我试图将数据库转换为ListView，并在点击时显示更多信息，但是一旦我添加了可扩展功能，我就开始在标题中收到错误。< / p>
这是我的list_item.xml，似乎是问题的根源：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:padding="@dimen/activity_horizontal_margin">
<TextView
android:id="@+id/name"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:paddingBottom="2dip"
android:textColor="@color/colorAccent"/>
<View
android:layout_width="0px"
android:layout_height="0px"
android:id="@+id/expandable">
<TextView
android:id="@+id/description"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="#5d5d5d"
android:textStyle="bold"/>
<TextView
android:id="@+id/email"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="#5d5d40"
android:textStyle="bold" />
<TextView
android:id="@+id/telephone"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="#5d5d40"
android:textStyle="bold" />
</View>
</LinearLayout>
这里是MainActivity2.java（临时名称）：
public class MainActivity2 extends Activity {
private String TAG = MainActivity2.class.getSimpleName();
private ListView lv;
private View ex;
ArrayList<HashMap<String, String>> contactList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
contactList = new ArrayList<>();
lv = (ListView) findViewById(R.id.list);
new GetContacts().execute();
ex = findViewById(R.id.expandable);
lv.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
public void onItemSelected(AdapterView parentView, View childView,
int position, long id)
{
expand(ex);
}
public void onNothingSelected(AdapterView parentView) {
}
});
}
public static void expand(final View v) {
v.measure(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT);
final int targetHeight = v.getMeasuredHeight();
// Older versions of android (pre API 21) cancel animations for views with a height of 0.
v.getLayoutParams().height = 1;
v.setVisibility(View.VISIBLE);
Animation a = new Animation()
{
@Override
protected void applyTransformation(float interpolatedTime, Transformation t) {
v.getLayoutParams().height = interpolatedTime == 1
? LinearLayout.LayoutParams.WRAP_CONTENT
: (int)(targetHeight * interpolatedTime);
v.requestLayout();
}
@Override
public boolean willChangeBounds() {
return true;
}
};
// 1dp/ms
a.setDuration((int)(targetHeight / v.getContext().getResources().getDisplayMetrics().density));
v.startAnimation(a);
}
public static void collapse(final View v) {
final int initialHeight = v.getMeasuredHeight();
Animation a = new Animation()
{
@Override
protected void applyTransformation(float interpolatedTime, Transformation t) {
if(interpolatedTime == 1){
v.setVisibility(View.GONE);
}else{
v.getLayoutParams().height = initialHeight - (int)(initialHeight * interpolatedTime);
v.requestLayout();
}
}
@Override
public boolean willChangeBounds() {
return true;
}
};
// 1dp/ms
a.setDuration((int)(initialHeight / v.getContext().getResources().getDisplayMetrics().density));
v.startAnimation(a);
}
private class GetContacts extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
super.onPreExecute();
Toast.makeText(MainActivity2.this,"Json Data is downloading",Toast.LENGTH_LONG).show();
}
@Override
protected Void doInBackground(Void... arg0) {
HttpHandler sh = new HttpHandler();
// Making a request to url and getting response
String url = "https://s3-eu-west-1.amazonaws.com/tyi-work/Work_Experience.json";
String jsonStr = sh.makeServiceCall(url);
Log.e(TAG, "Response from url: " + jsonStr);
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr);
// Getting JSON Array node
JSONArray contacts = jsonObj.getJSONArray("work");
// looping through All Contacts
for (int i = 0; i < contacts.length(); i++) {
JSONObject c = contacts.getJSONObject(i);
String id = c.getString("id");
String name = c.getString("name");
String email = c.getString("email");
String address = c.getString("address");
String telephone = c.getString("telephone");
// Phone node is JSON Object
String description = c.getString("description");
String agerange = c.getString("agerange");
String county = c.getString("county");
String category = c.getString("category");
String website = c.getString("website");
// tmp hash map for single contact
HashMap<String, String> contact = new HashMap<>();
// adding each child node to HashMap key => value
contact.put("description", description);
contact.put("name", name);
contact.put("email", email);
contact.put("telephone", telephone);
// adding contact to contact list
contactList.add(contact);
}
} catch (final JSONException e) {
Log.e(TAG, "Json parsing error: " + e.getMessage());
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(getApplicationContext(),
"Json parsing error: " + e.getMessage(),
Toast.LENGTH_LONG).show();
}
});
}
} else {
Log.e(TAG, "Couldn't get json from server.");
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(getApplicationContext(),
"Couldn't get json from server. Check LogCat for possible errors!",
Toast.LENGTH_LONG).show();
}
});
}
return null;
}
@Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
ListAdapter adapter = new SimpleAdapter(MainActivity2.this, contactList,
R.layout.list_item, new String[]{ "email","description","name"},
new int[]{R.id.email, R.id.description, R.id.name});
lv.setAdapter(adapter);
}
}
}
如果需要更多信息，我很乐意提供。
提前谢谢
编辑：
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.teamplum.projectapple, PID: 12076
java.lang.ClassCastException: android.view.View cannot be cast to android.view.ViewGroup
at android.view.LayoutInflater.rInflate(LayoutInflater.java:826)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:828)
at android.view.LayoutInflater.inflate(LayoutInflater.java:523)
at android.view.LayoutInflater.inflate(LayoutInflater.java:425)
at android.widget.SimpleAdapter.createViewFromResource(SimpleAdapter.java:121)
at android.widget.SimpleAdapter.getView(SimpleAdapter.java:114)
at android.widget.AbsListView.obtainView(AbsListView.java:2481)
at android.widget.ListView.measureHeightOfChildren(ListView.java:1289)
at android.widget.ListView.onMeasure(ListView.java:1197)
at android.view.View.measure(View.java:17970)
at android.widget.RelativeLayout.measureChild(RelativeLayout.java:816)
at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:561)
at android.view.View.measure(View.java:17970)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5710)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:465)
at android.view.View.measure(View.java:17970)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5710)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1723)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:785)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:654)
at android.view.View.measure(View.java:17970)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5710)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:465)
at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2755)
at android.view.View.measure(View.java:17970)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2438)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1418)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1642)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1296)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6742)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:826)
at android.view.Choreographer.doCallbacks(Choreographer.java:629)
at android.view.Choreographer.doFrame(Choreographer.java:597)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:812)
at android.os.Handler.handleCallback(Handler.java:815)
at android.os.Handler.dispatchMessage(Handler.java:104)
at android.os.Looper.loop(Looper.java:194)
at android.app.ActivityThread.main(ActivityThread.java:5931)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:987)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:782)
答案 0 :(得分：1)
此错误表示您将视图放在<View>中。将此视图更改为ViewGroup（例如linearLayout或RelativeLayout），您的问题就会消失。
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:padding="@dimen/activity_horizontal_margin">
<TextView
android:id="@+id/name"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:paddingBottom="2dip"
android:textColor="@color/colorAccent"/>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent" <!-- edit this height and width-->
<!--also add orientation-->
android:id="@+id/expandable">
<TextView
android:id="@+id/description"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="#5d5d5d"
android:textStyle="bold"/>
<TextView
android:id="@+id/email"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="#5d5d40"
android:textStyle="bold" />
<TextView
android:id="@+id/telephone"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="#5d5d40"
android:textStyle="bold" />
</LinearLayout>
</LinearLayout>