ka obs stimmt. nur damit mal was da draussen rumschwirrt. wie wärs wenn mehr leute wieder teilen würden?
mfg, mike
//wir haben es so gemacht wie auf folie28,
//da es in der vorlesung mehrere möglichkeiten
//gab, diese aufgabe zu lösen
/* A stack with a fixed maximum capacity */
//klasseninvariante: content!=null
public class Stack<X> {
int topIx; // index in content of the top element
final X[] content; // array that stores the elements of the stack
@post {this.content.length>0}
public Stack(int capacity) {
this.content = (X[]) new Object[capacity];
this.topIx = -1;
}
@pre {capacity>0}
@post {content.length=oldcontent.length+1}
public X top() {
return this.content[this.topIx];
}
@pre {content!=null}
@post {topIx=oldtopIx-1 && content.length=oldcontent.length}
public X pop() {
X res = this.content[this.topIx];
this.topIx--;
return res;
}
@pre {content.length>0}
@post {content.length=oldcontent.length+1}
public void push(X x) {
this.topIx++;
this.content[this.topIx] = x;
}
@pre {content!=null}
@post {topIx=-1 && content!=null}
public boolean isEmpty() {
return this.topIx == -1;
}
@pre {content!=null}
@post {topIx=content.length-1 && content!=null}
public boolean isFull() {
return this.topIx == (this.content.length - 1);
}
@pre {content.length>0}
public static void main(String[] args) {
// some tests
Stack<String> stack = new Stack<String>(2);
System.out.println(stack.isEmpty());
System.out.println(stack.isFull());
stack.push("1");
stack.push("2");
System.out.println(stack.isEmpty());
System.out.println(stack.isFull());
System.out.println(stack.pop());
stack.push("3");
System.out.println(stack.pop());
System.out.println(stack.pop());
System.out.println(stack.isEmpty());
System.out.println(stack.isFull());
stack.push("4");
System.out.println(stack.pop());
}
}
a)
interface Map<K,V> {
@post {key!=null && key is element in Map}
boolean containsKey(K key);
@pre {key!=null}
@post {key!=null && (containsKey(key) OR return null)}
V get(K key);
@pre {key!=null}
@post {containsKey(key)}
void put(K key, V value);
@pre {key!=null}
}
