如何从 ListView 中获取所选项目? [英] How to get the selected item from ListView?

问题描述

在我的 Android 应用程序中，我创建了一个名为 myList 的 ListView 组件，并用我自己的自定义类型的对象填充它:

in my Android app I have created a ListView component called myList, and filled it with objects of my own custom type:

class MyClass{

    private String displayName;
    private String theValue;
... //here constructor, getters, setters and toString() are implemented

}

我使用 ArrayAdapter 将 ArrayList theObjects 与 myList 绑定:

I used the ArrayAdapter to bound the ArrayList theObjects with myList:

ArrayAdapter<MyClass> adapter= 
                new ArrayAdapter<MyClass>(this, R.layout.lay_item, theObjects);
myList.setAdapter(adapter);

这很好用，列表已填充等等，但是当我尝试访问所选项目时，我收到一个 Null 对象.我已经使用

This works fine, the list is populated and etc., but when I'm trying to access the selected item, i receive a Null object. I've done this using

myList.setOnItemClickListener(new OnItemClickListener() {

   public void onItemClick(AdapterView<?> adapter, View v, int position, long id) {

MyClass selItem = (MyClass) myList.getSelectedItem(); //
String value= selItem.getTheValue(); //getter method

}

似乎是什么问题?谢谢

推荐答案

默认情况下，当您单击 ListView 项时，它不会将其状态更改为已选择".所以，当事件触发而你这样做时:

By default, when you click on a ListView item it doesn't change its state to "selected". So, when the event fires and you do:

myList.getSelectedItem();

该方法没有任何返回值.你要做的是使用位置并通过以下方式获取底层对象:

The method doesn't have anything to return. What you have to do is to use the position and obtain the underlying object by doing:

myList.getItemAtPosition(position);

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