我有一个蓝牙应用程序，可以绘制来自加速度计的数据，如果工作正常，但是在运行约2分钟后，出现以下错误，应用程序关闭。我正在使用graphview绘制数据和选项卡的图形以分别显示它们。下面显示的应用程序代码来自制图活动。
编辑：我知道什么是空指针异常。我不知道的是它的来源。这就是我需要的帮助，因为我认为这不是我写的。
2019-03-11 10:01:07.385 15431-15431/com.example.tabbedgraph I/Choreographer: Skipped 76 frames! The application may be doing too much work on its main thread.
2019-03-11 10:01:07.386 15431-17408/com.example.tabbedgraph D/X Series Try: Success
2019-03-11 10:01:07.469 15431-17409/com.example.tabbedgraph D/Data mani. X: DataVal: X: -0.04
2019-03-11 10:01:07.469 15431-17409/com.example.tabbedgraph D/Data mani. Y: DataVal: Y: -2.82
2019-03-11 10:01:07.469 15431-17409/com.example.tabbedgraph D/Data mani. Z: DataVal: Z: 7.22
2019-03-11 10:01:07.475 15431-17409/com.example.tabbedgraph D/Y Series Try: Success
2019-03-11 10:01:07.480 15431-15431/com.example.tabbedgraph D/AndroidRuntime: Shutting down VM
2019-03-11 10:01:07.489 15431-15431/com.example.tabbedgraph E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.tabbedgraph, PID: 15431
java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.Integer.intValue()' on a null object reference
at com.jjoe64.graphview.GridLabelRenderer.drawVerticalSteps(GridLabelRenderer.java:1348)
at com.jjoe64.graphview.GridLabelRenderer.draw(GridLabelRenderer.java:1117)
at com.jjoe64.graphview.GraphView.drawGraphElements(GraphView.java:307)
at com.jjoe64.graphview.GridLabelRenderer.draw(GridLabelRenderer.java:1108)
at com.jjoe64.graphview.GraphView.drawGraphElements(GraphView.java:307)
at com.jjoe64.graphview.GraphView.onDraw(GraphView.java:336)
at android.view.View.draw(View.java:20370)
at android.view.View.updateDisplayListIfDirty(View.java:19315)
at android.view.View.draw(View.java:20093)
at android.view.ViewGroup.drawChild(ViewGroup.java:4421)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4207)
at android.view.View.updateDisplayListIfDirty(View.java:19306)
at android.view.View.draw(View.java:20093)
at android.view.ViewGroup.drawChild(ViewGroup.java:4421)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4207)
at android.view.View.updateDisplayListIfDirty(View.java:19306)
at android.view.View.draw(View.java:20093)
at android.view.ViewGroup.drawChild(ViewGroup.java:4421)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4207)
at android.view.View.updateDisplayListIfDirty(View.java:19306)
at android.view.View.draw(View.java:20093)
at android.view.ViewGroup.drawChild(ViewGroup.java:4421)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4207)
at android.view.View.updateDisplayListIfDirty(View.java:19306)
at android.view.View.draw(View.java:20093)
at android.view.ViewGroup.drawChild(ViewGroup.java:4421)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4207)
at android.view.View.updateDisplayListIfDirty(View.java:19306)
at android.view.View.draw(View.java:20093)
at android.view.ViewGroup.drawChild(ViewGroup.java:4421)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4207)
at android.support.constraint.ConstraintLayout.dispatchDraw(ConstraintLayout.java:2023)
at android.view.View.updateDisplayListIfDirty(View.java:19306)
at android.view.View.draw(View.java:20093)
at android.view.ViewGroup.drawChild(ViewGroup.java:4421)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4207)
at android.view.View.updateDisplayListIfDirty(View.java:19306)
at android.view.View.draw(View.java:20093)
at android.view.ViewGroup.drawChild(ViewGroup.java:4421)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4207)
at android.view.View.updateDisplayListIfDirty(View.java:19306)
at android.view.View.draw(View.java:20093)
at android.view.ViewGroup.drawChild(ViewGroup.java:4421)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:4207)
at android.view.View.draw(View.java:20373)
at com.android.internal.policy.DecorView.draw(DecorView.java:980)
at android.view.View.updateDisplayListIfDirty(View.java:19315)
at android.view.ThreadedRenderer.updateViewTreeDisplayList(ThreadedRenderer.java:686)
at android.view.ThreadedRenderer.updateRootDisplayList(ThreadedRenderer.java:692)
at android.view.ThreadedRenderer.draw(ThreadedRenderer.java:800)
at android.view.ViewRootImpl.draw(ViewRootImpl.java:3496)
at android.view.ViewRootImpl.performDraw(ViewRootImpl.java:3283)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2818)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1780)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:7827)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:911)
at android.view.Choreographer.doCallbacks(Choreographer.java:723)
at android.view.Choreographer.doFrame(Choreographer.java:658)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:897)
at android.os.Handler.handleCallback(Handler.java:789)
at android.os.Handler.dispatchMessage(Handler.java:98)
at android.os.Looper.loop(Looper.java:164)
2019-03-11 10:01:07.490 15431-15431/com.example.tabbedgraph E/AndroidRuntime: at android.app.ActivityThread.main(ActivityThread.java:6944)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:327)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1374)
2019-03-11 10:01:07.562 15431-15473/com.example.tabbedgraph I/onCharacteristicChanged: Entered
2019-03-11 10:01:07.563 15431-15473/com.example.tabbedgraph I/Message: Z: 7.26
2019-03-11 10:01:07.563 15431-15473/com.example.tabbedgraph D/Bluetooth Device: Data sent to show data
2019-03-11 10:01:07.563 15431-15473/com.example.tabbedgraph I/onCharacteristicChanged: Bye
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public class ShowData extends Activity {
private String SHOWDATA = "Graph Activity";
TextView Xval;
TextView Yval;
TextView Zval;
TabHost host;
int X_DATA_TAB = 0;
int Y_DATA_TAB = 1;
int Z_DATA_TAB = 2;
final LineGraphSeries<DataPoint> xSeries = new LineGraphSeries<>();
final LineGraphSeries<DataPoint> ySeries = new LineGraphSeries<>();
final LineGraphSeries<DataPoint> zSeries = new LineGraphSeries<>();
// LocalBroadcastManager lbm = LocalBroadcastManager.getInstance(this);
LocalBroadcastManager lbm;
int whereX, whereY, whereZ;
GraphView graph1, graph2, graph3;
Handler graphHandle = new Handler();
long start = System.currentTimeMillis();
// LocalBroadcastManager lbm = LocalBroadcastManager.getInstance(this);
IntentFilter incomingData = new IntentFilter("Data Reception");
ArrayList pointsArray = new ArrayList();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_show_data);
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_SENSOR_LANDSCAPE);
lbm = LocalBroadcastManager.getInstance(this);
Log.i(SHOWDATA, "onCreate entered");
Xval = findViewById(R.id.valueX);
Xval.setTextColor(Color.RED);
Yval = findViewById(R.id.valueY);
Yval.setTextColor(Color.GREEN);
Zval = findViewById(R.id.valueZ);
Zval.setTextColor(Color.BLUE);
graph1 = (GraphView) findViewById(R.id.graphX);
graph1.getGridLabelRenderer().setHorizontalAxisTitle("time (s)");
graph1.getGridLabelRenderer().setVerticalAxisTitle("Accel. (m*s^-2)");
graph2 = (GraphView) findViewById(R.id.graphY);
graph2.getGridLabelRenderer().setHorizontalAxisTitle("time (s)");
graph2.getGridLabelRenderer().setVerticalAxisTitle("Accel. (m*s^-2)");
graph3 = (GraphView) findViewById(R.id.graphZ);
graph3.getGridLabelRenderer().setHorizontalAxisTitle("time (s)");
graph3.getGridLabelRenderer().setVerticalAxisTitle("Accel. (m*s^-2)");
//LocalBroadcastManager lbm = LocalBroadcastManager.getInstance(this);
xSeries.setColor(Color.RED);
ySeries.setColor(Color.GREEN);
zSeries.setColor(Color.BLUE);
Viewport vp1 = graph1.getViewport();
vp1.setXAxisBoundsManual(true);
vp1.setMinX(0);
vp1.setMaxX(10);
Viewport vp2 = graph2.getViewport();
vp2.setXAxisBoundsManual(true);
