Question

当我尝试在下面的代码中填充'lightName'TextView时，这可以正常工作，但是当我尝试使用'pressureName'时，我的应用程序崩溃了

public class ViewSensorData extends ActionBarActivity {

    TextView lightName;
    TextView pressureName;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_sensor_data);

        lightName = (TextView) findViewById(R.id.sensor_name_1);
        lightName.setText(R.string.display_light);

        pressureName = (TextView) findViewById(R.id.sensor_name_4);
        pressureName.setText(R.string.display_pressure);
    }
}

activity_sensor_data.xml文件看起来像是

<GridLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="horizontal"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.mycompany.myfirstapp.ViewSensorData">

    <TextView
        android:layout_width="211dp"
        android:layout_height="wrap_content"
        android:id="@+id/sensor_name_1"
        android:layout_row="1"
        android:layout_column="1" />

    <TextView
        android:layout_width="211dp"
        android:layout_height="wrap_content"
        android:id="@+id/sensor_name_4"
        android:layout_row="4"
        android:layout_column="1" />
</GridLayout>

最后，我的logcat看起来像这样

02-19 23:44:39.071    2685-2685/com.mycompany.myfirstapp I/PersonaManager﹕ getPersonaService() name persona_policy
02-19 23:44:39.101    2685-2685/com.mycompany.myfirstapp D/AndroidRuntime﹕ Shutting down VM
02-19 23:44:39.101    2685-2685/com.mycompany.myfirstapp W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x418afda0)
02-19 23:44:39.101    2685-2685/com.mycompany.myfirstapp E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.mycompany.myfirstapp, PID: 2685
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.mycompany.myfirstapp/com.mycompany.myfirstapp.ViewSensorData}: java.lang.NullPointerException
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2305)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2363)
            at android.app.ActivityThread.access$900(ActivityThread.java:161)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1265)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:157)
            at android.app.ActivityThread.main(ActivityThread.java:5356)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.NullPointerException
            at com.mycompany.myfirstapp.ViewSensorData.onCreate(ViewSensorData.java:32)
            at android.app.Activity.performCreate(Activity.java:5426)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2269)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2363)
            at android.app.ActivityThread.access$900(ActivityThread.java:161)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1265)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:157)
            at android.app.ActivityThread.main(ActivityThread.java:5356)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
            at dalvik.system.NativeStart.main(Native Method)
02-19 23:49:39.173    2685-2685/com.mycompany.myfirstapp I/Process﹕ Sending signal. PID: 2685 SIG: 9

Answer 1

您应该通过其ID来获取资源，而不是设置它

lightName.setText(getResources().getString(R.string.display_light));

Answer 2

在这里羞愧我的头。我已将最小SDK更改为14，而后者又生成了另一个activity_sensor_data.xml(v14)文件。编辑此文件后，pressureName TextView会按预期填充。

试图setText（）崩溃Android应用程序

2 个答案: