我想使用aChartEngine绘制折线图。我正在从SQLite数据库中读取温度和时间。这些值正在存储并且也正在从DB中成功读取，但应显示图形的线性布局为空。善意的帮助。提前谢谢。
MainActivity.java
package com.database_trial;
import java.util.List;
import org.achartengine.ChartFactory;
import org.achartengine.GraphicalView;
import org.achartengine.chart.PointStyle;
import org.achartengine.model.TimeSeries;
import org.achartengine.model.XYMultipleSeriesDataset;
import org.achartengine.renderer.XYMultipleSeriesRenderer;
import org.achartengine.renderer.XYSeriesRenderer;
import trial.helper.DBHelper;
import trial.model.Temperature;
import android.os.Bundle;
import android.app.Activity;
import android.graphics.Color;
import android.util.Log;
import android.view.Menu;
import android.widget.LinearLayout;
public class MainActivity extends Activity {
DBHelper db;
private GraphicalView mChart;
//arrays for x and y axis of graph
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);// deleting old data
db = new DBHelper(getApplicationContext());
Log.d("ans1", "fyn here");
db.deleteTempReadings();
// inserting data to temp table
Log.i("insert", "Inserting Records...");
db.insertTemperature(new Temperature("12.35"));
db.insertTemperature(new Temperature("25.36"));
db.insertTemperature(new Temperature("35.34"));
// reading data from db
Log.i("Reading", "Reading Records...");
List<Temperature> temp = db.getAllTempReadings();
int arraySize=temp.size();
double tempArray[]=new double[arraySize];
int timeArray[]=new int [arraySize];
//Log.d("ans", String.valueOf(temp.size()));
for (Temperature t : temp) {
String log="SENSOR ID: "+t.getSensorId()+"TEMPERATURE: "+t.getTemperature()+"TIME: "+t.getTimestamp();
Log.d("Record"+t, log);
}
// Reading values into the array!
for(int i=0;i<arraySize;i++){
tempArray[i]=Double.parseDouble(temp.get(i).getTemperature());
timeArray[i]=Integer.parseInt(temp.get(i).getTimestamp());
System.out.println("i: "+ tempArray[i]+" ,"+timeArray[i]);
}
TimeSeries series=new TimeSeries("Line1");
for(int i=0;i<tempArray.length;i++){
series.add(tempArray[i],timeArray[i]);
}
XYMultipleSeriesDataset dataset=new XYMultipleSeriesDataset();
dataset.addSeries(series);
//properties of line
XYSeriesRenderer renderer =new XYSeriesRenderer();
renderer.setColor(Color.YELLOW);
renderer.setPointStyle(PointStyle.DIAMOND);
renderer.setFillPoints(true);
XYMultipleSeriesRenderer mRenderer=new XYMultipleSeriesRenderer();
mRenderer.addSeriesRenderer(renderer);
mRenderer.setBackgroundColor(Color.BLACK);
mRenderer.setChartTitle("TEMPERATURE LINE GRAPH");
mRenderer.setAxesColor(Color.YELLOW);
mRenderer.setApplyBackgroundColor(true);
mRenderer.setXTitle("TEMPERATURE");
mRenderer.setYTitle("TIME");
mRenderer.setZoomButtonsVisible(true);
for(int i=0;i<tempArray.length;i++)
{
mRenderer.addXTextLabel(i, " :temp");
}
LinearLayout chart_container=(LinearLayout)findViewById(R.id.lineGraph);
mChart = ChartFactory.getLineChartView(this, dataset,mRenderer);
if(mChart==null){
Log.i("mChart: ", "null");
}
else{
Log.i("mChart: ", "not null but not displaying graph");
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
/ * DBHelper.java * /
package trial.helper;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.Locale;
import trial.model.Temperature;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
public class DBHelper extends SQLiteOpenHelper {
private static final String DATABASE_NAME = "SensorDB";
private static final int DATABASE_VERSION = 1;
private static final String LOG = DBHelper.class.getName();
// TABLE NAMES
private static final String TEMPERATURE_TABLE = "temp_table";
// temperature class
private static final String KEY_SENSOR_ID = "sensor_id";
private static final String KEY_TEMPERATURE = "temperature";
private static final String KEY_TIMESTAMP = "timestamp";
String CREATE_TEMP_TABLE = "CREATE TABLE " + TEMPERATURE_TABLE + "("
+ KEY_SENSOR_ID + " TEXT ," + KEY_TEMPERATURE + " REAL, "
+ KEY_TIMESTAMP + " TEXT DEFAULT CURRENT_TIMESTAMP )";
public DBHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(CREATE_TEMP_TABLE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + TEMPERATURE_TABLE);
