我正在尝试将数据从一个页面传输到另一个页面，但下面的一些问题是代码。我试图使用捆绑从第一个活动转移到第二个变量的值，但有些错误请告诉我哪里出错了。
以下是第一项活动： -
public class login extends Activity {
/** Called when the activity is first created. */
Context mCtx;
final static int START =0;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mCtx = this;
Button btn = (Button)findViewById(R.id.btn);
btn.setOnClickListener(new OnClickListener(){
// @Override
public void onClick(View v)
{
String fromLat = new String();
String fromLong = new String();
String toLat = new String();
String toLong = new String();
fromLat = ((EditText)findViewById(R.id.FromLatitude)).getText().toString();
fromLong = ((EditText)findViewById(R.id.FromLongitude)).getText().toString();
toLat = ((EditText)findViewById(R.id.ToLatitude)).getText().toString();
toLong = ((EditText)findViewById(R.id.ToLongitude)).getText().toString();
Intent intent = new Intent(mCtx, MapRouteActivity.class);
/*Sending some arguments*/
Bundle bundle = new Bundle(4);
bundle.putString("fromLat",fromLat );
bundle.putString("fromLong",fromLong );
bundle.putString("toLat",toLat );
bundle.putString("toLong",toLong );
intent.putExtras(bundle);
/*Start Activity*/
mCtx.startActivity(intent);
/*Start ActivityForResult*/
((Activity)mCtx).startActivityForResult(intent, 2);
}
});
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
// TODO Auto-generated method stub
super.onActivityResult(requestCode, resultCode, data);
if(requestCode == START)
{
Toast.makeText(mCtx, Integer.toString(resultCode), Toast.LENGTH_SHORT).show();
}
}
@Override
public void onDestroy(){
super.onDestroy();
finish();
}
}
以下是第二项活动： -
public class MapRouteActivity extends MapActivity {
LinearLayout linearLayout;
MapView mapView;
private Road mRoad;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.routeplanning);
mapView = (MapView) findViewById(R.id.mapview);
mapView.setBuiltInZoomControls(true);
Bundle extras = this.getIntent().getExtras();
String fLat=extras.getString("fromLat");
String fLong=extras.getString("fromLong");
String tLat=extras.getString("toLat");
String tLong=extras.getString("toLong");
final double fromLat=Double.parseDouble(fLat);
final double fromLon=Double.parseDouble(fLong);
final double toLat=Double.parseDouble(tLat);
final double toLon=Double.parseDouble(tLong);
new Thread() {
@Override
public void run() {
//double fromLat = 28.6353, fromLon = 77.2250, toLat = 30.7313, toLon = 76.7754;
/***url contains the path to fetch the kml file from the internet*/
String url = RoadProvider
.getUrl(fromLat, fromLon, toLat, toLon);
InputStream is = getConnection(url);
mRoad = RoadProvider.getRoute(is);
mHandler.sendEmptyMessage(0);
}
}.start();
}
Handler mHandler = new Handler() {
public void handleMessage(android.os.Message msg) {
TextView textView = (TextView) findViewById(R.id.description);
textView.setText(mRoad.mName + " " + mRoad.mDescription);
MapOverlay mapOverlay = new MapOverlay(mRoad, mapView);
List<Overlay> listOfOverlays = mapView.getOverlays();
listOfOverlays.clear();
listOfOverlays.add(mapOverlay);
mapView.invalidate();
};
};
private InputStream getConnection(String url) {
InputStream is = null;
try {
//Opens a connection to the remote database(bidirectional)
URLConnection conn = new URL(url).openConnection();
is = conn.getInputStream();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return is;
}
@Override
protected boolean isRouteDisplayed() {
return false;
}
}
class MapOverlay extends com.google.android.maps.Overlay {
Road mRoad;
ArrayList<GeoPoint> mPoints;
public MapOverlay(Road road, MapView mv) {
mRoad = road;
if (road.mRoute.length > 0) {
mPoints = new ArrayList<GeoPoint>();
for (int i = 0; i < road.mRoute.length; i++) {
