Android从另一个类中的方法调用意图

我有一个在点击时创建弹出窗口的方法，叫做

onballoottap

，我正试图在另一个类

pip

中调用

CallPopup（）

。我做错了什么？我是否应该通过方法调用intent？我的目标是在调用

onballoottap

时启动另一个活动。有更好的方法吗

pip中的
CallPopUp（）

public void CallPopup()
{   Log.i("CallPopup", "Started CallPopup");
    startActivity(intent);
    finish();
}

从另一个类中的
onballoottap
调用

protected boolean onBalloonTap(int index, OverlayItem item) {
    Toast.makeText(c, "onBalloonTap for overlay index " + index,
            Toast.LENGTH_LONG).show();
    pip pipinst =new pip();
    pipinst.CallPopup();
    return true;
}

我得到这个日志：

05-04 22:33:41.022: ERROR/AndroidRuntime(704): FATAL EXCEPTION: main
05-04 22:33:41.022: ERROR/AndroidRuntime(704): java.lang.NullPointerException
05-04 22:33:41.022: ERROR/AndroidRuntime(704):     at android.app.Activity.startActivityForResult(Activity.java:2817)
05-04 22:33:41.022: ERROR/AndroidRuntime(704):     at android.app.Activity.startActivity(Activity.java:2923)
05-04 22:33:41.022: ERROR/AndroidRuntime(704):     at com.appname.pip.pip.CallPopup(pip.java:192)
05-04 22:33:41.022: ERROR/AndroidRuntime(704):     at com.appname.pip.MyItemizedOverlay.onBalloonTap(MyItemizedOverlay.java:67)
05-04 22:33:41.022: ERROR/AndroidRuntime(704):     at com.readystatesoftware.mapviewballoons.BalloonItemizedOverlay$1.onTouch(BalloonItemizedOverlay.java:203)
05-04 22:33:41.022: ERROR/AndroidRuntime(704):     at android.view.View.dispatchTouchEvent(View.java:3762)
05-04 22:33:41.022: ERROR/AndroidRuntime(704):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:897)
05-04 22:33:41.022: ERROR/AndroidRuntime(704):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:936)
05-04 22:33:41.022: ERROR/AndroidRuntime(704):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:936)
05-04 22:33:41.022: ERROR/AndroidRuntime(704):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:936)
05-04 22:33:41.022: ERROR/AndroidRuntime(704):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:936)
05-04 22:33:41.022: ERROR/AndroidRuntime(704):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:936)
05-04 22:33:41.022: ERROR/AndroidRuntime(704):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:936)
05-04 22:33:41.022: ERROR/AndroidRuntime(704):     at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1671)
05-04 22:33:41.022: ERROR/AndroidRuntime(704):     at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1107)
05-04 22:33:41.022: ERROR/AndroidRuntime(704):     at android.app.Activity.dispatchTouchEvent(Activity.java:2086)
05-04 22:33:41.022: ERROR/AndroidRuntime(704):     at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1655)
05-04 22:33:41.022: ERROR/AndroidRuntime(704):     at android.view.ViewRoot.handleMessage(ViewRoot.java:1785)
05-04 22:33:41.022: ERROR/AndroidRuntime(704):     at android.os.Handler.dispatchMessage(Handler.java:99)
05-04 22:33:41.022: ERROR/AndroidRuntime(704):     at android.os.Looper.loop(Looper.java:123)
05-04 22:33:41.022: ERROR/AndroidRuntime(704):     at android.app.ActivityThread.main(ActivityThread.java:4627)
05-04 22:33:41.022: ERROR/AndroidRuntime(704):     at java.lang.reflect.Method.invokeNative(Native Method)
05-04 22:33:41.022: ERROR/AndroidRuntime(704):     at java.lang.reflect.Method.invoke(Method.java:521)
05-04 22:33:41.022: ERROR/AndroidRuntime(704):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
05-04 22:33:41.022: ERROR/AndroidRuntime(704):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
05-04 22:33:41.022: ERROR/AndroidRuntime(704):     at dalvik.system.NativeStart.main(Native Method)
05-04 22:33:41.102: WARN/ActivityManager(38):   Force finishing activity com.appname.pip/.pip
05-04 22:33:41.952: WARN/ActivityManager(38): Activity pause timeout for HistoryRecord{43f680f0 com.appname.pip/.pip}

您需要声明在
CallPopup（）中使用的
intent
这可能是您获得
NullPointerException
的原因。看起来“pip”类扩展了活动，但您只是创建了一个pip对象，而没有经历任何活动生命周期。空指针异常可能是因为pip对象不知道其父上下文是什么。您几乎肯定可以访问OnBallootTap中的上下文对象（例如），所以为什么不直接从那里调用呢