我正在尝试将数据从sqlLite数据库填充到列表视图中。
以下是我尝试使用cursoradapter将数据提取到listview中的代码。
public class TransactionActivity extends AppCompatActivity {
DBOperations dbOperations;
ListView lv;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_transaction);
lv=(ListView)findViewById(R.id.listView);
dbOperations=new DBOperations(TransactionActivity.this);
Cursor tablecursor = dbOperations.getTableRecords(DBOperations.TABLE_TRANSACTIONS);
Myadapter sca = new Myadapter(TransactionActivity.this,tablecursor,true);
lv.setAdapter(sca);
}
public class Myadapter extends CursorAdapter{
public Myadapter(Context context,Cursor tablecursor, boolean autoRequery){
super(context,tablecursor,autoRequery);}
@Override
public View newView(Context context, Cursor tablecursor, ViewGroup viewGroup) {
LayoutInflater inflater = (LayoutInflater) context.getSystemService(LAYOUT_INFLATER_SERVICE);
View view = inflater.inflate(R.layout.listitem, viewGroup, false);
return view;
}
@Override
public void bindView(View view, Context context, Cursor cursor) {
cursor.moveToFirst();
TextView Accnameview = (TextView)findViewById(R.id.textView);
TextView Incomevalueview=(TextView)findViewById(R.id.textView2);
String accname = cursor.getString(cursor.getColumnIndex(DBOperations.COL_ACC_NAME));
String incomev =cursor.getString(cursor.getColumnIndex(DBOperations.COL_DEBIT));
Accnameview.setText(accname);
Incomevalueview.setText(incomev);
}
}
}
夸大的listview.xml是
<?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="100dp"
android:background="@android:color/darker_gray">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="Large Text"
android:id="@+id/textView" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceMedium"
android:text="Medium Text"
android:id="@+id/textView2"
android:layout_gravity="right" />
尝试这样做时,我收到以下错误。
09-21 09:13:04.715 10142-10142 / com.example.joshigir.finance D / OpenGLRenderer:启用调试模式0 09-21 09:13:45.007 10142-10142 / com.example.joshigir.finance W / EGL_genymotion: eglSurfaceAttrib未实施09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance D / AndroidRuntime:正在关闭 VM 09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance W / dalvikvm:threadid = 1:线程退出未捕获的异常 (组= 0xa4c96b20)09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance E / AndroidRuntime:致命 例外:主要09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance E / AndroidRuntime:流程: com.example.joshigir.finance,PID:10142 09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance E / AndroidRuntime: java.lang.NullPointerException 09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance E / AndroidRuntime:at com.example.joshigir.finance.TransactionActivity $ Myadapter.bindView(TransactionActivity.java:69) 09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance E / AndroidRuntime:at android.widget.CursorAdapter.getView(CursorAdapter.java:254)09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance E / AndroidRuntime:at android.widget.AbsListView.obtainView(AbsListView.java:2255)09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance E / AndroidRuntime:at android.widget.ListView.measureHeightOfChildren(ListView.java:1263) 09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance E / AndroidRuntime:at android.widget.ListView.onMeasure(ListView.java:1175)09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance E / AndroidRuntime:在android.view.View.measure(View.java:16497) 09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance E / AndroidRuntime:at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:719) 09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance E / AndroidRuntime:at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:455)09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance E / AndroidRuntime:在android.view.View.measure(View.java:16497) 09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance E / AndroidRuntime:at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125) 09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance E / AndroidRuntime:at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance E / AndroidRuntime:at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:135) 09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance E / AndroidRuntime:在android.view.View.measure(View.java:16497) 09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance E / AndroidRuntime:at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125) 09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance E / AndroidRuntime:at android.support.v7.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:391) 09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance E / AndroidRuntime:在android.view.View.measure(View.java:16497) 09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance E / AndroidRuntime:at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125) 09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance E / AndroidRuntime:at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance E / AndroidRuntime:在android.view.View.measure(View.java:16497) 09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance E / AndroidRuntime:at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125) 09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance E / AndroidRuntime:at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404) 09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance E / AndroidRuntime:at android.widget.LinearLayout.measureVertical(LinearLayout.java:695) 09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance E / AndroidRuntime:at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance E / AndroidRuntime:在android.view.View.measure(View.java:16497) 09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance E / AndroidRuntime:at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125) 09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance E / AndroidRuntime:at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance E / AndroidRuntime:at com.android.internal.policy.impl.PhoneWindow $ DecorView.onMeasure(PhoneWindow.java:2291) 09-21 09:13:46.507 10142-10142 / com.example.joshigir.finance E / AndroidRuntime:在android.view.View.measure(View.java:16497)
请帮助找出错误。
答案 0 :(得分:1)
来自bindView(View, Context, Cursor)
班级的Myadapter
方法:
TextView Accnameview = (TextView)findViewById(R.id.textView);
TextView Incomevalueview=(TextView)findViewById(R.id.textView2);
您需要在方法的findViewById(int)
属性上调用view
,如下所示:
TextView Accnameview = (TextView) view.findViewById(R.id.textView);
TextView Incomevalueview = (TextView) view.findViewById(R.id.textView2);
否则,您正在使用findViewById(int)
封闭类中的TransactionActivity
方法,该类在“活动”视图层次结构中查找TextView。由于适配器的视图尚未附加到Activity视图,因此它找不到它们并返回null。因此,您在setText(String)
方法结束时在null TextView上调用bindView(View, Context, Cursor)
。
有关CursorAdapter示例,请参阅here。
答案 1 :(得分:0)
@Override
public void bindView(View view, Context context, Cursor cursor) {
// don't call this here; the cursor is already positioned on the
// the correct record when this method is called
// cursor.moveToFirst();
// you need to call findViewById on the view parameter
// TextView Accnameview = (TextView)findViewById(R.id.textView);
// TextView Incomevalueview=(TextView)findViewById(R.id.textView2);
TextView Accnameview = (TextView) view.findViewById(R.id.textView);
TextView Incomevalueview=(TextView) view.findViewById(R.id.textView2);
String accname = cursor.getString(cursor.getColumnIndex(DBOperations.COL_ACC_NAME));
String incomev =cursor.getString(cursor.getColumnIndex(DBOperations.COL_DEBIT));
Accnameview.setText(accname);
Incomevalueview.setText(incomev);
}