为什么我无法在Toast中看到我的数据？每次我运行应用程序，它都会崩溃。但如果我删除Toast它会顺利运行。
到目前为止，这是我的代码，我删除了所有不相关的代码
GoogleMaps Class.
public class GoogleMaps extends MapActivity implements LocationListener {
public void addLocation() {
AlertDialog.Builder alert = new AlertDialog.Builder(this);
final EditText input = new EditText(this);
alert.setTitle("What do you want to call the location?");
alert.setView(input);
alert.setPositiveButton("Ok", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
value = input.getText().toString().trim();
checklocationTitle();
}
});
alert.setNegativeButton("Cancel",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
dialog.cancel();
}
});
alert.show();
}
public void checklocationTitle() {
if (value.length() > 3) {
Toast.makeText(this, "Name of the locations is know " + value,
Toast.LENGTH_LONG).show();
try {
markedpinpoint = true;
midllat = touchedPoint.getLatitudeE6() / 1E6;
midlongi = touchedPoint.getLongitudeE6() / 1E6;
Geocoder geocoder = new Geocoder(getBaseContext(),
Locale.getDefault());
List<Address> adress = geocoder.getFromLocation(
touchedPoint.getLatitudeE6() / 1E6,
touchedPoint.getLongitudeE6() / 1E6, 1);
if (adress.size() > 0) {
String display = "";
for (int i = 0; i < adress.get(0).getMaxAddressLineIndex(); i++) {
display += adress.get(0).getAddressLine(i) + "\n";
OverlayItem overlayitem = new OverlayItem(touchedPoint,
value, display);
custom = new Location_Service(d, GoogleMaps.this);
custom.insertLocation(overlayitem);
overlayList.add(custom);
}
} else {
Toast.makeText(
this,
"There where a problem to locate the selected adresse",
Toast.LENGTH_LONG).show();
}
} catch (IOException e) {
}
} else {
Toast.makeText(this,
"Please provide a least 3 cifre Title for your location.",
Toast.LENGTH_LONG).show();
addLocation();
}
}
public void buttonLocations(View view) {
// stopLocationListner();
// stopBackgroundService();
Intent intent = new Intent(this, PinPoints.class);
startActivity(intent);
// Toast.makeText(this, "Gemte steder: " + custom.size(),
// Toast.LENGTH_LONG).show();
}
}
public class Location_Service extends ItemizedOverlay<OverlayItem> {
public ArrayList<OverlayItem> pinpoints = new ArrayList<OverlayItem>();
public Location_Service(Drawable defaultMarker) {
super(boundCenter(defaultMarker));
// TODO Auto-generated constructor stub
}
public ArrayList<Locations> getData() {
Locations hej = new Locations();
ArrayList<Locations> tt = new ArrayList<Locations>();
for (OverlayItem test : pinpoints) {
hej.setAdress(test.getSnippet());
hej.setMidlat(test.getPoint().getLatitudeE6());
hej.setMidlong(test.getPoint().getLongitudeE6());
hej.setTitle(test.getTitle());
tt.add(hej);
}
return tt;
}
public Location_Service(Drawable m, Context context) {
this(m);
}
@Override
protected OverlayItem createItem(int i) {
return pinpoints.get(i);
}
@Override
public int size() {
return pinpoints.size();
}
public void insertLocation(OverlayItem item) {
pinpoints.add(item);
this.populate();
}
}
public class Locations {
int midlat;
int midlong;
String title;
String adress;
String distance;
public Locations(String title, String adress, String distance) {
super();
this.title = title;
this.adress = adress;
this.distance = distance;
}
public Locations() {
}
public int getMidlat() {
return midlat;
}
public String getDistance() {
return distance;
}
public void setDistance(String distance) {
this.distance = distance;
}
public void setMidlat(int i) {
this.midlat = i;
}
public int getMidlong() {
return midlong;
}
public void setMidlong(int midlong) {
this.midlong = midlong;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getAdress() {
return adress;
}
public void setAdress(String adress) {
this.adress = adress;
}
@Override
public String toString() {
// TODO Auto-generated method stub
return title + adress + distance;
}
}
问题出现在Toast ......
public class PinPoints extends Activity
{
private ListView lv;
private LocationsAdapter adapter;
private Location_Service locationss;
private ArrayList<Locations> fetch = new ArrayList<Locations>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.locations);
Toast.makeText(this,
"Places: " + locationss.getData(),
Toast.LENGTH_LONG).show();
for (int i = 0; i < 5; i++) {
Locations t = new Locations("Home", "Edvard", "2200m");
fetch.add(t);
}
lv = (ListView) findViewById(R.id.listView1);
adapter = new LocationsAdapter(PinPoints.this, R.id.listView1, fetch);
lv.setAdapter(adapter);
}
}
MyLog档案：
{com.example.test/com.example.test.PinPoints}: java.lang.NullPointerException
01-26 02:27:17.900: E/AndroidRuntime(19389): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2100)
01-26 02:27:17.900: E/AndroidRuntime(19389): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2125)
01-26 02:27:17.900: E/AndroidRuntime(19389): at android.app.ActivityThread.access$600(ActivityThread.java:140)
01-26 02:27:17.900: E/AndroidRuntime(19389): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1227)
01-26 02:27:17.900: E/AndroidRuntime(19389): at android.os.Handler.dispatchMessage(Handler.java:99)
01-26 02:27:17.900: E/AndroidRuntime(19389): at android.os.Looper.loop(Looper.java:137)
01-26 02:27:17.900: E/AndroidRuntime(19389): at android.app.ActivityThread.main(ActivityThread.java:4898)
01-26 02:27:17.900: E/AndroidRuntime(19389): at java.lang.reflect.Method.invokeNative(Native Method)
01-26 02:27:17.900: E/AndroidRuntime(19389): at java.lang.reflect.Method.invoke(Method.java:511)
01-26 02:27:17.900: E/AndroidRuntime(19389): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1008)
01-26 02:27:17.900: E/AndroidRuntime(19389): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:775)
01-26 02:27:17.900: E/AndroidRuntime(19389): at dalvik.system.NativeStart.main(Native Method)
01-26 02:27:17.900: E/AndroidRuntime(19389): Caused by: java.lang.NullPointerException
01-26 02:27:17.900: E/AndroidRuntime(19389): at com.example.test.PinPoints.onCreate(PinPoints.java:31)
01-26 02:27:17.900: E/AndroidRuntime(19389): at android.app.Activity.performCreate(Activity.java:5206)
01-26 02:27:17.900: E/AndroidRuntime(19389): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1094)
01-26 02:27:17.900: E/AndroidRuntime(19389): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2064)
01-26 02:27:17.900: E/AndroidRuntime(19389): ... 11 more
答案 0 :(得分：1)
在onCreate中未初始化位置，因此您将获得空指针异常。您应该在使用它之前对其进行初始化
答案 1 :(得分：0)
没有看到崩溃转储是一个猜测游戏。当您尝试将数据显示在吐司中时，我认为locationss为null。因此，当您调用locationss.getData()时，您会收到NullReferenceException。
答案 2 :(得分：0)
可能您遇到了calling populate inappropriately问题。只是从其他问题的答案摘要中，您应该在填充任何数据之前在ItemizedOverlay中调用populate（）