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Java 单击按钮将项目从arraylist添加到listview_Java_Android_Listview_Button_Android Listview - Fatal编程技术网

Java 单击按钮将项目从arraylist添加到listview

Java 单击按钮将项目从arraylist添加到listview,java,android,listview,button,android-listview,Java,Android,Listview,Button,Android Listview,我有一个arraylistList myCars=new arraylist()我的MainActivity布局有一个listview和一个按钮。还有一个布局(“each_car.xml”),其内容如下:- <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width=

我有一个arraylist
List myCars=new arraylist()我的MainActivity布局有一个listview和一个按钮。还有一个布局(“each_car.xml”),其内容如下:-

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
 <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"  >

        <TextView
            android:id="@+id/tv_carName"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="TextView" />

        <TextView
            android:id="@+id/tv_carMaker"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="TextView" />
    </LinearLayout>
</LinearLayout>
我通过异步任务填充此列表(myCars)。任务完成后,即在onPostExecute()内,我将调用MainActivity中的一个方法,该方法将使用列表中的项目填充listview。方法如下:-

public void populateListView(List<Cars> data){

    ArrayAdapter<Cars> carAdapter = new CarAdapter(MainActivity.this, data);
    ListView dataList = (ListView) findViewById(R.id.car_listView);
    dataList.setAdapter(carAdapter);    
}
public void populateListView(列表数据){
ArrayAdapter carAdapter=新的carAdapter(MainActivity.this,data);
ListView数据列表=(ListView)findViewById(R.id.car\u ListView);
dataList.setAdapter(carAdapter);
}
以下是我的CarAdapter课程:-

public class CarAdapter extends ArrayAdapter<Cars>{

    private LayoutInflater inflater;
    List<Cars> dummyData = new ArrayList<Cars>();
    MainActivity host;

    public CarAdapter(MainActivity host, List<Cars> data)
    {
        super(host,R.layout.each_car,data);
        inflater = host.getWindow().getLayoutInflater();
        dummyData = data;

    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent)
    {

        View itemView = convertView;

        if(itemView == null)
        {
            itemView = inflater.inflate(R.layout.each_car,parent,false);
        }

        Cars currentData = dummyData.get(position);
        Log.d("Testing Position","Position :- "+position);
        TextView carName = (TextView) itemView.findViewById(R.id.tv_carName);
        carName.setText(currentData.getName());
        TextView carMaker = (TextView) itemView.findViewById(R.id.tv_carMaker);
        carMaker.setText(currentData.getManufacturer());
        return itemView;
    }
}
公共类CarAdapter扩展了ArrayAdapter{
私人充气机;
List dummyData=newarraylist();
主活动主机;
公共适配器(主活动主机,列表数据)
{
超级(主机、右布局、每辆车、数据);
充气机=host.getWindow().getLayoutFlater();
dummyData=数据;
}
@凌驾
公共视图getView(int位置、视图转换视图、视图组父视图)
{
视图项视图=转换视图;
如果(itemView==null)
{
itemView=充气机。充气(右布局。每辆车,父车,假);
}
Cars currentData=dummyData.get(位置);
Log.d(“测试位置”,“位置:-”+位置);
TextView carName=(TextView)itemView.findViewById(R.id.tv\u carName);
carName.setText(currentData.getName());
TextView汽车制造商=(TextView)itemView.findViewById(R.id.tv_汽车制造商);
automaker.setText(currentData.getManufacturer());
返回项目视图;
}
}
这是一次用整个列表(myCars)填充listview


问题:-单击按钮时,我想一次用一个项目填充listView。我不确定如何修改代码。

在主布局上创建一个按钮。为按钮实现onclicklistener,并在onClick方法内调用populateListView()


创建一个新列表。单击按钮时,将项目添加到新列表中。调用notifydatasetchanged()。单击按钮时,请检查项目是否已添加到新列表中。在适配器中使用新创建的列表,以便每次添加新项时都可以使用

单击按钮并调用
carAdapter.notifyDataSetChanged()

Hi-Shriram,在单击按钮时调用populateListView()有什么区别。问题在于调用populateListView()时,它将用整个arraylist(myCars)项填充listview。请参见保留两个列表,一个是包含所有项的列表,另一个是附加到listview的列表(在您的示例中是数据),我将它们称为list1和data。最初,数据只有一项。单击按钮时,将列表1中的一项添加到数据并调用
carAdapter.notifyDataSetChanged()
或使用新数据列表调用setadapter(第二次包含两项)。
public class CarAdapter extends ArrayAdapter<Cars>{

    private LayoutInflater inflater;
    List<Cars> dummyData = new ArrayList<Cars>();
    MainActivity host;

    public CarAdapter(MainActivity host, List<Cars> data)
    {
        super(host,R.layout.each_car,data);
        inflater = host.getWindow().getLayoutInflater();
        dummyData = data;

    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent)
    {

        View itemView = convertView;

        if(itemView == null)
        {
            itemView = inflater.inflate(R.layout.each_car,parent,false);
        }

        Cars currentData = dummyData.get(position);
        Log.d("Testing Position","Position :- "+position);
        TextView carName = (TextView) itemView.findViewById(R.id.tv_carName);
        carName.setText(currentData.getName());
        TextView carMaker = (TextView) itemView.findViewById(R.id.tv_carMaker);
        carMaker.setText(currentData.getManufacturer());
        return itemView;
    }
}