我正在通过观看Thenewboston的视频来练习Android开发。
从他的一个视频中，我正在尝试制作onTouchEvent()，但我收到错误：Java.lang.NullPointerException。
The newboston 134 number tutorial
我该怎么办？
现在整个代码是：
package com.chupamobile.android.googlemaps;
import java.util.List;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.os.Bundle;
import android.view.MotionEvent;
import com.google.android.maps.MapActivity;
import com.google.android.maps.MapView;
import com.google.android.maps.Overlay;
public class GoogleMapsActivity extends MapActivity {
MapView map;
Long start, stop;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
map = (MapView) findViewById(R.id.mymap);
map.setBuiltInZoomControls(true);
Touchy t = new Touchy();
List<Overlay> overlayList = map.getOverlays();
overlayList.add(t);
}
@Override
protected boolean isRouteDisplayed() {
// TODO Auto-generated method stub
return false;
}
class Touchy extends Overlay {
public boolean onTouchEvent(MotionEvent e, MapView m) {
if (e.getAction() == MotionEvent.ACTION_DOWN) {
start = e.getEventTime();
}
if (e.getAction() == MotionEvent.ACTION_UP) {
stop = e.getEventTime();
}
if (stop - start > 1500) {
AlertDialog alert = new AlertDialog.Builder(
GoogleMapsActivity.this).create();
alert.setTitle("Pick an option");
alert.setMessage("I told u pick an option");
alert.setButton("Place a pin",
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog,
int which) {
// TODO Auto-generated method stub
}
});
alert.show();
return true;
}
return false;
}
}
}
我的错误列表：
Warning: 10-16 10:06:57.106: E/MapActivity(1649): Couldn't get connection factory client
10-16 10:07:03.645: W/dalvikvm(1649): threadid=1: thread exiting with uncaught exception (group=0x409c01f8)
10-16 08:17:31.174: W/dalvikvm(1349): threadid=1: thread exiting with uncaught exception (group=0x409c01f8)
10-16 08:17:31.334: E/AndroidRuntime(1349): FATAL EXCEPTION: main
10-16 08:17:31.334: E/AndroidRuntime(1349): java.lang.NullPointerException
10-16 08:17:31.334: E/AndroidRuntime(1349): at com.chupamobile.android.googlemaps.GoogleMapsActivity$Touchy.onTouchEvent(GoogleMapsActivity.java:45)
10-16 08:17:31.334: E/AndroidRuntime(1349): at com.google.android.maps.OverlayBundle.onTouchEvent(OverlayBundle.java:63)
10-16 08:17:31.334: E/AndroidRuntime(1349): at com.google.android.maps.MapView.onTouchEvent(MapView.java:679)
10-16 08:17:31.334: E/AndroidRuntime(1349): at android.view.View.dispatchTouchEvent(View.java:5541)
10-16 08:17:31.334: E/AndroidRuntime(1349): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1951)
10-16 08:17:31.334: E/AndroidRuntime(1349): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1712)
10-16 08:17:31.334: E/AndroidRuntime(1349): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1957)
10-16 08:17:31.334: E/AndroidRuntime(1349): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1684)
10-16 08:17:31.334: E/AndroidRuntime(1349): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1957)
10-16 08:17:31.334: E/AndroidRuntime(1349): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1684)
10-16 08:17:31.334: E/AndroidRuntime(1349): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1957)
10-16 08:17:31.334: E/AndroidRuntime(1349): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1684)
10-16 08:17:31.334: E/AndroidRuntime(1349): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1957)
10-16 08:17:31.334: E/AndroidRuntime(1349): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1684)
10-16 08:17:31.334: E/AndroidRuntime(1349): at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1912)
10-16 08:17:31.334: E/AndroidRuntime(1349): at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1371)
10-16 08:17:31.334: E/AndroidRuntime(1349): at android.app.Activity.dispatchTouchEvent(Activity.java:2364)
10-16 08:17:31.334: E/AndroidRuntime(1349): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1860)
10-16 08:17:31.334: E/AndroidRuntime(1349): at android.view.View.dispatchPointerEvent(View.java:5721)
10-16 08:17:31.334: E/AndroidRuntime(1349): at android.view.ViewRootImpl.deliverPointerEvent(ViewRootImpl.java:2890)
10-16 08:17:31.334: E/AndroidRuntime(1349): at android.view.ViewRootImpl.handleMessage(ViewRootImpl.java:2466)
10-16 08:17:31.334: E/AndroidRuntime(1349): at android.view.ViewRootImpl.processInputEvents(ViewRootImpl.java:845)
10-16 08:17:31.334: E/AndroidRuntime(1349): at android.view.ViewRootImpl.handleMessage(ViewRootImpl.java:2475)
10-16 08:17:31.334: E/AndroidRuntime(1349): at android.os.Handler.dispatchMessage(Handler.java:99)
10-16 08:17:31.334: E/AndroidRuntime(1349): at android.os.Looper.loop(Looper.java:137)
10-16 08:17:31.334: E/AndroidRuntime(1349): at android.app.ActivityThread.main(ActivityThread.java:4424)
10-16 08:17:31.334: E/AndroidRuntime(1349): at java.lang.reflect.Method.invokeNative(Native Method)
10-16 08:17:31.334: E/AndroidRuntime(1349): at java.lang.reflect.Method.invoke(Method.java:511)
10-16 08:17:31.334: E/AndroidRuntime(1349): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
10-16 08:17:31.334: E/AndroidRuntime(1349): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
10-16 08:17:31.334: E/AndroidRuntime(1349): at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：4)
尝试创建OnTouchListner。
例如
button.setOnTouchListener(new View.OnTouchListener()
{
public void onClick(View v)
{
}
答案 1 :(得分：0)
说你需要在按钮中点击触摸（即点击我猜的事件），而不是在你的xml代码中添加这个
android:onClick=onClick
并在你的oncreate方法之后的活动中写下这个
public void onClick(View v){
switch(v.getId()){
case R.id.urbuttonid:{
Log.e("click event fired?","yes");
break;
}
}
}
执行此操作后检查您的日志
答案 2 :(得分：0)
在上面的代码中，我使用了Long start, stop;而不是long start, stop;这是错误。