比较字符串与数组字符串和二进制搜索

程序从排序字符串的txt文件中读取，并使用顺序，迭代二进制和递归二进制来存储在数组中，然后搜索数组中的位置以及查找该字所需的迭代次数。 当我尝试将数组中的单词与用户输入的单词进行比较时出错。 不知道为什么。 2）希望有人可以解释迭代二进制和递归二进制之间的差异。 3）为什么有必要这样做……

SearchString si = new SearchString（）;

计划如下……

import ... public class SearchString { public static final String TO_STOP = "-1"; public static final int NOT_FOUND = -1; public static final int MAX_SIZE = 15000; public static int count1; public static int count2; public static int count3; public int sequentialSearch(String[] wordsArray, String word2Search) { int low = 0; int high = wordsArray.length - 1; for (int i = low; i <= high; i++) { count1++; if (wordsArray[i] == word2Search) return i; } return NOT_FOUND; } // end of sequentialSearch() public int binarySearch(String[] wordsArray, String word2Search) { int low = 0; int high = wordsArray.length - 1; while (low  word2Search){ high = mid - 1; } else if (wordsArray[mid]  high) return NOT_FOUND; int mid = (low + high)/2; count3++; if (wordsArray[mid] > word2Search){ return binarySearch2(wordsArray, low, mid-1, word2Search); } else if (wordsArray[mid] < word2Search){ return binarySearch2(wordsArray, mid+1, high, word2Search); } else return mid; } public static void main(String[] args) throws IOException { Scanner keyboard = new Scanner(System.in); boolean wantToContinue = true; Scanner stringsFile = new Scanner (new File("sortedStrings.txt"));//.useDelimiter(",\\s*"); List words = new ArrayList(); String token1 = ""; (stringsFile.hasNext()) { token1 = stringsFile.next(); words.add(token1); } stringsFile.close(); String[] wordsArray = words.toArray(new String[0]); System.out.println(Arrays.toString(wordsArray)); SearchString si = new SearchString(); do { System.out.print("Type a word to search or -1 to stop: "); String word2Search = keyboard.nextLine(); if (word2Search.equals(TO_STOP)){ wantToContinue = false; } else { count1 = count2 = count3 = 0; int index; index = si.sequentialSearch(wordsArray, word2Search); if (index == NOT_FOUND) System.out.println("sequentialSearch() : " + word2Search + " is not found (comparison=" + count1 + ")."); else System.out.println("sequentialSearch() : " + word2Search + " is found in [" + index + "] (comparison=" + count1 + ")."); index = si.binarySearch(wordsArray, word2Search); if (index == NOT_FOUND) System.out.println("iterative binarySearch(): " + word2Search + " is not found (comparison=" + count2 + ")."); else System.out.println("iterative binarySearch(): " + word2Search + " is found in [" + index + "] (comparison=" + count2 + ")."); index = si.binarySearch2(wordsArray, 0, wordsArray.length-1, word2Search); if (index == NOT_FOUND) System.out.println("recursive binarySearch(): " + word2Search + " is not found (comparison=" + count3 + ")."); else System.out.println("recursive binarySearch(): " + word2Search + " is found in [" + index + "] (comparison=" + count3 + ")."); } } while (wantToContinue); } 

}

Answer 1

您无法将String与== （或>和< ）进行比较。 您需要使用String.compareTo

Answer 2

如何比较String s（或任何其他类型的Comparable对象）：

• a > b变为a.compareTo(b) > 0
• a < b变为a.compareTo(b) < 0
• a == b变为a.equals(b)