java如何反转ArrayList

Question

我需要撤销我的内容列表。我找到了^{，但不知道如何正确地实现它

private class MyFilter extends Filter {

    @Override
    protected FilterResults performFiltering(CharSequence constraint) {

        FilterResults oReturn = new FilterResults();
        ArrayList<Advice> results = new ArrayList<Advice>();

        if (orig == null)
            orig = list;

        if (constraint != null) {
            if (orig != null) {
                for (Advice d : orig) {
                    if ((d.getTitle() + " " + d.getText()).toLowerCase()
                            .contains(constraint.toString())) {
                        results.add(d);
                    }
                }
            }
        }

        list = results;

        return oReturn;
    }

    @Override
    protected void publishResults(CharSequence constraint,
            FilterResults results) {
        notifyDataSetChanged();
    }
}

Answer 1

添加解析器的最佳方式：

Collections.reverse(data);
System.out.println(data.toString());

Answer 2

更改代码如下： 私有类MyFilter扩展了筛选器{

@Override
protected FilterResults performFiltering(CharSequence constraint) {

    FilterResults oReturn = new FilterResults();
    ArrayList<Advice> results = new ArrayList<Advice>();

    if (orig == null)
        orig = list;

    if (constraint != null) {
        if (orig != null) {
            for (Advice d : orig) {
                if ((d.getTitle() + " " + d.getText()).toLowerCase()
                        .contains(constraint.toString())) {
                    results.add(d);
                }
            }
        }
    }

    Collections.reverse(results);
    oReturn.values = results;
    oReturn.count = results.size();

    return oReturn;
}

@Override
protected void publishResults(CharSequence constraint,
        FilterResults results) {
    notifyDataSetChanged();
}

}

希望能有所帮助

Answer 3

简单地说：

  // Create the list
  ArrayList<String> myList = new ArrayList<String>();

  // Add some items to it
  myList.add("one");
  myList.add("two");
  myList.add("three");

  // Reverse it by using Collections utilities.
  Collections.reverse(myList);

  Log.i("DEBUG", myList.get(0)); // Should print 'three' 

Answer 4

你应该进口

import java.util.Collections;

然后使用

Collections.reverse(results);

Answer 5

如果想要添加符合条件的元素，但没有java8或任何函数库，可以在构造循环后将其反转，或者在遍历之前反转原始元素。或者在施工过程中以相反的顺序穿过它。使用索引的示例如下：

for(int i = orig.size()-1; i >-1; i--) {
    //add matching elements to the newly constructed list.
}