JAVA - 从迭代列表中删除非迭代器元素

Question

我在遍历此迭代器循环时遇到问题，在该循环中我遍历了 this.env 的每个元素，但在此列表中，我想删除所述列表的不同元素。当我尝试删除所述迭代列表的任何项目时，我收到此错误:java.util.ConcurrentModificationException，据我所知，这是由于在不使用 iterator.remove 的情况下修改迭代列表造成的().

代码:

public void envActions(IOHandler ioHandler, PlayerClass player){
    Iterator<WorldElement> worldElementIterator = this.env.iterator();
    while(worldElementIterator.hasNext()){
        WorldElement worldElement = worldElementIterator.next();
    //for(WorldElement worldElement:this.env){
        if(worldElement instanceof EntityClass){
            EntityClass entity=(EntityClass) worldElement;
            if(entity.nature.contains("hostile")){
                MonsterClass mEntity=(MonsterClass) entity;
                if(!(mEntity.attacks.size()*(Math.random()+0.25)>=mEntity.attacks.size())){
                    Double followerNum = (Math.random()*player.followers.size());
                    Integer followerNumInt=followerNum.intValue();
                    if(followerNumInt<2){
                        PlayerClass target=player;
                        Double attacknumD=mEntity.attacks.size()*Math.random();
                        Integer attacknum= attacknumD.intValue();
                        Integer playerarmor=player.getArmorValue();
                        int enemydamage=mEntity.attacks.get(attacknum).getDamage()*(1-(playerarmor/1000));
                        target.health=target.health-enemydamage;
                        ioHandler.printToConsole("\nThe "+mEntity.name+" attacked you with "+mEntity.attacks.get(attacknum).getAttack()+" and did "+mEntity.attacks.get(attacknum).getDamage()+" damage! you have "+player.health+" health left!");
                    } else {
                        FriendlyCreatureClass target=player.followers.get(followerNumInt);
                        Double attacknumD=mEntity.attacks.size()*Math.random();
                        Integer attacknum= attacknumD.intValue();
                        int enemydamage=mEntity.attacks.get(attacknum).getDamage();
                        target.health=target.health-enemydamage;
                        if(!target.isAlive()){
                            ioHandler.printToConsole("\nThe " + mEntity.name + " attacked " + target.name + " with " + mEntity.attacks.get(attacknum).getAttack() + " and did " + mEntity.attacks.get(attacknum).getDamage() + " damage! " + target.name+" died! Farewell "+target.name+".");
                            target.died(ioHandler, this, player, true);
                            //>>>> THIS IS WHERE I WOUlD LIKE TO REMOVE 'target' FROM THE env LIST <<<<
                        } else {
                            ioHandler.printToConsole("\nThe "+mEntity.name+" attacked "+target.name+" with "+mEntity.attacks.get(attacknum).getAttack()+" and did "+mEntity.attacks.get(attacknum).getDamage()+" damage! "+target.name+" has "+target.health+" health left!");
                        }
                    }
                }

请怜悯我的编码技能，因为我只是 java/Android 的初学者，但非常感谢任何建议!

提前致谢!

Answer 1

如果您出于某种原因未使用 Iterator，则可以在迭代集合时将要删除的元素收集到 Set 中，并在循环之后迭代 Set 并从原始集合中删除元素。

请注意，这仅适用于小型集合。

HashSet toDelete = new HashSet();

for (...) {
    if (...)
       toDelete.add(item);
}
// end for

foreach (item in toDelete) {
    // delete from original collection
}

否则，您可以在迭代器上调用 remove()。