执行上的SQLite Db的查询时,现在我在这里获得空指针异常。在,ViewAllData方法myAdapter = new SQLCustomViewAllDataAdapter(SQLViewAllData.this,aList);
这里我越来越错误创建构造函数。NullPointerException异常android系统
SQLViewAllData.java
public class SQLViewAllData extends Activity {
private SQLDbHelper myDbHelper;
private SQLCustomViewAllDataAdapter myAdapter;
private ListView myListView;
private ArrayList<SQLPojo.UserDetails> aList = new ArrayList<>();
//private Context myContext;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.listview_view_data);
//myContext = this;
widgetInitialization();
viewAllData();
}
//Initializing Widgets
public void widgetInitialization() {
myDbHelper = new SQLDbHelper(this);
myListView = (ListView)findViewById(R.id.listview_view_data_LV);
}
public ArrayList<SQLPojo.UserDetails> getUserInfo(){
return myDbHelper.getUserDetails();
}
//view all data stored in DB
public void viewAllData() {
aList = getUserInfo();
myAdapter = new SQLCustomViewAllDataAdapter(SQLViewAllData.this,aList);
myListView.setAdapter(myAdapter);
}
}
尝试'myDbHelper = new SQLDbHelper(SQLViewAllData.this);' –
为什么你要复制问题:http://stackoverflow.com/questions/41306863/how-to-get-sqlite-db-values-in-arraylist -to-listview? – pskink
这里有一个链接解释了哪些关于不同的上下文以及它们的用法。 https://possiblemobile.com/2013/06/context – muthuraj