这是xml代码:
<LinearLayout
android:id="@+id/mainLayout"
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity"
android:orientation="vertical"
android:background="@color/black" >
<ScrollView
android:id="@+id/mainScrollView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="@color/teal"
android:layout_weight=".50">
<LinearLayout
android:id="@+id/linearLayout1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
</LinearLayout>
</ScrollView>
<Button
android:id="@+id/addButton"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="+"
android:gravity="center"
android:layout_weight=".20"
/>
<TextView
android:id="@+id/totalHoursLabel"
android:text="Ore Totali"
android:background="@color/gray"
android:textColor="@color/red"
android:gravity="center"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight=".10"
/>
<TextView
android:id="@+id/totalHoursView"
android:text="00:00"
android:background="@color/white"
android:textColor="@color/black"
android:gravity="center"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight=".20"
/>
</LinearLayout>
我的问题是,当我尝试向 ScrollView 或他的内部 LinearLayout 添加视图时,我的程序崩溃了。
这是我的java代码:
super.onCreate(savedInstanceState);
LinearLayout ll = (LinearLayout) findViewById(R.id.linearLayout1);
TextView tv = new TextView(this);
tv.setText("testView");
tv.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
ll.addView(tv);
setContentView(R.layout.activity_main);
如果我创建一个新的 android 项目,这个代码(只有一个 relativeLayout 和 xml 文件中的所有其他内容)工作正常。
我认为 findViewById 方法或我的 xml 文件存在一些问题。
有任何想法吗?
这是我的 LogCat 文件:
07-23 15:56:19.119: D/AndroidRuntime(1249): Shutting down VM
07-23 15:56:19.119: W/dalvikvm(1249): threadid=1: thread exiting with uncaught exception (group=0x40a71930)
07-23 15:56:19.159: E/AndroidRuntime(1249): FATAL EXCEPTION: main
07-23 15:56:19.159: E/AndroidRuntime(1249): java.lang.RuntimeException: Unable to start activity ComponentInfo{workTimer.worktimer/workTimer.worktimer.MainActivity}: java.lang.NullPointerException
07-23 15:56:19.159: E/AndroidRuntime(1249): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
07-23 15:56:19.159: E/AndroidRuntime(1249): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
07-23 15:56:19.159: E/AndroidRuntime(1249): at android.app.ActivityThread.access$600(ActivityThread.java:141)
07-23 15:56:19.159: E/AndroidRuntime(1249): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
07-23 15:56:19.159: E/AndroidRuntime(1249): at android.os.Handler.dispatchMessage(Handler.java:99)
07-23 15:56:19.159: E/AndroidRuntime(1249): at android.os.Looper.loop(Looper.java:137)
07-23 15:56:19.159: E/AndroidRuntime(1249): at android.app.ActivityThread.main(ActivityThread.java:5041)
07-23 15:56:19.159: E/AndroidRuntime(1249): at java.lang.reflect.Method.invokeNative(Native Method)
07-23 15:56:19.159: E/AndroidRuntime(1249): at java.lang.reflect.Method.invoke(Method.java:511)
07-23 15:56:19.159: E/AndroidRuntime(1249): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
07-23 15:56:19.159: E/AndroidRuntime(1249): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
07-23 15:56:19.159: E/AndroidRuntime(1249): at dalvik.system.NativeStart.main(Native Method)
07-23 15:56:19.159: E/AndroidRuntime(1249): Caused by: java.lang.NullPointerException
07-23 15:56:19.159: E/AndroidRuntime(1249): at workTimer.worktimer.MainActivity.onCreate(MainActivity.java:32)
07-23 15:56:19.159: E/AndroidRuntime(1249): at android.app.Activity.performCreate(Activity.java:5104)
07-23 15:56:19.159: E/AndroidRuntime(1249): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
07-23 15:56:19.159: E/AndroidRuntime(1249): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
07-23 15:56:19.159: E/AndroidRuntime(1249): ... 11 more
07-23 15:56:22.649: I/Process(1249): Sending signal. PID: 1249 SIG: 9