onCreate(db);
}
// CRUD OPERATIONS
// --TEMPERATURETABLE--//
// INSERT RECORD INTO TEMPERATURE TABLE
public void insertTemperature(Temperature temp) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
SimpleDateFormat dateFormat = new SimpleDateFormat(
"SSS", Locale.getDefault());
Date date = new Date();
values.put(KEY_SENSOR_ID, "MySensor");
values.put(KEY_TEMPERATURE, temp.getTemperature());
values.put(KEY_TIMESTAMP, dateFormat.format(date));
try
{
db.insert(TEMPERATURE_TABLE, null, values);
}catch(Exception ex){
Log.d("Exception in inserting data", ex.toString());
}finally{
db.close();
}
}
// READ ALL RECORDS
public List<Temperature> getAllTempReadings() {
List<Temperature> temp = new ArrayList<Temperature>();
SQLiteDatabase db = this.getReadableDatabase();
String selectQuery = "SELECT * FROM " + TEMPERATURE_TABLE;
Cursor c = db.rawQuery(selectQuery, null);
if (c.moveToFirst()) {
do {
Temperature t = new Temperature();
t.setSensorId(c.getString(0));
t.setTemperature(c.getString(1));
t.setTimestamp(c.getString(2));
temp.add(t);
} while (c.moveToNext());
}
return temp;
}
// DELETE All RECORDs
public void deleteTempReadings() {
SQLiteDatabase db = this.getWritableDatabase();
String selectQuery = "Delete from " + TEMPERATURE_TABLE;
db.execSQL(selectQuery);
Log.d(LOG, selectQuery);
}
}
/* **This is my model class for the database
Temperature.java** */
package trial.model;
import java.util.*;
import java.text.SimpleDateFormat;
import java.util.Locale;
public class Temperature {
String sensor_id;
String temperature;
String timestamp;
public Temperature() {
}
public Temperature(String temperature) {
this.temperature = temperature;
}
public Temperature(String sensor_id, String temperature, String timestamp) {
this.sensor_id = sensor_id;
this.temperature = temperature;
this.timestamp = timestamp;
}
// getters
public String getSensorId() {
return this.sensor_id;
}
public String getTemperature() {
return this.temperature;
}
public String getTimestamp() {
return this.timestamp;
}
// setters
public void setSensorId(String sensor_id) {
this.sensor_id = sensor_id;
}
public void setTemperature(String temperature) {
this.temperature = temperature;
}
public void setTimestamp(String timestamp) {
this.timestamp = timestamp;
}
}
// activity_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true"
android:layout_marginRight="110dp"
android:layout_marginTop="197dp"
android:orientation="vertical"
android:id="@+id/lineGraph">
</LinearLayout>
</RelativeLayout>
// logcat
04-21 06:48:19.974: D/dalvikvm(2386): Not late-enabling CheckJNI (already on)
04-21 06:48:21.545: D/ans1(2386): fyn here
04-21 06:48:21.833: D/trial.helper.DBHelper(2386): Delete from temp_table
04-21 06:48:21.864: I/insert(2386): Inserting Records...
04-21 06:48:22.023: I/Reading(2386): Reading Records...
04-21 06:48:22.054: D/Recordtrial.model.Temperature@41730cf8(2386): SENSOR ID: MySensor TEMPERATURE: 12.35 TIME: 967
04-21 06:48:22.054: D/Recordtrial.model.Temperature@41730e70(2386): SENSOR ID: MySensor TEMPERATURE: 25.36 TIME: 994
04-21 06:48:22.054: D/Recordtrial.model.Temperature@41730f50(2386): SENSOR ID: MySensor TEMPERATURE: 35.34 TIME: 022
04-21 06:48:22.063: I/System.out(2386): i: 12.35 ,967
04-21 06:48:22.063: I/System.out(2386): i: 25.36 ,994
04-21 06:48:22.063: I/System.out(2386): i: 35.34 ,22
04-21 06:48:22.554: D/dalvikvm(2386): GC_FOR_ALLOC freed 207K, 12% free 2810K/3176K, paused 39ms, total 45ms
04-21 06:48:22.623: I/mChart:(2386): not null but not displaying graph
04-21 06:48:22.943: D/gralloc_goldfish(2386): Emulator without GPU emulation detected.
04-21 06:48:23.053: I/ActivityManager(374): Displayed com.database_trial/.MainActivity: +3s220ms
答案 0 :(得分：0)
查看此链接访问http://androidforbegineers.blogspot.in/2013/07/bar-chart-in-android-using-achartengine.html如果您未在Android清单中添加此行，请将其添加为活动
活动android：name =＆＃34; org.achartengine.GraphicalActivity＆＃34;
如果在主活动中添加一个按钮来生成图形（这是上面链接中遵循的方法），也会使用捆绑方法将数据从数据库传递到图表生成类（{{3} }）