if (this.element.equals(element))
return this;
}
return new BigSet(element, this);
return new BigSet<>(element, this);
}
@Override
public Set intersection(Set other) {
return other.contains(elem) ? this : SetFactory.create();
public Set<E> intersection(Set<E> other) {
return other.contains(element) ? this : SetFactory.create();
}
@Override
public boolean subsetOf(Set other) {
return other.contains(elem);
public Iterator<E> iterator() {
return new Iterator<>() {
boolean ready = true;
@Override
public boolean hasNext() {
return ready;
}
@Override
public E next() {
if (!ready)
throw new NoSuchElementException();
ready = false;
return element;
}
};
}
@Override
public String toString() {
return "{" + element + "}";
}
@Override
public int hashCode() {
return 47 * element.hashCode();
}
@Override
public boolean equals(Object obj) {
if (obj instanceof Set<?>) {
final Set<?> other = (Set<?>) obj;
return other.size() == 1 && other.contains(element);
}
return false;
}
}

97
uebung09/src/iterator/IteratorDemo.java Normal file
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@ -0,0 +1,97 @@
package iterator;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
public class IteratorDemo {
private static void demoArray2dIterator() {
System.out.println("Array2dIterator {{}, {\"foo\", \"bar\"}, {\"baz\"}, {}}");
final String[][] array = {{}, {"foo", "bar"}, {"baz"}, {}};
final Iterator<String> it = new Array2dIterator<>(array);
while (it.hasNext())
System.out.println(it.next());
}
private static void demoArray2dIteratorOnlyEmpty() {
System.out.println("Array2dIterator {{}, {}, {}}");
final String[][] array = {{}, {}, {}};
final Iterator<String> it = new Array2dIterator<>(array);
while (it.hasNext())
System.out.println(it.next());
}
private static void demoArray2dIteratorEmpty() {
System.out.println("Array2dIterator {}");
final String[][] array = {};
final Iterator<String> it = new Array2dIterator<>(array);
while (it.hasNext())
System.out.println(it.next());
}
private static void demoSkipNullIterator() {
System.out.println("SkipNullIterator [\"a\", \"b\", null, \"c\"]");
final Iterator<String> oriIt = Arrays.asList("a", "b", null, "c").iterator();
final Iterator<String> it = new SkipNullIterator<>(oriIt);
while (it.hasNext())
System.out.println(it.next());
}
private static void demoSkipNullIteratorSingleton() {
System.out.println("SkipNullIterator [\"foo\"]");
final Iterator<String> oriIt = List.of("foo").iterator();
final Iterator<String> it = new SkipNullIterator<>(oriIt);
while (it.hasNext())
System.out.println(it.next());
}
private static void demoSkipNullIteratorInfinity() {
System.out.println("SkipNullIterator [\"infinity\", \"infinity\", ...]");
final Iterator<String> oriIt = new Iterator<>() {
@Override
public boolean hasNext() {
return true;
}
@Override
public String next() {
return "infinity";
}
};
final Iterator<String> it = new SkipNullIterator<>(oriIt);
for (int i = 0; i < 10; i++)
System.out.println(i + ": " + it.next());
}
private static void demoPathological() {
System.out.println("SkipNullIterator [null, ..., null, \"infinity\", \"infinity\", ...]");
final Iterator<String> oriIt = new Iterator<>() {
private int ctr;
@Override
public boolean hasNext() {
return true;
}
@Override
public String next() {
return ctr++ > 100000 ? "infinity" : null;
}
};
final SkipNullIterator<String> it = new SkipNullIterator<>(oriIt);
for (int i = 0; i < 10; i++)
System.out.println(i + ": " + it.next());
}
public static void main(String[] args) {
demoArray2dIterator();
demoArray2dIteratorEmpty();
demoArray2dIteratorOnlyEmpty();
demoSkipNullIterator();
demoSkipNullIteratorSingleton();
demoSkipNullIteratorInfinity();
demoPathological();
}
}