Khin Khin Zaw

A proposal of three extensions in blank element selection algorithm for Java programming learning assistant system

To assist Java programming educations, we have developed a Web-based Java Programming Learning Assistant System (JPLAS). JPLAS provides fill-in-blank problems to let students study Java grammar and basic programming skills by filling the blanked elements in a given Java code. To generate the feasible problems, we have proposed a blank element selection algorithm using the constraint graph to select as many blanks as possible such that they have grammatically correct and unique answers. In this paper, to further increase the number of blanks and control the difficulty of the generated problem, we extend this algorithm by 1) adding operators in conditional expressions for blank candidates, 2) improving the edge generation method in the constraint graph to increase the number of blanks, and 3) introducing two parameters to change the frequency of selecting blanks. To verify the effectiveness, we apply the extended algorithm to 55 Java codes for fundamental data structure or algorithms, and confirm that these extensions can increase the number of blanks and change the problem difficulty.

A fill-in-blank problem workbook for Java programming learning assistant system

Purpose To advance Java programming educations, the authors have developed a Java Programming Learning Assistant System (JPLAS) as a web application system. JPLAS provides fill-in-blank problems for novices to study the grammar and basic programming skills through code reading. Design/methodology/approach To select the blank elements with grammatically correct and unique answers from a given Java code, the authors have proposed the graph-based blank element selection algorithm. Then, the code for this problem should be highly readable to encourage novice students to study it. Because code readability can be improved by proper names for identifiers, the authors have also proposed the naming rule testing algorithm to identify codes with correct names. Findings In this paper, the authors present a fill-in-blank problem workbook by collecting suitable Java codes from textbooks and Web sites and applying these algorithms with several extensions. The workbook consists of 16 categories with a considerable number of problems that follow the conventional learning order of Java programming. Originality/value The proper set of ready-made fill-in-blank problems is effective in enhancing the usability of JPLAS both for teachers and students. For the preliminary evaluation, the authors assign a few problems to students. In coming semesters, the authors will use this workbook in the course to verify the adequacy of the proposal for novices.

A design-aware test code approach for code writing problem in Java programming learning assistant system

To advance Java programming educations, we have developed the Web-based Java Programming Learning Assistant System (JPLAS) that provides the code writing problem among the four type problems with different levels. This problem asks a student to write a Java source code for a given assignment, where the correctness is verified by running the test code on JUnit. Unfortunately, it is found that even after solving many simple problems, a lot of students cannot solve harder problems that require multiple classes/methods, where the proper code design is necessary. In this paper, we propose a design-aware test code approach for the code writing problem in JPLAS. The designaware test code is generated to test any important method in the model code that has the advisable design for the problem. By writing a code that can pass this test code, a student is expected to implement the code with the proper classes/methods in the model code. For evaluations, we asked seven students to write the source code for the breadthfirst-search (BFS) algorithm of a graph without/with using the design-aware test code. Then, only one student could complete it without it, whereas all of them could do so with it. Besides, the code quality metrics measured by Metrics plugin for Eclipse showed that the design-aware test code is very helpful for students to write highly qualitative codes. These results were also confirmed in other graph algorithms.

A Minimax Approach for Access-Point Setup Optimization Using Throughput Measurements in IEEE802.11n Wireless Networks

Recently, an IEEE802.11n access point (AP) has become common in the wireless local-area network (WLAN) due to the high-speed data transmission using the multiple input multiple output (MIMO) technology. However, the signal propagation from the 802.11n AP may not be uniform in the circumferential direction because of multiple antennas in MIMO, in addition to the height direction. As a result, the data transmission speed between the AP and a host can be significantly affected by their relative setup conditions. In this paper, we propose a minimax approach for optimizing the 802.11n AP setup condition in terms of the height and the angles in an indoor environment using throughput measurements. First, we detect a bottleneck host that receives the weakest signal from the AP in the field using the throughput estimation model. Then, we optimize the AP setup by changing the height and directions while measuring throughputs. For evaluations, we confirm the accuracy of the model using measurement results and the throughput improvements at most hosts including the bottleneck one in the field by our approach.

