我正在尝试将数据从一页传输到另一页,但是下面的代码是一些问题。我正在尝试使用捆绑包将变量的值从第一个活动转移到第二个活动,但是出了点问题,请告诉我出了什么问题。

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;
            }
    }

}


按下按钮后,应用程序被强制关闭。

以下是有关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)

最佳答案

login.java的第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

关于android - 如何将一项 Activity 的输入转移到另一项 Activity ?,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/4873185/

10-12 00:25