Question

我正在使用GoogleMaps编写应用程序。我现在在模拟器上运行它。下面的布局适用于app。地图绘制好了。我想在屏幕上有一些额外的TextViews和按钮与地图。但是我有运行时错误，如果我向我的XML添加第二个TextView或按钮。如果我在一些LinearLayout中添加它们，我也会收到错误。

<?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
          android:layout_width="fill_parent"
          android:layout_height="fill_parent"
          android:background="@color/backNormal"
          android:orientation="vertical"
    >
<TextView
        android:id="@+id/mytext2"
        android:gravity="center"
        android:text='My Text'
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        style="@style/text_style_title"
        />
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="fill_parent"
              android:layout_height="match_parent"
              android:background="@color/backNormal"
              android:orientation="vertical"
        >
    <fragment
            android:id="@+id/map"
            android:name="com.google.android.gms.maps.MapFragment"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            />
</LinearLayout>
</LinearLayout>

错误文字如下：

3459-3459/moorlakgames.packet1 E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: moorlakgames.packet1, PID: 3459
    java.lang.RuntimeException: Unable to start activity ComponentInfo{moorlakgames.packet1/moorlakgames.packet1.MyActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'com.google.android.gms.maps.GoogleMap com.google.android.gms.maps.MapFragment.getMap()' on a null object reference
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
            at android.app.ActivityThread.access$800(ActivityThread.java:144)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5221)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'com.google.android.gms.maps.GoogleMap com.google.android.gms.maps.MapFragment.getMap()' on a null object reference

正如我所说，它在布局中使用一个TextView，但不适用于两个TextView。有任何想法吗？谢谢！

Answer 1

试试这个

<?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
          android:layout_width="fill_parent"
          android:layout_height="fill_parent"
          android:background="@color/backNormal"
          android:orientation="vertical"
    >
<TextView
        android:id="@+id/mytext2"
        android:gravity="center"
        android:text='My Text'
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        style="@style/text_style_title"/>
   <LinearLayout 
        android:id="@+id/myLayout"
        android:layout_width="fill_parent"
        android:layout_height="match_parent"
        android:background="@color/backNormal"
        android:orientation="vertical">
    <fragment
          android:id="@+id/map"
          android:name="com.google.android.gms.maps.MapFragment"
          android:layout_width="match_parent"
          android:layout_height="match_parent"/>
  </LinearLayout>
</LinearLayout>

Answer 2

对于将来的情况，使用缩进，它将使您的生活更轻松。

如果以上XML是您的整个布局，您仍然无法关闭外部LinearLayout，这可能会导致LayoutInflater夸大空View，从而导致您获得执行

时NullPointerException

((MapFragment)findViewById(R.id.map)).getMap();

GoogleMap应用中的运行时错误

2 个答案: