字符串搜索与“startsWith（）”

Question

我一直在一个电子邮件目录程序的过去几天，在我的方法之一，我试图做一个搜索功能，搜索电子邮件基于关闭字符输入的用户。我试图让它到达方法循环的地方，并且用户一次只输入一个字符，直到我为此方法构建的数组中只有一个电子邮件。

继承人我的代码：

private void searchContact()  
{ 
    String[] newRecords=new String[emailRecords.size()];  //temp array for searching 
    ArrayList<String> searchRecords=new ArrayList<String>(); //to be passed to insertion sort 
    newRecords=emailRecords.toArray(newRecords);     

    for(String Records: newRecords) 
    { 
     Scanner search=new Scanner(System.in);     //setup for user input 
     String letter; 
     String searchVal; 

     System.out.println("Please enter the first letter of the email you're trying to find."); 
     letter=search.nextLine(); 

     if (searchRecords.size()!=1)  
     { 
      for (int i=0; i<newRecords.length;i++)   //counter for indexes 
      { 
       searchVal=newRecords[i];      //set temp value to set index 

       if (searchVal.startsWith(letter))    //starts with boolean 
       { 
        searchRecords.add(searchVal);    //add to temp array for later comparison 
       } 
      } 
     } 
     else  
     { 
      break;            //break if one remains in the array. 
     } 
    } 
    System.out.println(searchRecords);       //TODO erase when finalizing 
} 

而这里的时候我跑进入开始用相同的字母名称的程序会发生什么：

Please enter the number of your option choice: 
1. Add a new contact 
2. Search for an exsisting contact 
3. Exit 
1 
Please enter the email adress. 
mark 
***mark was successfully stored.*** 
Please enter the number of your option choice: 
1. Add a new contact 
2. Search for an exsisting contact 
3. Exit 
1 
Please enter the email adress. 
mike 
***mike was successfully stored.*** 
Please enter the number of your option choice: 
1. Add a new contact 
2. Search for an exsisting contact 
3. Exit 
1 
Please enter the email adress. 
molly 
***molly was successfully stored.*** 
Please enter the number of your option choice: 
1. Add a new contact 
2. Search for an exsisting contact 
3. Exit 
2 
Please enter the first letter of the email you're trying to find. 
m 
Please enter the first letter of the email you're trying to find. 
a 
Please enter the first letter of the email you're trying to find. 
r 
[mark, mike, molly] 
Please enter the number of your option choice: 
1. Add a new contact 
2. Search for an exsisting contact 
3. Exit 

在这里，我的预期输出后，我在输入信息并尝试通过输入“m”，“a”，“r”和“k”来搜索“标记”：

Please enter the next letter of the email you're trying to find. 
m 
Please enter the next letter of the email you're trying to find. 
a 
Please enter the next letter of the email you're trying to find. 
r 
Please enter the next letter of the email you're trying to find. 
k 
[mark] 

I t在另一个的外侧做另一个循环，这个循环也计算并使用它来移动给定字符串的索引，但是失败了。我觉得我很接近但忽略了一些东西。任何意见或策略将不胜感激！太感谢了。

Answer 1

假设emailRecords包含了所有你的邮件，你的任务是一样的东西：

private void searchContact() { 
    assert(!(emailRecords == null || emailRecords.isEmpty()));// :P 
    //initially copy all 
    ArrayList<String> searchRecords = new ArrayList<>(emailRecords); 
    //prepare scanner 
    Scanner search = new Scanner(System.in); 
    //initialize query 
    String query = ""; 
    //loop: 
    while (searchRecords.size() > 1) { 
     System.out.println("Please enter the first letter of the email you're trying to find."); 
     //read from input 
     query += search.nextLine(); 
     //iterate through remaining searchRecords 
     for (Iterator<String> it = searchRecords.iterator(); it.hasNext();) { 
      final String entry = it.next(); 
      if (!entry.startsWith(query)) {//...conditionally 
       it.remove();//..remove (from searchRecords) 
      } 
     } 
    } 
    //print output - first/last of searchRecords 
    if (!searchRecords.isEmpty()) 
     System.out.println(searchRecords.get(0)); 
    else 
     System.out.println("No record found."); 
} 

Answer 2

有一件事你可以尝试使用特里数据结构来存储的电子邮件地址。 “trie的常见应用是存储预测文本或自动完成字典...”，来自http://en.wikipedia.org/wiki/Trie。