? 7c ?F?_  ) ?3 ?F¥à Q )D P¨ ?F ) ? ???°s ?E )D? ?? P¨? ?F ) ? ?3 ?? e ì¥0 ? ) 3 ?? P¨  7?? ? ) P¨ Vector ? Introducing Arrays myList[0] myList[1] myList[2] myList[3] myList[4] myList[5] myList[6] myList[7] myList[8] myList[9] ?F ^M] ??¥ ? ? ¨?F? ?F ^M] ??¥ ? ? ¨?F? ¥B?ˉ? ? ??YV ?F ¥B?ˉ? ? ??YV ?F ?/S V[ P¨ ?F?¥ ? b ?/S V[ P¨ ?F?¥ ? b /SV /SV 0 7 Sb ?F ^ ?μI?? 7 Sb ?F ^ ?μI?? y?訥 ? 2b y?訥 ? 2b double ??¥ 10? ?Fí í : double[] myList = new double[10] Declaring Arrays )datatype[] arrayname; Example: int[] myList; )datatype arrayname[]; Example: int myList[]; Creating Arrays arrayName = new datatype[arraySize]; Example: myList = new double[10]; Declaring and Creating in One Step )datatype[] arrayname = new datatype[arraySize]; double[] myList = new double[10]; )datatype arrayname[] = new datatype[arraySize]; double myList[] = new double[10]; Initializing Arrays )Using a loop: for (int i = 0; i < myList.length; i++) myList[i] = (double)i; )Declaring, creating, initializing in one step: double[] myList = {1.9, 2.9, 3.4, 3.5}; Example 7.1 Assigning Grades )Objective: read student scores (int) from the keyboard, get the best score, and then assign grades based on the following scheme: – Grade is A if score is >= best–10; – Grade is B if score is >= best–20; – Grade is C if score is >= best–30; – Grade is D if score is >= best–40; – Grade is F otherwise. AssignGrade Run Example 7.2 Using Arrays in Sorting )Objective: Use the selectionSort method to write a program that will sort a list of double floating-point numbers. RunSelectionSort Example 7.3 Testing Linear Search )Objective: Implement and test the linear search method by creating an array of 10 elements of int type randomly and then displaying this array. Prompt the user to enter a key for testing the linear search. RunLinearSearch è 7.4 ? k=s°sE `¥ ?F )Declaring and creating: Circle[] circleArray = new Circle[10]; )Initializing: for (int i=0; i<circleArray.length; i++) { circleArray[i] = new Circle(); } Example 7.5 Summarizing the Areas of Circles )Objective: ?FBF?¥ ?b ? S ??¥??b RunTotalArea ?F¥ˉ? Using a loop: int[] sourceArray = {2, 3, 1, 5, 10}; int[] targetArray = new int[sourceArray.length]; for (int i = 0; i < sourceArrays.length; i++) targetArray[i] = sourceArray[i]; The arraycopy Utility arraycopy(sourceArray, src_pos, targetArray, tar_pos, length); Example: System.arraycopy(sourceArray, 0, targetArray, 0, sourceArray.length); Multidimensional Arrays int[][] matrix = new int[10][10]; or int matrix[][] = new int[10][10]; for (int i=0; i<matrix.length; i++) for (int j=0; j<matrix[i].length; j++) { matrix[i][j] = (int)(Math.random()*1000); } Example 7.7 Adding and Multiplying Two Matrices )Objective: Use two-dimensional arrays to create two matrices, and then add and multiple the two matrices. ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? +++++ +++++ +++++ +++++ +++++ = ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 55555454535352525151 45454444434342424141 35353434333332323131 25252424232322222121 15151412131212121111 5554535251 4544434241 3534333231 2524232221 1514131211 5554535251 4544434241 3534333231 2524232221 1514131211 bababababa bababababa bababababa bababababa bababababa bbbbb bbbbb bbbbb bbbbb bbbbb aaaaa aaaaa aaaaa aaaaa aaaaa Test RunMatrixOperation Numeric Wrapper Classes ) Boolean ) Character ) Short ) Byte ) Long ) Float ) Double Object Double Float Long Integer Short Byte Character BooleanNumber The Integer Class and The Double Class )Constructors )Class Constants MAX_VALUE, MIN_VALUE )Conversion Methods Command-Line Parameters class TestMain { public static void main(String[] args) { ... } } java TestMain arg0, arg1, arg2, ..., argn Processing Command-Line Parameters In the main method, get the arguments from args[0], args[1], ..., args[n], which corresponds to arg0, arg1, ..., argn in the command line. Example 7.8 Using Command-Line Parameters )Objective: Write a program that will perform binary operations on integers. The program receives three parameters: an operator and two integers. Calculator Run java Calculator + 2 3 Run java Calculator - 2 3 Run java Calculator / 2 3 The Vector Class Java provides the Vector class in the java.util package, which can be used to store an unspecified number of elements. A vector can grow or shrink dynamically as needed. The Vector Class, cont. To create a vector, you can use its default constructor like this: Vector vector = new Vector(); To add an element to the vector, use the addElement method as follows: vector.addElement(anObject); The element in the vector must be an object. The element is appended to the vector. The Vector Class, cont. To retrieve an element, use the elementAt method as follows: Object anObject = vector.elementAt(0); To find the number of elements in the vector, use the size method as follows: int numOfElements = vector.size(); Example 7.10 Assigning Grades Using a Vector ) Objective: Rewrites Example 7.1 using a vector, instead of using an array. The program reads student scores from the keyboard, stores the score in the vector, finds the best score, and then assigns grades for all the students. Run AssignGradeUsingVector ˉ5 ) ?? 2 ü?7y ?F$ ) ?F ^B?`? ^B?' ??¥′$ ) ?F 2 üaüs ¥ =i ?$ I 1 H?ó ? Fs ¥ =i$ ) ?F/S¥ ?? ^ I 1$Kl/S ^  $ ) ??7y Vector¥B? L è$ ?¨/ ?¥} ?ísù5 ?¨/ ?¥} ?ísù5 String names[]={“One”, “Two”, “Three”}; String people[]; people=names; ) names [1]¥′ ^ I 1$¥′ ^ I 1$ ) people[2]¥′ ^ I 1$¥′ ^ I 1$ ) / ?} ? {¥ ^ I 1$/ ?} ? {¥ ^ I 1$ – System.out.println(names); ) YV|′YV|′ “One”?1?1 “First” ÷?÷? namesb ) Xü?M  ?FXü?M  ?F names ?F ?F people9? 3M9? 3M ?  ?$ ?  ?$ ) ??| ??| names?¥′ˉ??B??¥M ?$?¥′ˉ??B??¥M ?$ String names[]={“One”, “Two”,“Three”}; String othernames[]=new String[3]; othernames[0] = names[0]; othernames[1] = names[1]; othernames[2] = names[2]; ? System . arrarycopy ( names, 0, othernames, 0, 3); ?D ?D 5?]¥ ^I ?B? ?F7??Y 6B? ?F ?]¥ ^I ?B? ?F7??Y 6B? ?F b