文件名称：Java大学教程
文件大小：5KB
文件格式：JAVA
更新时间：2016-02-27 14:14:39
大学教程
import java.util.*; // a menu driven program to test a selection of useful array methods public class SomeUsefulArrayMethods { public static void main (String[] args) { char choice; Scanner sc = new Scanner(System.in); int[] someArray; // declare an integer array System.out.print("How many elements to store?: "); int size = sc.nextInt(); // size the array someArray = new int [size]; // menu do { System.out.println(); System.out.println("[1] Enter values"); System.out.println("[2] Array maximum"); System.out.println("[3] Array sum"); System.out.println("[4] Array membership"); System.out.println("[5] Array search"); System.out.println("[6] Display values"); System.out.println("[7] Exit"); System.out.print("Enter choice [1-7]: "); choice = sc.next().charAt(0); System.out.println(); // process choice by calling helper methods switch(choice) { case '1': fillArray(someArray); break; case '2': int max = max(someArray); System.out.println("Maximum array value = " + max); break; case '3': int total = sum(someArray); System.out.println("Sum of array values = " + total); break; case '4': System.out.print ("Enter value to find: "); int value = sc.nextInt(); boolean found = contains(someArray, value); if (found) { System.out.println(value + " is in the array"); } else { System.out.println(value + " is not in the array"); } break; case '5': System.out.print ("Enter value to find: "); int item = sc.nextInt(); int index = search(someArray, item); if (index == -999) // indicates value not found { System.out.println ("This value is not in the array"); } else { System.out.println ("This value is at array index " + index); } break; case '6': System.out.println("Array values"); displayArray(someArray); break; } } while (choice != '7'); System.out.println("Goodbye"); } // helper methods // fills an array with values public static void fillArray(int[] arrayIn) { Scanner sc = new Scanner (System.in); for (int i = 0; i < arrayIn.length; i++) { System.out.print("enter value "); arrayIn[i] = sc.nextInt(); } } // returns the total of all the values held within an array private static int sum (int[] arrayIn) { int total = 0; for (int currentElement : arrayIn) { total = total + currentElement; } return total; } // returns the maximum value in an array private static int max (int[] arrayIn) { int result = arrayIn[0]; for (int currentElement : arrayIn) { if (currentElement > result) { result = currentElement; } } return result; } // checks whether or not an item is contained within an array private static boolean contains (int[] arrayIn, int valueIn) { for (int currentElement : arrayIn) { if (currentElement == valueIn) { return true; } } return false; } /* returns the position of an item within an array or -999 if the value is not present within the array */ private static int search (int[] arrayIn, int valueIn) { for (int i=0; i < arrayIn.length; i++) { if (arrayIn[i] == valueIn) { return i; } } return -999; } // displays the array values on the screen public static void displayArray(int[] arrayIn) { System.out.println(); // standard 'for' loop used here as the array index is required for (int i = 0; i < arrayIn.length; i++) { System.out.println("array[" + i + "] = " + arrayIn[i]); } } }