java中的这个关键字

声明DataStructure.DataStructureIterator iterator = DataStructure.this.new EvenIterator();是有效的,但在该方法的上下文中是多余的.

考虑这种情况,其中存在冲突的内部类

public void printEven() {
    Thread t = new Thread(new Runnable() {

        @Override
        public void run() {
            //Makes EvenIterator point to DataStructure's implementation
            DataStructureIterator itr = DataStructure.this.new EvenIterator();
        }

        class EvenIterator implements DataStructureIterator {

            @Override
            public boolean hasNext() {
                return false;
            }

            @Override
            public Integer next() {
                return null;
            }

            @Override
            public void remove() {
            }

        }
    });
}

正如您所看到的,匿名类Runnable具有名为内部类的内部类EvenIterator(其名称与外部类的内部类相同).所以写作只是

DataStructureIterator itr = this.new EvenIterator(); //OR DataStructureIterator itr = new EvenIterator();

会参考Runnable的EvenIterator.要指出DataStructure的EvenIterator,你可能会想要写

DataStructureIterator itr = DataStructure.this.new EvenIterator();

哪个说,我想EvenIterator在当前实例上创建DataStructure,而不是当前实例Runnable