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16public
17class Stack2 extends AbstractStack {
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23 private
24 java.util.Stack s;
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30 public
31 Stack2() {
32 s = new java.util.Stack();
33 }
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41 public
42 boolean isEmpty() {
43 return
44 s.empty();
45 }
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49 public
50 Object top()
51 {
52 assert preTop() : "Stack2.top: empty stack";
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54 return
55 s.peek();
56 }
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60 public
61 void push(Object o) {
62 s.push(o);
63 }
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67 public
68 void pop()
69 {
70 assert prePop() : "Stack2.pop: empty stack";
71 s.pop();
72 }
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74
75
76}
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78
