Question

我是android的新手，我正在尝试创建一个自定义列表视图，在每个行中都有多个文本视图。为此我创建了一个自定义列表适配器，通过扩展ArrayListAdapter并覆盖getView方法并将适配器设置为在我的主要活动中列出适应器。但是每次我运行app listview都拒绝填充。

Start.java

public class Start extends Activity {
String jasonString="[{\"name\": \"abc\",\n" +
        "\"address\":\"Delhi\",\n" +
        "\"email\":\"abc@gmail.com\"},{\"name\": \"def\",\n" +
        "\"address\":\"Delhi\",\n" +
        "\"email\":\"def@gmail.com\"},{\"name\": \"ghi\",\n" +
        "\"address\":\"ferf\",\n" +
        "\"email\":\"ghi@gmail.com\"},{\"name\": \"jkl\",\n" +
        "\"address\":\"Delheri\",\n" +
        "\"email\":\"jkl@gmail.com\"}\n" +
        ",{\"name\": \"mno\",\n" +
        "\"address\":\"Delhi\",\n" +
        "\"email\":\"mno@gmail.com\"},{\"name\": \"pqr\",\n" +
        "\"address\":\"Delhi\",\n" +
        "\"email\":\"pqr@gmail.com\"}]\n";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    Log.i("mee","Activity created.");
    ListView lv= (ListView) findViewById(R.id.list1);
    ArrayList<Model> list=new ArrayList<>();
    JsonArray array=new JsonParser().parse(jasonString).getAsJsonArray();
    for(JsonElement element:array){
        Model mod=new Gson().fromJson(element,Model.class);
        list.add(mod);
    }

    Log.i("mee","List size"+list.size());
    for(Model mod:list){
        Log.i("mee", "name:" + mod.name);
    }

    CustomListAdapter adapter=new CustomListAdapter(this,R.layout.row_item,list);
    lv.setAdapter(adapter);



        }
   }

CustomListAdapter.class

public class CustomListAdapter extends ArrayAdapter<Model>{

private Context mContext;
private ArrayList<Model> mObjects;

public CustomListAdapter(Context context, int resource,ArrayList<Model> objects) {
    super(context, resource, objects);
    mContext=context;
    mObjects=objects;
    // TODO Auto-generated constructor stub
    }
    @Override
   public View getView(int position, View convertView, ViewGroup parent)
  {
      Log.i("meee","inside CustomListAdapter, getView");
    if (convertView == null) {
        LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = inflater.inflate(R.layout.row_item, parent, false);
    }
    ((TextView) convertView.findViewById(R.id.textView1)).setText(mObjects.get(position).name);
    ((TextView) convertView.findViewById(R.id.textView2)).setText(mObjects.get(position).address);
    ((TextView) convertView.findViewById(R.id.textView3)).setText(mObjects.get(position).sex);
    return convertView;
}
}

row_item.xml

<?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="wrap_content"
android:orientation="horizontal" >

<TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="TextView" />

<TextView
    android:id="@+id/textView2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="TextView" />

<TextView
    android:id="@+id/textView3"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="TextView" />

</LinearLayout>

main.xml中

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:text="This is the main layout"/>
<ListView
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:id="@+id/list1"></ListView>

</LinearLayout>

有人可以告诉我，我做错了什么？我没有收到任何错误，数据列表总是可用的数据。

Answer 1

我已经尝试过您的代码了。将您的main.xml布局更改为如下所示。

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    >
  <TextView
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:text="This is the main layout"
      />
  <ListView
      android:layout_weight="1"
      android:layout_width="match_parent"
      android:layout_height="0dp"
      android:id="@+id/list1"
      />

</LinearLayout>

它对我有用。

Answer 2

在main.xml中，您将textview设置为android:layout_height="fill_parent"，因此textview将从上到下占据整个屏幕，不会显示ListView的空间。

将其更改为android:layout_height="wrap_content"，它应该有效。

Listview不会出现

2 个答案: