循環直到用戶輸入長度小於或等於先前用戶輸入

Question

import java.util.Scanner; 

public class userInputTest { 

    public static void main(String[] args) { 

     Scanner sc = new Scanner(System.in); 

     for(int i = 0; i>-1; i=i+1){ 

      String[] giveMeAString = new String[i+1]; 
      String x = sc.next(); 

      giveMeAString[i]=x; 

      if(i>=0){ 
       if (giveMeAString[i].length() < giveMeAString[i-1].length()){ 
        System.out.println("The string is shorter than previous string!"); 
        break;} 
      } 

     } 

    } 
} 

我想循環直到當前用戶輸入長度小於先前用戶輸入長度。

許多嘗試後，我還沒有解決它。

我做錯了什麼？ 我想使用Array，因爲我也想稍後打印出用戶輸入。

我現在唯一的問題是使書面代碼工作。

Answer 1

幾件事情需要注意：

1. 你重置您的每一次陣列，作爲聲明（內存分配）是在「for」循環
的第（i + 1）將分配
2. 數組大小當你嘗試更多次數時，很多內存
3. giveMeAString [i-1]：i = 1 - 這應該是你的for（）的起點。否則，你會得到arrayIndexOutOfBound異常，因爲當i = 0時你將訪問giveMeAString [-1]。這是不存在的數組位置/ element-index。
4. 如果你想比較2個連續的字符串長度，你需要確保在循環的第一次迭代時，你至少有2個字符串填充（或檢查你是否在第一次迭代，然後繼續循環添加第二個字符串沒有進一步）。

更正代碼：

Scanner sc = new Scanner(System.in); 

     //arrays are alaways static memory allocation constructs. First input should always be the array size. If this is not known 
     //ahead of time, use List, ArrayList etc. 
     int a; 
     System.out.println("Enter Array size in number: "); 
     a = sc.nextInt(); 
     String[] giveMeAString = new String[a]; 
     String x; 

     //updaing the loop initialization and condition 
     for(int i = 1; i>0; i=i+1){ 

      //should NOT be creating array every time. Strings are immutable and hence costly w.r.t. memory/responseTime. 
      //Besides, i didn't understand the logic of creating array of String of size (i+1). 
      //instead, consider using resizable list (ArrayList etc). Below line is resetting your previously input values in giveMeAString[] 
      //String[] giveMeAString = new String[i+1]; 


      if (i == 1) { 
       //adding first input to array's first index. Without this, we would get NPE. One time execution. 
       x = sc.next(); 
       giveMeAString[i - 1] = x; 
      } 

      //adding next input to array's next index 
      x = sc.next(); 
      giveMeAString[i]= x; 

      if(i>=0){ 
       if (giveMeAString[i].length() < giveMeAString[i-1].length()){ 
        System.out.println("The string is shorter than previous string!"); 
        break; 
       } 
      } 

     } 

Answer 2

一如以往的答案，但使用ArrayList實現中，如果數組的大小不應該被限制。

Scanner scn = new Scanner(System.in); 
    List<String> strList = new ArrayList<>(); 

    /* 
    * First clase to allow logic receive at least 1 input without performing the check. 
    * Next clause to check if current input length is greater than previous input length, continue receiving input 
    */ 
    while (strList.size() < 2 || strList.get(strList.size() - 1 ).length() 
      >= strList.get(strList.size() - 2).length()) 
    { 
     System.out.println(" Enter new String: "); 
     strList.add(scn.next()); 
    } 

    System.out.println("Previous String is shorter."); 
    scn.close(); 

    System.out.println(Arrays.toString(strList.toArray())); 

更新，使用數組實現。

Scanner scn = new Scanner(System.in); 
String [] strArray = new String[0]; 

/* 
* First clause to allow logic receive at least 1 input without 
* performing the check. Next clause to check if current input length is 
* greater than previous input length, continue receiving input 
*/ 
while (strArray.length < 2 
    || strArray[strArray.length - 1].length() >= strArray[strArray.length -2].length()) 
{ 
    String[] tempArr = new String[strArray.length + 1]; 
    for(int i = 0; i < strArray.length; i++){ 
     tempArr[i] = strArray[i]; 
    } 
    strArray = tempArr; 
    System.out.println(" Enter new String: "); 
    strArray[strArray.length - 1] = scn.next(); 
} 

System.out.println("Previous String is shorter."); 
scn.close(); 

System.out.println(Arrays.toString(strArray));