我有一个自定义 list_item，它所在的 ListView 有一个转到新 Activity 的 onItemClickListener。我面临的问题是 onItemClickListener 由于无法识别所单击项目的 ID 而没有响应。我怀疑这个问题源于我的 CustomAdapter 但我不确定可以采取什么措施来解决它。记录的 ID 列出为:
D/ListDataActivity: onItemClick: You Clicked on android.database.sqlite.SQLiteCursor@22fda4b
ListDataActivity.java:
public class ListDataActivity extends AppCompatActivity {
private static final String TAG = "ListDataActivity";
DatabaseHelper mDatabaseHelper;
TextView mTaskName;
TextView mTaskDesc;
ArrayAdapter adapter;
CustomAdapter customAdapter;
private ListView mListView;
DatabaseHelper db = new DatabaseHelper(this);
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.list_layout);
mListView = (ListView) findViewById(R.id.listView);
mDatabaseHelper = new DatabaseHelper(this);
mTaskDesc = (TextView) findViewById(R.id.task_desc);
mTaskName = (TextView) findViewById(R.id.task_name);
populateListView();
}
private void populateListView() {
String[] fromColumns = mDatabaseHelper.databaseToStringArray();
int[] toViews = new int[]{R.id.task_name, R.id.task_desc};
Cursor cursor;
cursor = mDatabaseHelper.getWritableDatabase().rawQuery(" SELECT * FROM " + mDatabaseHelper.TABLE_NAME + " WHERE 1 ", null);
Log.d(TAG, "populateListView: Displaying data in the ListView.");
SimpleCursorAdapter customAdapter = new CustomAdapter(this, R.layout.list_item, cursor, fromColumns, toViews,0);
mListView.setAdapter(customAdapter);
mListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
String name = adapterView.getItemAtPosition(i).toString();
Log.d(TAG, "onItemClick: You Clicked on " + name);
Cursor data = mDatabaseHelper.getItemID(name);
int priority = 10;
int itemID = -1;
while(data.moveToNext()){
itemID = data.getInt(0);
}
if(itemID > -1){
Log.d(TAG, "onItemClick: The ID is: " + itemID);
Intent editScreenIntent = new Intent(ListDataActivity.this, EditDataActivity.class);
editScreenIntent.putExtra("id",itemID);
editScreenIntent.putExtra("name",name);
editScreenIntent.putExtra("priority",priority);
startActivity(editScreenIntent);
}
else{
toastMessage("No ID associated with that name");
}
}
});
}
private void toastMessage(String message){
Toast.makeText(this,message, Toast.LENGTH_SHORT).show();
}
}
自定义适配器.java:
public class CustomAdapter extends SimpleCursorAdapter {
private int layout;
private Context context;
private DatabaseHelper mDatabaseHelper;
public CustomAdapter(Context context, int layout, Cursor c, String[] from, int[] to, int flags) {
super(context, layout, c, from, to, flags);
this.layout = layout;
this.context = context;
}
@Override
public View newView(Context context, Cursor cursor, ViewGroup parent) {
Cursor c = getCursor();
final LayoutInflater inflater = LayoutInflater.from(context);
View v = inflater.inflate(R.layout.list_item, parent, false);
bindView(v, context, c);
return v;
}
@Override
public void bindView(View v, Context context, Cursor c) {
int taskNameColumn = c.getColumnIndex(mDatabaseHelper.COL2);
int taskDescColumn = c.getColumnIndex(mDatabaseHelper.COL4);
String mTaskName = c.getString(taskNameColumn);
String mTaskDesc = c.getString(taskDescColumn);
TextView taskName = (TextView) v.findViewById(R.id.task_name);
if (taskName != null){
taskName.setText(mTaskName);
}
TextView taskDesc = (TextView) v.findViewById(R.id.task_desc);
if (taskDesc != null){
taskDesc.setText(mTaskDesc);
}
}
}
这是我的 list_item.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:background="@color/colorWhite">
<TextView
android:id="@+id/task_name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:layout_marginStart="55dp"
android:layout_marginTop="25dp"
android:text="TextView" />
<View
android:id="@+id/viewbutton"
android:layout_width="16dp"
android:layout_height="16dp"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:layout_marginStart="21dp"
android:layout_marginTop="24dp"
android:background="@layout/round" />
<TextView
android:id="@+id/task_desc"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/task_name"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:layout_marginStart="55dp"
android:layout_marginTop="53dp"
android:layout_marginBottom="10dp"
android:focusable="false"
android:text="Undefined"
android:textStyle="bold" />
</RelativeLayout>
如果您希望我详细说明其中任何内容，我将很乐意。提前致谢!
最佳答案
当您使用 CursorAdapter 时，l(传递给覆盖的 onItemClick 方法的第四个参数)将是 id。这假设 _id 列是 rowid 的别名(即您有 _id INTEGER PRIMARY KEY 编码，有或没有 AUTOINCREMENT )。
- 注意第四个参数'l'，对于其他适配器(例如ArrayAdapter)将不是id 相反，它通常是位置(长整型)，因此与第三个参数相同。
因此尝试Log.d(TAG, "onItemClick: You Clicked on " + name + " with an id of " + String.valueOf(l));
名称显示为android.database.sqlite.SQLiteCursor@22fda4b因为由 getItem 检索的底层项是 Cursor，而它的 toString 方法将是打印对象引用的默认继承方法。
你可能想要这样的东西:-
mListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
Intent editScreenIntent = new Intent(ListDataActivity.this, EditDataActivity.class);
editScreenIntent.putExtra("id",l); //<<<<<<<<<< THE ID AS kindly supplied by the CursorAdapter
editScreenIntent.putExtra("name",data.getString(data.getColumnIndex(mDatabaseHelper.COL2)));
editScreenIntent.putExtra("priority",data.getColumnIndex(mDatabaseHelper.COL4));
startActivity(editScreenIntent);
}
}
});
- 但是，您可以轻松(并且可以说更正确)通过意图传递 ID，然后从调用的 Activity 中的表中检索数据(名称和优先级)。
- 请注意，上述代码是原则代码，尚未经过测试，因此可能包含错误。
- 光标应位于当前行/相应行，因此需要进行任何移动。
关于java - ListItem.onItemClickListener 与 CustomAdapter 无响应，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/52882972/