Here is a reference solution<\/p>\n\n\n\n
public class TeacherReferenceSolutions {\n\n\n \/* Method 1 for the Teacher (it's the answer) *\/\n public int[] teacherMethod(int[] originalArray){\/\/, int checkValue) {\n\n int n = originalArray.length;\n int m = n\/2;\n int i = 0;\n int j = m;\n int k = 0;\n\n int[] outputArray = new int[n];\n\n while(i < m){\n outputArray[k++] = originalArray[i++];\n outputArray[k++] = originalArray[j++];\n }\n\n \/\/ System.arraycopy(outputArray,0,originalArray,0,k);\n\n return outputArray;\n }\n }<\/code><\/pre>\n\n\n\nHere is the Java jUnit test.<\/p>\n\n\n\n
import org.junit.Assert;\nimport org.junit.Test;\n\nimport javax.swing.*;\nimport java.util.*;\nimport java.util.List;\n\n\npublic class TheTestClass {\n\n\n\n @Test\n \/\/ method\n public void testOne() {\n\n TeacherReferenceSolutions theReference = new TeacherReferenceSolutions();\n StudentSolution theStudentAttempt = new StudentSolution();\n int[] studentAnswer;\n int[] teacherAnswer;\n\n final int MIN_INPUT = -10; \/\/ Boundaries on inputs (max, min)\n final int MAX_INPUT = +20;\n final int TEST_TOTALNUMBER = 5; \/\/ Number of sub-tests run on student vs. teacher.<\/span>\n final int LENGTH_ROWVECTOR = 10; \/\/ number of entries in each row vector.<\/span>\n final int thresholdValue = new Random().nextInt(MAX_INPUT - MIN_INPUT) + MIN_INPUT; \/\/ this is the max value to be compared against.<\/span>\n int[] oneRowVector = new int[LENGTH_ROWVECTOR];\n ArrayList<int[]> allTestArrays = new ArrayList<>();\n\n \/\/ Populate an ArrayList of row vectors. Each row vector is a new test set.\n<\/span> for(int i = 0; i < TEST_TOTALNUMBER; i++){\n for(int j = 0; j < LENGTH_ROWVECTOR; j++){\n oneRowVector[j] = new Random().nextInt(MAX_INPUT - MIN_INPUT) + MIN_INPUT;\n }\n allTestArrays.add(oneRowVector); \/\/ add one row at a time.\n }\n\n \/\/ Make a copy of the test array and make it immutable. <\/span>(doesn't work in current version of JDK with VPL)<\/span>\n \/\/ https:\/\/docs.oracle.com\/en\/java\/javase\/11\/core\/creating-immutable-lists-sets-and-maps.html#GUID-DB0865D2-C052-40BC-A3DC-20FCB3088DC9\n \/\/ List<int[]> ALL_TEST_ARRAYS = List.copyOf(allTestArrays);<\/span>\n\n \/* -----------------------------------\n * First loop. Print to screen messages that students can more easily decode.\n * ----------------------------------- *\/<\/span>\n for (int testIteration = 0; testIteration < TEST_TOTALNUMBER; testIteration++) {\n\n \/\/ extract an integer array for testing (one per row). \n<\/span> int[] singleRowVectorInput = allTestArrays.get(testIteration);\n\n \/* Run the teacher solution once. Get the reference output. *\/\n<\/span> int[] clonedCopyInputForTeacher = singleRowVectorInput.clone();\n teacherAnswer = theReference.teacherMethod(clonedCopyInputForTeacher);\n System.out.println(\"Subtest \" + testIteration + \" : testing against inputs : \\t\\t\\t\"\n + Arrays.toString(singleRowVectorInput) );\n\n \/\/ Run the student's answer. Get the student's output. *\/\n<\/span> int[] clonedCopyInputForStudent = singleRowVectorInput.clone();\n studentAnswer = theStudentAttempt.studentMethod(clonedCopyInputForStudent);\n\n\n try {\n Assert.assertArrayEquals(teacherAnswer, studentAnswer);\n System.out.println(\"Sub-Test \" + testIteration + \" _passed_. Testing against inputs : \\t\" + Arrays.toString(singleRowVectorInput));\n System.out.println(\"Teacher solution: \" + Arrays.toString(teacherAnswer) +\n \" ... versus student solution: \" + Arrays.toString(studentAnswer));\n System.out.println(\"------------------------------------------------------\");\n System.out.println(\"\");\n\n } catch (AssertionError e) {\n System.out.println(\"\");\n System.out.println(\"****************************************************\");\n System.out.println(\"vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv\");\n System.out.println(\"\\n\\t\\t\\t Sub-Test \" + testIteration + \" + DID NOT PASS!! \\t\\t\\t\\t\");\n System.out.println(\"For inputs \\t\\t\\t\\t\\t\\t\\t\\t\\t\\t\" + Arrays.toString(singleRowVectorInput));\n System.out.println(\"Sub-Test \" + testIteration + \" FAILED. Testing against inputs : \\t\" + Arrays.toString(singleRowVectorInput));\n\n System.out.println(\"We have teacher solution \" + Arrays.toString(teacherAnswer) +\n \" & student output: \" + Arrays.toString(studentAnswer));\n System.out.println(e.getMessage());\n System.out.println(\"\");\n System.out.println(\"^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\");\n System.out.println(\"****************************************************\");\n System.out.println(\"\");\n }\n }\n\n\n \/* ---------------------------------------------\n * Second loop. Allows jUnit to register the error in VPL or in the IDE.