ArrayList元素拒绝删除

Question

So, I'm making a random Hiragana name generator (don't ask why, okay?) and I've ran into a bit of a problem. The random name generator works fine for the most part but sometimes it generates long strings of repeated consonants for some reason. So instead of trying to address the problem directly like any normal programmer would, I've decided to try and scan through the ArrayList and delete repeated characters after the random generation:

ArrayList<String> name = new ArrayList<String>(); 
Iterator <String> it   = name.iterator();  
...      // insert random generation here                   
for (h = 0; h < s; h++) { // s is the length of the ArrayList
  ...    
  String curInd = name.get(h);
  String nextInd = name.get(h+1);
  if (curInd.equals(nextInd)) { // NOT 
    name.remove(h);             // WORKING
    s--;                        // :(
  }
}

String previousName = "";
while (it.hasNext()) {
String currentName = it.next();
if (currentName.equals(previousName)) {
    it.remove();
}
previousName = currentName;
}

This does not work. I'm not getting an error or anything, it just won't delete the repeated characters (or rather repeated Strings, since I made each character a String.) What could be the problem?

Answer 1

You are changing the indexes as soon as you remove an item. Try using the Iterator.remove() function like the following:

Iterator<String> it = name.iterator();
String previousName = "";

while (it.hasNext()) {
    String currentName = it.next();
    if (currentName.equals(previousName)) {
        it.remove();
    }
    previousName = currentName;
}

Alternatively you can remove all the duplicates with the following one-liner:

names = new ArrayList<String>(new LinkedHashSet<String>(names));

Or even better, use LinkedHashSet or HashSet instead of ArrayList from the very start if you don't want any duplicates.

Answer 2

您应该使用Iterator.remove以便在遍历列表时删除元素。

Answer 3

Index needs to be less than length of List .

 String nextInd = name.get(h+1);

Above statement will throw IndexOutOfBoundsException .

Answer 4

Use HashSet, it automatically removes repeated elements, but sorts elements in alphabetical order.

For Arraylist, Try to use this. This may help.

              int size=headlines.size();
     for (int i = 0; i < size - 1; i++) {
            // start from the next item after strings[i]
            // since the ones before are checked
            for (int j = i + 1; j < size; j++) {
                // no need for if ( i == j ) here
                if (!headlines.get(j).equals(headlines.get(i)))
                    continue;

                headlines.remove(j);
                // decrease j because the array got re-indexed
                j--;
                // decrease the size of the array
                size--;
            } // for j
        } // for i

Answer 5

You could make use of a Set of some kind to automatically remove duplicate elements, for example...

ArrayList<String> name = new ArrayList<String>();
name.add("A");
name.add("A");
name.add("B");
name.add("B");
name.add("B");
name.add("C");
name.add("C");
name.add("C");
System.out.println(name);
Set<String> set = new TreeSet<String>();
set.addAll(name);
System.out.println(set);

This will, of course, remove ALL duplicates, not just those that appear next to each other...

For example...

[A, A, B, B, B, C, C, C]
[A, B, C]

Or...

[A, B, C, B, C, B, C, A]
[A, B, C]

So it might not meet your immediate needs...