从数组列表中删除项

我有一个 ArrayList假设 list，它有8个项目 A-H，现在我想删除1,3,5位置项目存储在整型数组从 list如何做到这一点。

我正在努力做到这一点

ArrayList<String> list = new ArrayList<String>();
list.add("A");
list.add("B");
list.add("C");
list.add("D");
list.add("E");
list.add("F");
list.add("G");
list.add("H");


int i[] = {1,3,5};


for (int j = 0; j < i.length; j++) {
list.remove(i[j]);
}

但是在第一个项目删除数组的位置被改变，并在下一次迭代它删除错误的元素或给予异常。

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最佳答案

In this specific case, you should remove the elements in descending order. First index 5, then 3, then 1. This will remove the elements from the list without undesirable side effects.

for (int j = i.length-1; j >= 0; j--) {
list.remove(i[j]);
}
小开 
String[] mString = new String[] {"B", "D", "F"};


for (int j = 0; j < mString.length-1; j++) {
List_Of_Array.remove(mString[j]);
}
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How about this? Just give it a thought-

import java.util.ArrayList;


class Solution
{
public static void main (String[] args){


ArrayList<String> List_Of_Array = new ArrayList<String>();
List_Of_Array.add("A");
List_Of_Array.add("B");
List_Of_Array.add("C");
List_Of_Array.add("D");
List_Of_Array.add("E");
List_Of_Array.add("F");
List_Of_Array.add("G");
List_Of_Array.add("H");


int i[] = {1,3,5};


for (int j = 0; j < i.length; j++) {
List_Of_Array.remove(i[j]-j);
}


System.out.println(List_Of_Array);


}




}

And the output was-

[A, C, E, G, H]
小开

You can remove elements from ArrayList using ListIterator,

ListIterator listIterator = List_Of_Array.listIterator();


/* Use void remove() method of ListIterator to remove an element from List.
It removes the last element returned by next or previous methods.
*/
listIterator.next();


//remove element returned by last next method
listIterator.remove();//remove element at 1st position
listIterator.next();
listIterator.next();
listIterator.remove();//remove element at 3rd position
listIterator.next();
listIterator.next();
listIterator.remove();//remove element at 5th position
小开

Try it this way,

ArrayList<String> List_Of_Array = new ArrayList<String>();
List_Of_Array.add("A");
List_Of_Array.add("B");
List_Of_Array.add("C");
List_Of_Array.add("D");
List_Of_Array.add("E");
List_Of_Array.add("F");
List_Of_Array.add("G");
List_Of_Array.add("H");


int i[] = {5,3,1};


for (int j = 0; j < i.length; j++) {
List_Of_Array.remove(i[j]);
}
小开 
 public void DeleteUserIMP(UserIMP useriamp) {
synchronized (ListUserIMP) {
if (ListUserIMP.isEmpty()) {
System.out.println("user is empty");
}  else {
Iterator<UserIMP> it = ListUserIMP.iterator();
while (it.hasNext()) {
UserIMP user = it.next();
if (useriamp.getMoblieNumber().equals(user.getMoblieNumber())) {
it.remove();
System.out.println("remove it");
}
}
// ListUserIMP.remove(useriamp);


System.out.println(" this user removed");
}
Constants.RESULT_FOR_REGISTRATION = Constants.MESSAGE_OK;
// System.out.println("This user Deleted " + Constants.MESSAGE_OK);


}
}
小开

If you use "=", a replica is created for the original arraylist in the second one, but the reference is same so if you change in one list , the other one will also get modified. Use this instead of "="

        List_Of_Array1.addAll(List_Of_Array);
小开

As mentioned before

iterator.remove()

is maybe the only safe way to remove list items during the loop.

For deeper understanding of items removal using the iterator, try to look at this thread

小开

remove(int index) method of arraylist removes the element at the specified position(index) in the list. After removing arraylist items shifts any subsequent elements to the left.

Means if a arraylist contains {20,15,30,40}

I have called the method: arraylist.remove(1)

then the data 15 will be deleted and 30 & 40 these two items will be left shifted by 1.

For this reason you have to delete higher index item of arraylist first.

So..for your given situation..the code will be..

ArrayList<String> list = new ArrayList<String>();
list.add("A");
list.add("B");
list.add("C");
list.add("D");
list.add("E");
list.add("F");
list.add("G");
list.add("H");


int i[] = {1,3,5};


for (int j = i.length-1; j >= 0; j--) {
list.remove(i[j]);
}
小开

I assume the array i is ascend sorted, here is another solution with Iterator, it is more generic:

ArrayList<String> list = new ArrayList<String>();
list.add("A");
list.add("B");
list.add("C");
list.add("D");
list.add("E");
list.add("F");
list.add("G");
list.add("H");


int i[] = {1,3,5};


Iterator<String> itr = list.iterator();
int pos = 0;
int index = 0;
while( itr.hasNext() ){
itr.next();
if( pos >= i.length ){
break;
}
if( i[pos] == index ){
itr.remove();
pos++;
}


index++;
}
小开

if you need to remove end item in list can use this code

 if(yourList.size() != 0){
yourList.remove(yourList.size()-1);
}

or maybe you need to remove a time after select item in list

if(selected){// boolean for checked add or remove
yourList.add(position , id); // add to list by position can use your list position
}else{
if(yourList.size() != 0){
yourList.remove(position);
}
}

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