\n * ---------------------------------------------- *\/<\/span>\n for (int testIteration = 0; testIteration < TEST_TOTALNUMBER; testIteration++) {\n\n \/\/ extract an integer array for testing (one per row). \n<\/span> int[] singleRowVectorInput = allTestArrays.get(testIteration);\n\n \/* Run the teacher solution once. Get the reference output. *\/\n<\/span> int[] clonedCopyInputForTeacher = singleRowVectorInput.clone();\n teacherAnswer = theReference.teacherMethod(clonedCopyInputForTeacher);\n System.out.println(\"Subtest \" + testIteration + \" : testing against inputs : \" + Arrays.toString(singleRowVectorInput) );\n \/\/ Run the student's answer. Get the student's output. *\/<\/span>\n int[] clonedCopyInputForStudent = singleRowVectorInput.clone();\n studentAnswer = theStudentAttempt.studentMethod(clonedCopyInputForStudent);\n\n \/\/ no try-catch here. This will register with the IDE or VPL\n<\/span> Assert.assertArrayEquals(teacherAnswer, studentAnswer);\n\n\n }\n\n } \/\/ end method<\/span>\n\n\n\n\n}<\/code><\/pre>\n\n\n\n![\"a](\"https:\/\/www.yorku.ca\/professor\/drsmith\/wp-content\/uploads\/sites\/444\/2021\/12\/noun-signature-1720818-2.png\")
<\/figure><\/div>\n\n\n\nJames Andrew Smith is a Professional Engineer and Associate Professor in the Electrical Engineering and Computer Science\u00a0Department<\/a>\u00a0of York University's\u00a0Lassonde School<\/a>, with degrees in Electrical and Mechanical Engineering\u00a0from the University of Alberta and McGill University.\u00a0\u00a0Previously a program director in biomedical engineering, his research background spans robotics, locomotion, human birth and\u00a0engineering\u00a0education. While on sabbatical in 2018-19 with his wife and kids he lived in Strasbourg, France and\u00a0he\u00a0taught at the\u00a0INSA Strasbourg<\/a>\u00a0and\u00a0Hochschule Karlsruhe<\/a>\u00a0and wrote about his\u00a0personal<\/a>\u00a0and\u00a0professional\u00a0<\/a>perspectives<\/a>.\u00a0\u00a0James is a proponent of using social media to advocate for justice, equity, diversity and inclusion as well as evidence-based applications of research\u00a0in the public sphere.\u00a0You can find him on\u00a0Twitter<\/a>. Originally from Qu\u00e9bec City, he now lives in Toronto, Canada.\u00a0\u00a0<\/p>\n\n\n\n
\n","protected":false},"excerpt":{"rendered":"On a recent final exam I had students create a method that could interleave two halves of an array. The original exercise came from a Schaum's Outline book. If you're not careful, by passing values by reference you can have the student's solution pollute the original input test value. To solve this in Java you […]<\/p>\n","protected":false},"author":762,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_kad_blocks_custom_css":"","_kad_blocks_head_custom_js":"","_kad_blocks_body_custom_js":"","_kad_blocks_footer_custom_js":"","footnotes":""},"categories":[50,294],"tags":[],"class_list":["post-3411","post","type-post","status-publish","format-standard","hentry","category-java","category-vpl"],"taxonomy_info":{"category":[{"value":50,"label":"java"},{"value":294,"label":"VPL"}]},"featured_image_src_large":false,"author_info":{"display_name":"drsmith","author_link":"https:\/\/www.yorku.ca\/professor\/drsmith\/author\/drsmith\/"},"comment_info":"","category_info":[{"term_id":50,"name":"java","slug":"java","term_group":0,"term_taxonomy_id":50,"taxonomy":"category","description":"","parent":0,"count":27,"filter":"raw","cat_ID":50,"category_count":27,"category_description":"","cat_name":"java","category_nicename":"java","category_parent":0},{"term_id":294,"name":"VPL","slug":"vpl","term_group":0,"term_taxonomy_id":294,"taxonomy":"category","description":"","parent":0,"count":25,"filter":"raw","cat_ID":294,"category_count":25,"category_description":"","cat_name":"VPL","category_nicename":"vpl","category_parent":0}],"tag_info":false,"_links":{"self":[{"href":"https:\/\/www.yorku.ca\/professor\/drsmith\/wp-json\/wp\/v2\/posts\/3411","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.yorku.ca\/professor\/drsmith\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.yorku.ca\/professor\/drsmith\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.yorku.ca\/professor\/drsmith\/wp-json\/wp\/v2\/users\/762"}],"replies":[{"embeddable":true,"href":"https:\/\/www.yorku.ca\/professor\/drsmith\/wp-json\/wp\/v2\/comments?post=3411"}],"version-history":[{"count":2,"href":"https:\/\/www.yorku.ca\/professor\/drsmith\/wp-json\/wp\/v2\/posts\/3411\/revisions"}],"predecessor-version":[{"id":3413,"href":"https:\/\/www.yorku.ca\/professor\/drsmith\/wp-json\/wp\/v2\/posts\/3411\/revisions\/3413"}],"wp:attachment":[{"href":"https:\/\/www.yorku.ca\/professor\/drsmith\/wp-json\/wp\/v2\/media?parent=3411"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.yorku.ca\/professor\/drsmith\/wp-json\/wp\/v2\/categories?post=3411"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.yorku.ca\/professor\/drsmith\/wp-json\/wp\/v2\/tags?post=3411"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}