A Concept of Value Trace Problem for Java Code Reading Education

To assist Java programming educations, we have developed a Web-based Java Programming Learning Assistant System (JPLAS). JPLAS provides the fill-in-blank problem to help novice students studying Java programming at home, where some elements in a high-quality code including reserved words, identifiers, and control symbols are blanked to be filled by students. Unfortunately, this problem may be solved without reading out the algorithm in the code if students are familiar with Java grammar to some extent. In this paper, to further cultivate the code reading capability of students, we propose a concept of the value trace problem to ask the actual values of important variables in a code implementing some fundamental data structure or algorithm. A value trace problem can be generated by: 1) selecting a high-quality class code for the algorithm to be studied, 2) making the main class to instantiate the class in 1) if it does not contain the main method, 3) adding the functions to output variable values in questions into a text file, 4) preparing the input file to the code in 3) if necessary, 5)running this code to obtain the set of variable values in the text file, 6) blanking some values from the text file to be filled by students, and 7) uploading the final code, the blanked text file, and the correct answer file into the JPLAS server, and adding the brief description on the algorithm for a new assignment. To verify the feasibility of this concept, we manually generated five problems and asked four students with high Java programming skills in our group to solve them. Then, we analyzed the difficulty of the value trace problem for Quick Sort.

An Improved Informative Test Code Approach for Code Writing Problem in Java Programming Learning Assistant System

The Java Programming Learning Assistant System (JPLAS) has been studied to enhance Java programming educations by offering advanced self-learning environments. As one problem type in JPLAS, the code writing problem asks a student to write a source code to satisfy the specifications described in a test code that verifies the correctness of the code on JUnit. Previously, we proposed an informative test code approach to help a novice student to complete a complex source code using concepts in the object-oriented programming. It describes the necessary information to implement the code, such as names, access modifiers, and data types of classes, methods, and variables, in addition to behaviors. Unfortunately, it has drawbacks in handling input/output files for an assignment. In this paper, we propose an improved informative test code approach by adopting the standard input/output to solve them. For evaluations, we generated improved informative test codes for five graph algorithms and requested three students in our group to write the source codes, where all of them completed the source codes with high software metrics.

A parameter optimization tool and its application to throughput estimation model for wireless LAN

Most of algorithms or logics to solve mathematical problems adopt multiple parameters such as coefficients and thresholds whose values should be carefully selected to enhance the performance. Conventionally, their developers or users tune them by trial and error, where they repeat to apply algorithms or logics with proper parameter values to available input data sets and modify them based on the results. As a result, this tuning process may consume a great deal of energy and not always provide the optimal ones. In this paper, we present a versatile parameter optimization tool to explore optimal values of parameters for various algorithms/logics. We show the effectiveness through applications for the throughput estimation model for wireless local-area networks, with the extension of the model.

A Workbook Design for Fill-in-Blank Problems in Java Programming Learning Assistant System

To advance Java programming educations, we have developed a Java Programming Learning Assistant System (JPLAS) as a Web application system. JPLAS provides fill-in-blank problems for novice students to study the grammar and basic programming skills through code reading. To select the blank elements with grammatically correct and unique answers from a given code, we have proposed the graph-based blank element selection algorithm. Then, we generated and assigned fill-in-blank problems to students in Java programming course for two years. Unfortunately, the teacher selected original Java codes rather arbitrarily, which may degrade educational effects. Besides, this algorithm has been continuously extended to enhance the variations of generated problems. In this paper, we present a workbook design for fill-in-blank problems in JPLAS by collecting suitable Java codes from textbooks and Web sites, and applying the extended algorithm, so that they can be instantly and properly assigned to students. This workbook design consists of 15 categories with a considerable number of problems that follow the conventional learning order of Java programming. For the preliminary evaluation, we assign some problems to novice students. In the coming semester, we will use this workbook in the course to verify the adequacy of our proposal for novice students.