mPoints.add(new GeoPoint((int) (road.mRoute[i][1] * 1000000),
(int) (road.mRoute[i][0] * 1000000)));
}
int moveToLat = (mPoints.get(0).getLatitudeE6() + (mPoints.get(
mPoints.size() - 1).getLatitudeE6() - mPoints.get(0)
.getLatitudeE6()) / 2);
int moveToLong = (mPoints.get(0).getLongitudeE6() + (mPoints.get(
mPoints.size() - 1).getLongitudeE6() - mPoints.get(0)
.getLongitudeE6()) / 2);
GeoPoint moveTo = new GeoPoint(moveToLat, moveToLong);
MapController mapController = mv.getController();
mapController.animateTo(moveTo);
mapController.setZoom(9);
}
}
@Override
public boolean draw(Canvas canvas, MapView mv, boolean shadow, long when) {
super.draw(canvas, mv, shadow);
drawPath(mv, canvas);
return true;
}
public void drawPath(MapView mv, Canvas canvas) {
int x1 = -1, y1 = -1, x2 = -1, y2 = -1;
Paint paint = new Paint();
paint.setColor(Color.GREEN);
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeWidth(3);
for (int i = 0; i < mPoints.size(); i++) {
Point point = new Point();
mv.getProjection().toPixels(mPoints.get(i), point);
x2 = point.x;
y2 = point.y;
if (i > 0) {
canvas.drawLine(x1, y1, x2, y2, paint);
}
x1 = x2;
y1 = y2;
}
}
}
按下按钮时，应用程序强制关闭。
以下是强制关闭应用程序的LogCat数据
02-02 15:32:31.837: ERROR/AndroidRuntime(199): Uncaught handler: thread main exiting due to uncaught exception
02-02 15:32:31.857: ERROR/AndroidRuntime(199): java.lang.NullPointerException
02-02 15:32:31.857: ERROR/AndroidRuntime(199): at route.planning.login$1.onClick(login.java:49)
02-02 15:32:31.857: ERROR/AndroidRuntime(199): at android.view.View.performClick(View.java:2344)
02-02 15:32:31.857: ERROR/AndroidRuntime(199): at android.view.View.onTouchEvent(View.java:4133)
02-02 15:32:31.857: ERROR/AndroidRuntime(199): at android.widget.TextView.onTouchEvent(TextView.java:6504)
02-02 15:32:31.857: ERROR/AndroidRuntime(199): at android.view.View.dispatchTouchEvent(View.java:3672)
02-02 15:32:31.857: ERROR/AndroidRuntime(199): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:882)
02-02 15:32:31.857: ERROR/AndroidRuntime(199): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:882)
02-02 15:32:31.857: ERROR/AndroidRuntime(199): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:882)
02-02 15:32:31.857: ERROR/AndroidRuntime(199): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:882)
02-02 15:32:31.857: ERROR/AndroidRuntime(199): at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1712)
02-02 15:32:31.857: ERROR/AndroidRuntime(199): at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1202)
02-02 15:32:31.857: ERROR/AndroidRuntime(199): at android.app.Activity.dispatchTouchEvent(Activity.java:1987)
02-02 15:32:31.857: ERROR/AndroidRuntime(199): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1696)
02-02 15:32:31.857: ERROR/AndroidRuntime(199): at android.view.ViewRoot.handleMessage(ViewRoot.java:1658)
02-02 15:32:31.857: ERROR/AndroidRuntime(199): at android.os.Handler.dispatchMessage(Handler.java:99)
02-02 15:32:31.857: ERROR/AndroidRuntime(199): at android.os.Looper.loop(Looper.java:123)
02-02 15:32:31.857: ERROR/AndroidRuntime(199): at android.app.ActivityThread.main(ActivityThread.java:4203)
02-02 15:32:31.857: ERROR/AndroidRuntime(199): at java.lang.reflect.Method.invokeNative(Native Method)
02-02 15:32:31.857: ERROR/AndroidRuntime(199): at java.lang.reflect.Method.invoke(Method.java:521)
02-02 15:32:31.857: ERROR/AndroidRuntime(199): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791)
02-02 15:32:31.857: ERROR/AndroidRuntime(199): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:549)
02-02 15:32:31.857: ERROR/AndroidRuntime(199): at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：1)
login.java第49行是什么？
一些建议：类应始终以大写字母开头，因此登录而不是登录