概述：
面向对象第三单元的任务是根据JML规格，继承相应的接口，实现相应的类。其中涉及一系列的算法以及数据结构的选择问题，高效的算法和合适的数据结构能够减少CPU时间、运行时间和运行内存，使得程序得到优化。
一、梳理JML语言的理论基础、应用工具链情况
1、理论基础
Java建模语言是用于对Java程序进行规格化设计的一种表示语言。在Java代码中增加了一些符号，这些符号用来标识一个方法是干什么的，却并不关心它的实现。
JML规格大致包含以下内容：
public model instance JMLObjectBag elementsInQueue;（模型域）
public normal_behavior（方法正常功能）
public exceptional_behavior（方法异常功能）
requires（前置条件）
ensures（后置条件）
assignable（副作用范围限定）
JML表达式（\result \old() \forall \exists \nothing\everything <=!=> <==> ==>等）
invariant（不变式）
constraint（状态变化约束）
2、应用工具链
openjml测试JML语言的正确性
Junit4生成模板，构造测试样例，单独测试每个函数是否符合JML
JMLUnitNG自动生成测试样例
二、部署SMTSolver，至少选择3个主要方法来尝试进行验证，报告结果
环境为IDEA+openjml插件+openjml，对第9次作业的MyPathContainer.java进行测试，第一次运行结果如下：
| Start OpenJML/ESC with file MyPathContainer.java
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:66: 错误: A \old token with no label may not be present in a requires clause
@ requires path != null && path.isValid() && \old(containsPath(path));
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:82: 错误: A \old token with no label may not be present in a requires clause
@ requires \old(containsPathId(pathId));
^
2 个错误 |
报告了两个规格的错误，修改之后再次运行，报了更多的错误......如下：
| Start OpenJML/ESC with file MyPathContainer.java
错误: A catastrophic JML internal error occurred. Please report the bug with as much information as you can.
Reason: Mismatch in number of arguments in accumulateTypeInstantiations
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:54: 警告: The prover cannot establish an assertion (ArithmeticOperationRange) in method addPath: overflow in int sum
id++;
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:57: 警告: The prover cannot establish an assertion (ArithmeticOperationRange) in method addPath: overflow in int sum
sizeall++;
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:49: 警告: The prover cannot establish an assertion (ExceptionalPostcondition: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:58: 注: ) in method addPath
if (path == null || !path.isValid()) {
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:58: 警告: Associated declaration: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:49: 注:
@ normal_behavior
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:52: 警告: The prover cannot establish an assertion (Postcondition: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:49: 注: ) in method addPath
return pathMap.get(path);
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:49: 警告: Associated declaration: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:52: 注:
@ ensures (pidList.length == pList.length);
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:52: 警告: The prover cannot establish an assertion (Postcondition: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:50: 注: ) in method addPath
return pathMap.get(path);
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:50: 警告: Associated declaration: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:52: 注:
@ ensures (\exists int i; 0 <= i && i < pList.length; pList[i] == path &&
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:52: 警告: The prover cannot establish an assertion (Postcondition: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:55: 注: ) in method addPath
return pathMap.get(path);
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:55: 警告: Associated declaration: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:52: 注:
@ ensures (\forall int i; 0 <= i && i < \old(pList.length);
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:49: 警告: The prover cannot establish an assertion (ExceptionalPostcondition: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:46: 注: ) in method addPath
if (path == null || !path.isValid()) {
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:46: 警告: Associated declaration: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:49: 注:
/*@ normal_behavior
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:25: 警告: The prover cannot establish an assertion (Postcondition: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:12: 注: ) in method containsPath
return pathMap.containsKey(path);
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:12: 警告: Associated declaration: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:25: 注:
@ ensures \result == (\exists int i; 0 <= i && i < pList.length;
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:29: 警告: The prover cannot establish an assertion (Postcondition: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:17: 注: ) in method containsPathId
return idMap.containsKey(pathId);
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:17: 警告: Associated declaration: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:29: 注:
/*@ ensures \result == (\exists int i; 0 <= i && i < pidList.length;
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:98: 警告: The prover cannot establish an assertion (Postcondition: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:94: 注: ) in method getDistinctNodeCount
return sizedis;
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:94: 警告: Associated declaration: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:98: 注:
/*@ ensures (\exists int[] arr; (\forall int i, j; 0 <= i && i < j && j < arr.length; arr[i] != arr[j]);
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:33: 警告: The prover cannot establish an assertion (ExceptionalPostcondition: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:22: 注: ) in method getPathById
if (!containsPathId(pathId)) {
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:22: 警告: Associated declaration: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:33: 注:
/*@ public normal_behavior
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:33: 警告: The prover cannot establish an assertion (ExceptionList: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:30: 注: ) in method getPathById
if (!containsPathId(pathId)) {
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:30: 警告: Associated declaration: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:33: 注:
@ signals_only PathIdNotFoundException;
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:36: 警告: The prover cannot establish an assertion (Postcondition: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:25: 注: ) in method getPathById
return idMap.get(pathId);
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:25: 警告: Associated declaration: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:36: 注:
@ ensures (pidList.length == pList.length) && (\exists int i; 0 <= i && i < pList.length; pidList[i] == pathId && \result == pList[i]);
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:42: 警告: The prover cannot establish an assertion (ExceptionalPostcondition: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:40: 注: ) in method getPathId
throw new PathNotFoundException(path);
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:40: 警告: Associated declaration: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:42: 注:
@ signals (PathNotFoundException e) path == null;
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:44: 警告: The prover cannot establish an assertion (Postcondition: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:37: 注: ) in method getPathId
return pathMap.get(path);
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:37: 警告: Associated declaration: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:44: 注:
@ ensures (pidList.length == pList.length) && (\exists int i; 0 <= i && i < pList.length; pList[i].equals(path) && pidList[i] == \result);
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:44: 警告: The prover cannot establish an assertion (Postcondition: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:39: 注: ) in method getPathId
return pathMap.get(path);
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:39: 警告: Associated declaration: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:44: 注:
@ public exceptional_behavior
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:41: 警告: The prover cannot establish an assertion (ExceptionalPostcondition: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:34: 注: ) in method getPathId
if (path == null || !path.isValid() || !containsPath(path)) {
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:34: 警告: Associated declaration: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:41: 注:
/*@ public normal_behavior
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:65: 警告: The prover cannot establish an assertion (ExceptionalPostcondition: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:75: 注: ) in method removePath
throw new PathNotFoundException(path);
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:75: 警告: Associated declaration: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:65: 注:
@ signals (PathNotFoundException e) path == null;
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:64: 警告: The prover cannot establish an assertion (ExceptionalPostcondition: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:65: 注: ) in method removePath
if (path == null || !path.isValid() || !containsPath(path)) {
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:65: 警告: Associated declaration: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:64: 注:
/*@ public normal_behavior
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:77: 警告: The prover cannot establish an assertion (ExceptionalPostcondition: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:81: 注: ) in method removePathById
if (!containsPathId(pathId)) {
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:81: 警告: Associated declaration: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:77: 注:
/*@ public normal_behavior
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:78: 警告: The prover cannot establish an assertion (ExceptionalPostcondition: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:90: 注: ) in method removePathById
throw new PathIdNotFoundException(pathId);
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:90: 警告: Associated declaration: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:78: 注:
@ signals (PathIdNotFoundException e) !containsPathId(pathId);
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:21: 警告: The prover cannot establish an assertion (Postcondition: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:7: 注: ) in method size
return sizeall;
^
C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\PathContainer.java:7: 警告: Associated declaration: C:\Users\Administrator\Desktop\HW09\HW9\src\com\oocourse\specs1\models\MyPathContainer.java:21: 注:
//@ ensures \result == pList.length;
^
1 个错误
42 个警告 |
前两个错误是整数溢出。
三、部署JMLUnitNG/JMLUnit,针对Graph接口的实现自动生成测试用例，并针对规格对生成的测试用例和数据进行简要分析
对compare函数进行测试，函数内容如下图：
生成的测试文件如下图：
测试过程及运行结果如下图：
发现自动生成的测试样例是通过判断大数据和零来验证结果的。
四、按照作业梳理自己的架构设计，并特别分析迭代器中对架构的重构
1、第9次作业架构
MyPath.java中用ArrayList和HashSet双容器来存一条路径上的节点，根据下标查找用ArrayList，根据nodeid查找用HashSet。
MyPathContainer.java中用了两个HashMap分别将Path映射到Pathid和将Pathid映射到Path,增删Path时同时对两个容器操作。寻找不同节点个数时，将Path中所有的node都放到一个HashSet中，计算该HashSet的大小。
2、第10次作业架构
MyGraph.java中用HashMap<Edge, Integer>来保存每个边出现的次数，其中Edge是一个class，包含(int fromNode,int toNode)代表边上的两个端点。用floyd算法计算出每两个点之间的最短路径，用HashMap<Edge, Integer>存放结果，代表每两个点之间的最短路径，每次增删节点时重新计算一遍。
3、第11次作业架构
MyRailwaySystem.java中用HashMap将nodeid映射到[0,120)，之后根据四个不同的问题分别跑floyd算法。
最短路径问题，将有边的两个点之间初始化为边的长度，其余的点之间初始化为-1，跑floyd算法，将结果存放在二维数组中。
最小换乘问题，将每条路径上的每两个点之间初始化为1，其余的点之间初始化为-1，跑floyd算法，将结果存放在二维数组中。
最低票价问题，将每条路径上的每两点之间初始化为二者之间的最短路径+2，其余的点之间初始化为-1，跑floyd算法，将结果存放在二维数组中。
最小不满意度问题，将每条路径上的每两点之间初始化为二者之间的最小不满意度+32，其余的点之间初始化为-1，跑floyd算法，将结果存放在二维数组中。
连通块的个数用并查集来求。
每次增删path重新计算一遍。
五、按照作业分析代码实现的bug和修复情况
代码的正确性上来讲是没有bug的，但是对于第10次作业，强测中出现了大量的CPU超时。经过分析，超时的原因是，我的代码中实现了一个Edge类(其中包含(int fromNode,int toNode))，类中存了这条边的两个端点，程序中大量的new Edge导致了时间和空间的损失，特别是当nodeid特别大的时候，超时明显。
为了修复这个bug，我应该将nodeid映射到[0,200),并采用别的数据结构例如静态数组来存放边。
六、阐述对规格撰写和理解上的心得体会
规格的撰写是一个需要大量的思考的过程，应该将每种情况都考虑到，从而保证正确性。
而规格的解读加代码实现的过程，是一个思维转换的过程，因为规格中的数据结构并不一定是你代码实现的数据结构。规格中的数据结构是为了说明正确性方便，代码中的数据结构要考虑正确性+效率。