vp2.setMinX(0);
vp2.setMaxX(10);
Viewport vp3 = graph3.getViewport();
vp3.setXAxisBoundsManual(true);
vp3.setMinX(0);
vp3.setMaxX(10);
// lbm.registerReceiver(xyzData, incomingData);
host = findViewById(R.id.tabhost);
LocalActivityManager mLocalActivityManager = new LocalActivityManager(ShowData.this, false);
mLocalActivityManager.dispatchCreate(savedInstanceState);
host.setup(mLocalActivityManager);
TabHost.TabSpec spec = host.newTabSpec("X tab");
spec.setContent(R.id.Xgraph);
spec.setIndicator("X tab");
host.addTab(spec);
spec = host.newTabSpec("Y tab");
spec.setContent(R.id.Ygraph);
spec.setIndicator("Y tab");
host.addTab(spec);
spec = host.newTabSpec("Z tab");
spec.setContent(R.id.tab3);
spec.setIndicator("Z tab");
host.addTab(spec);
host.setCurrentTab(0);
}
public BroadcastReceiver xyzData = new BroadcastReceiver() {
@Override
public void onReceive(Context context, final Intent intent) {
//Do the things
final String Xdata = intent.getStringExtra("X data");
final String Ydata = intent.getStringExtra("Y data");
final String Zdata = intent.getStringExtra("Z data");
Xval.setText(Xdata);
Yval.setText(Ydata);
Zval.setText(Zdata);
Thread graphRelated = new Thread(new Runnable() {
@Override
public void run() {
String Xdata2 = null;
String Ydata2 = null;
String Zdata2 = null;
try {
if (Xdata.contains("X")) {
whereX = Xdata.indexOf("X");
try {
Xdata2 = Xdata.substring(whereX + 3, whereX + 8);
Log.d("Data mani. X", "DataVal: " + Xdata);
} catch (Exception e) {
Log.d("X at end", "" + whereX);
}
}
} catch(Exception e){
e.printStackTrace();
}
try {
if (Ydata.contains("Y")) {
whereY = Ydata.indexOf("Y");
try {
Ydata2 = Ydata.substring(whereY + 3, whereY + 8);
Log.d("Data mani. Y", "DataVal: " + Ydata);
} catch (Exception e) {
Log.d("Y at end", "" + whereY);
}
}
} catch(Exception e){
e.printStackTrace();
}
try {
if (Zdata.contains("Z")) {
whereZ = Zdata.indexOf("Z");
try {
Zdata2 = Zdata.substring(whereZ + 3, whereZ + 8);
Log.d("Data mani. Z", "DataVal: " + Zdata);
} catch (Exception e) {
Log.d("Z at end", "" + whereZ);
}
}
} catch(Exception e){
e.printStackTrace();
}
if (host.getCurrentTab() == X_DATA_TAB){
try{
addEntry(Xdata2, xSeries);
graph1.addSeries(xSeries);
Log.d("X Series Try", "Success");
}catch (Exception e){
e.printStackTrace();
}
}
if (host.getCurrentTab() == Y_DATA_TAB){
try{
addEntry(Ydata2, ySeries);
graph2.addSeries(ySeries);
Log.d("Y Series Try", "Success");
}catch (Exception e){
e.printStackTrace();
}
}
if (host.getCurrentTab() == Z_DATA_TAB){
try{
addEntry(Zdata2, zSeries);
graph3.addSeries(zSeries);
Log.d("Z Series Try", "Success");
}catch (Exception e){
e.printStackTrace();
}
}
}
});
graphRelated.start();
}
};
public void addEntry(final String data, final LineGraphSeries Series){
// does there need to be a runnable in a function or can we just do one?
graphHandle.postDelayed(new Runnable() {
@Override
public void run() {
float dataVal = 0;
DataPoint point;
float current = (float) ((System.currentTimeMillis() - start)/1000.00);
Log.d("Time: ", "" + current);
try {
dataVal = Float.parseFloat(data);
point = new DataPoint(current ,dataVal);
Series.appendData(point, true, 50); // Data point, scroll to end, max data points
//lastX = lastX + 1;
Log.i("Time", "" + current);
Log.d("Add Entry", "" + Series.toString());
Log.d("dataVal1", "" + dataVal);
Log.i("Datapoint1", "Point " + point.toString());
point = null;
} catch (Exception e) {
e.printStackTrace();
Log.d("STR -> INT", "int dataVal contained string");
Log.d("dataVal2", "" + dataVal);
point = null;
}
}
}, 200);
}
@Override
public void onPause(){
super.onPause();
lbm.unregisterReceiver(xyzData);
}
@Override
public void onResume(){
super.onResume();
//LocalBroadcastManager lbm = LocalBroadcastManager.getInstance(this);
lbm.registerReceiver(xyzData, incomingData);
}
}