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public class Queue<E> {
 private int size;
 private Entry<E> firstEntry;
 private Entry<E> lastEntry; 
public Queue() {
 this.firstEntry = null;
 this.lastEntry = null;
}
public int size() { 
return this.size;
} 
}
public class Entry<E> {
 private E element; 
private Entry<E> next;
public Entry(E o, Entry<E> next) {
 this.element = o;
 this.next = next;
}
public E getElement() { 
return this.element;
}
public void setElement(E element) { 
this.element = element;
}
public Entry<E> getNext() {
 return this.next;
}
public void setNext(Entry<E> next) {
 this.next = next;
}
}

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public E get() {
Entry<E> currentEntry = this.firstEntry.getElement(); // hierweis unten 
if(currentEntry == null) {
throw new NullPointerException("empty queue");
} 
this.firstEntry = currentEntry.getNext();
 if(this.size == 1) {
this.lastEntry = null;
}
 this.size--;
return currentEntry.getElement(); 
}

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public boolean contains(E element) {
int i=0;
while(i<this.size) {
if(this.head.getElement().equals(element)) {
return true;
}this.head = this.head.getNext();
} 
return false;
 }

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public boolean contains(E element) {
 Entry<E> currentEntry = this.firstEntry;
while(currentEntry != null) {
if(currentEntry.getElement().equals(element)) {
return true;
}
 currentEntry = currentEntry.getNext();
}
 return false; }

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public boolean contains(E element) {
int i=0;
Entry<E> currentEntry = this.firstEntry;
while(i<this.size) {
if(currentEntry.getElement().equals(element)) {
return true;
}
currentEntry = currentEntry.getNext();
i++;
} 
return false;
 }

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public void put(E element) {
Entry<E> entry = new Entry<E>(element, null) ;
if(this.size == 0) {
this.firstEntry = entry;
} else {
Entry<E> currentEntry = this.lastEntry;
 currentEntry.setNext(entry); //[B] was wenn th.lastEntry null ist?[/B]
} 
this.lastEntry = entry;
 this.size++; 
}