I am having trouble trying get a graph working in my app but I don't know where i'm going wrong with this code. The code builds but crashes selecting the activity. I think I may have structured it incorrectly as I may be trying create a graph before I obtain data from the database. If anyone can point out my mistake, I would be grateful.
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_graph);
myDB = new DatabaseCode(this);
SQLiteDatabase db = myDB.getWritableDatabase();
Cursor cursor=db.rawQuery("select * from "+TABLE_NAME,null);
if(cursor.getCount()==0){
return;
}
else {
ArrayList<Integer> ListArray = new ArrayList<Integer>();
//
while (cursor.moveToNext()) {
ListArray.add(cursor.getInt(cursor.getColumnIndex("COL_2")));
}
GraphView graph = (GraphView) findViewById(R.id.graph);
LineGraphSeries<DataPoint> series = new LineGraphSeries<DataPoint>(new DataPoint[] {
new DataPoint(0,ListArray.get(0)),
new DataPoint(1,ListArray.get(1)),
new DataPoint(2,ListArray.get(2))
});
graph.addSeries(series);
}
}
}
Here is the error log.
04-30 16:34:18.912 20125-20125/com.example.fitmess.project E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.fitmess.project, PID: 20125
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.fitmess.project/com.example.fitmess.project.GraphActivity}: java.lang.IllegalStateException: Couldn't read row 0, col -1 from CursorWindow. Make sure the Cursor is initialized correctly before accessing data from it.
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3319)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3415)
at android.app.ActivityThread.access$1100(ActivityThread.java:229)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1821)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:7331)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)
Caused by: java.lang.IllegalStateException: Couldn't read row 0, col -1 from CursorWindow. Make sure the Cursor is initialized correctly before accessing data from it.
at android.database.CursorWindow.nativeGetLong(Native Method)
at android.database.CursorWindow.getLong(CursorWindow.java:524)
at android.database.CursorWindow.getInt(CursorWindow.java:591)
at android.database.AbstractWindowedCursor.getInt(AbstractWindowedCursor.java:69)
at com.example.fitmess.project.GraphActivity.onCreate(GraphActivity.java:36)
at android.app.Activity.performCreate(Activity.java:6904)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1136)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3266)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3415)
at android.app.ActivityThread.access$1100(ActivityThread.java:229)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1821)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:7331)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)
while accessing data from cursor you have to check data in cursor and move cursor to first location and the looping will be done like below example
if(cursor.moveToFirst()) //this will move cursor to first position
{
do{
//your code to fetch data from cursor
ListArray.add(cursor.getInt(cursor.getColumnIndex("COL_2")));
}while(cursor.moveToNext());
}
also check the "COL_2" column name is right one as per schema.