使用迭代器从列表中删除条目

问题描述

我需要编写一个简单的函数来删除 List 中包含 Elem 类的对象的所有条目.我写了removeAllElements这个函数，但是如果List的大小大于1就不行了.

I need to write a simple function that will delete all entries in the List that contains objects of the class Elem. I wrote the function removeAllElements, but it does not work if the size of the List<Elem> is greater than 1.

public class Test {

public static void main(String[] args) {
        Work w = new Work();
        w.addElement(new Elem("a",new Integer[]{1,2,3}));
        w.addElement(new Elem("b",new Integer[]{4,5,6}));

        w.removeAllElements(); // It does not work for me.
    }
}

public class Work {

    private List<Elem> elements = new ArrayList<Elem>();

    public void addElement(Elem e) {
        this.elements.add(e);
    }

    public void removeAllElements() {
        Iterator itr = this.elements.iterator();
        while(itr.hasNext()) {
            Object e = itr.next();
            this.elements.remove(e);
        }
    }

}

public class Elem {

    private String title;
    private Integer[] values;

    public Elem(String t,Integer v) {
        this.title = t;
        this.values = v;
    }

}

编辑#1错误信息如下:

Exception in thread "AWT-EventQueue-0" java.util.ConcurrentModificationException
    at java.util.AbstractList$Itr.checkForComodification(Unknown Source)
    at java.util.AbstractList$Itr.next(Unknown Source)

推荐答案

代码无法编译.什么是this.tokens?

The code doesn't compile. What is this.tokens?

无论如何，如果你想在迭代时移除一个元素，你必须使用迭代器的remove方法来完成:

Anyway, if you want to remove an element while iterating, you must do it using the iterator's remove method:

itr.next();
itr.remove();

不过，您的 removeAllElements 方法可以只执行 this.elements.clear().更加直接和高效.

Your removeAllElements method could just do this.elements.clear(), though. Much more straightforward and efficient.

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