问题
Hi I am new to android and I am writing the following code to draw a bar graph taking the values from the database.
I have created the database using sqlite data browser. My problem is that when I execute the program the graph doesnot plot.
Thanks for your help in advance.
public class ChartActivity extends Activity {
private String productName;
private Context Jayant;
private Integer seriesCount;
public Intent execute(Context context) throws IOException {
SharedPreferences myPrefs = context.getSharedPreferences("myPrefs",
MODE_PRIVATE);
productName = myPrefs.getString("prodName", "nothing");
Jayant = context;
DatabaseAdapter dbA = new DatabaseAdapter(Jayant);
dbA.opendatabase();
seriesCount = dbA.getValues(productName).getCount();
dbA.close();
XYMultipleSeriesRenderer renderer = buildBarRender();
setChartSettings(renderer);
return ChartFactory.getBarChartIntent(context, getDateDemoDataset(),
renderer, Type.DEFAULT);
}
protected XYMultipleSeriesRenderer buildBarRender() {
XYMultipleSeriesRenderer renderer = new XYMultipleSeriesRenderer();
int[] colors = new int[] { Color.BLUE, Color.DKGRAY, Color.GREEN,
Color.RED, Color.CYAN, };
SimpleSeriesRenderer ssR = new SimpleSeriesRenderer();
for (int i = 0; i < seriesCount; i++) {
ssR = new SimpleSeriesRenderer();
ssR.setDisplayChartValues(true);
ssR.setChartValuesTextSize(30);
ssR.setColor(colors[i]);
renderer.addSeriesRenderer(ssR);
}
return renderer;
}
private XYMultipleSeriesDataset getDateDemoDataset() throws IOException {
XYMultipleSeriesDataset dataset = new XYMultipleSeriesDataset();
DatabaseAdapter dbA = new DatabaseAdapter(Jayant);
dbA.opendatabase();
Cursor Data = dbA.getValues(productName);
seriesCount = Data.getCount();
for (Data.move(-1); Data.moveToNext(); Data.isAfterLast()) {
CategorySeries series = new CategorySeries((Data.getString(Data
.getColumnIndex("Primary1"))));
series.add(Data.getInt(Data.getColumnIndex("Primary2")));
dataset.addSeries(series.toXYSeries());
}
Data.close();
dbA.close();
return dataset;
}
private void setChartSettings(XYMultipleSeriesRenderer renderer) throws IOException {
renderer.setAxisTitleTextSize(16);
renderer.setChartTitleTextSize(20);
renderer.setLabelsTextSize(15);
renderer.setLegendTextSize(15);
renderer.setMargins(new int[] { 20, 30, 15, 0 });
renderer.setChartTitle("Top 10 Travel Destinations");
renderer.setXTitle("Destinations");
renderer.setYTitle("Top 10");
renderer.setXAxisMin(0);
renderer.setXAxisMax(10.5);
renderer.setBarSpacing(0.0);
renderer.setYAxisMin(0);
renderer.setYAxisMax(maxValue());
}
private Double maxValue() throws IOException {
Double mValue = null;
DatabaseAdapter dbA = new DatabaseAdapter(Jayant);
dbA.opendatabase();
Cursor mV = dbA.getMaxValue(productName);
if (mV.moveToFirst())
mValue = mV.getInt(mV.getColumnIndex("Primary2")) * 1.1;
mV.close();
dbA.close();
return mValue;
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_chart);
}
}
DatabaseAdapter class to get the data from the database stored in the assets folder.
public class DatabaseAdapter extends SQLiteOpenHelper{
private Context mycontext;
private String DB_PATH = mycontext.getApplicationContext().getPackageName()+"Jayant";
private static String DB_NAME = "Jayant.sqlite";//the extension may be .sqlite or .db
public SQLiteDatabase myDataBase;
public DatabaseAdapter(Context context) throws IOException {
super(context,DB_NAME,null,1);
this.mycontext=context;
boolean dbexist = checkdatabase();
if (dbexist) {
opendatabase();
} else {
System.out.println("Database doesn't exist");
createdatabase();
}
}
public void createdatabase() throws IOException {
boolean dbexist = checkdatabase();
if(dbexist) {
} else {
this.getReadableDatabase();
try {
copydatabase();
} catch(IOException e) {
throw new Error("Error copying database");
}
}
}
private boolean checkdatabase() {
//SQLiteDatabase checkdb = null;
boolean checkdb = false;
try {
String myPath = DB_PATH + DB_NAME;
File dbfile = new File(myPath);
//checkdb = SQLiteDatabase.openDatabase(myPath,null,SQLiteDatabase.OPEN_READWRITE);
checkdb = dbfile.exists();
} catch(SQLiteException e) {
System.out.println("Database doesn't exist");
}
return checkdb;
}
private void copydatabase() throws IOException {
//Open your local db as the input stream
InputStream myinput = mycontext.getAssets().open(DB_NAME);
// Path to the just created empty db
@SuppressWarnings("unused")
String outfilename = DB_PATH + DB_NAME;
//Open the empty db as the output stream
OutputStream myoutput = new FileOutputStream("/data/data/flu.solutions.travelsense/databases /Jayant.sqlite");
// transfer byte to inputfile to outputfile
byte[] buffer = new byte[1024];
int length;
while ((length = myinput.read(buffer))>0) {
myoutput.write(buffer,0,length);
}
//Close the streams
myoutput.flush();
myoutput.close();
myinput.close();
}
public void opendatabase() throws SQLException {
//Open the database
String mypath = DB_PATH + DB_NAME;
myDataBase = SQLiteDatabase.openDatabase(mypath, null, SQLiteDatabase.OPEN_READWRITE);
}
public synchronized void close() {
if(myDataBase != null) {
myDataBase.close();
}
super.close();
}
@Override
public void onCreate(SQLiteDatabase arg0) {
// TODO Auto-generated method stub
}
@Override
public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
// TODO Auto-generated method stub
}
public Cursor getValues(String productName) {
// TODO Auto-generated method stub
return null;
}
public Cursor getMaxValue(String productName) {
// TODO Auto-generated method stub
return null;
}
}
回答1:
You are creating a graph, which looks like it should (as far as I know). But I cannot find the place where you add the graph to the view. Shouldn't there be some kind findViewById where you add the created graph to the view. Or at least say to Android that it should draw the chart on the view somewhere, but even that I cannot find.
I don't have a lot of experience with creating charts in Android though.
来源：https://stackoverflow.com/questions/13909297/graph-plotted-using-database-doesnt-plot-in-android