当我尝试创建文本视图并将其链接到应用程序中的XML组件时,我的应用程序似乎崩溃了。 我使用的代码是:
public class WorkoutAdvice extends Activity {
TextView adviceshow;
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
String[] advice = getResources().getStringArray(R.array.races_array);
Random rand = new Random();
int ad = rand.nextInt(5);
String gen = advice[ad];
adviceshow = (TextView)findViewById(R.id.advice);
adviceshow.setText(gen);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.advice);
}
}
当我的应用程序关闭时,日志是
05-26 01:43:23.018: E/Android运行时(363): 致命异常: 主 05-26 01:43:23.018: E/AndroidRuntime(363): java.lang.RuntimeException: 无法启动活动 ComponentInfo{com.b00348312.workout/com.b00348312.workout.workoutAdvice}: java.lang.NullPointerException 05-26 01:43:23.018: E/AndroidRuntime(363): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663) 05-26 01:43:23.018: E/AndroidRuntime(363): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679) 05-26 01:43:23.018: E/AndroidRuntime(363): at android.app.ActivityThread.access$2300(ActivityThread.java:125) 05-26 01:43:23.018: E/AndroidRuntime(363): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033) 05-26 01:43:23.018: E/AndroidRuntime(363): at android.os.Handler.dispatchMessage(Handler.java:99) 05-26 01:43:23.018: E/AndroidRuntime(363): at android.os.Looper.loop(Looper.java:123) 05-26 01:43:23.018: E/AndroidRuntime(363): at android.app.ActivityThread.main(ActivityThread.java:4627) 05-26 01:43:23.018: E/AndroidRuntime(363): at java.lang.reflect.Method.invokeNative(Native Method) 05-26 01:43:23.018: E/AndroidRuntime(363): at java.lang.reflect.Method.invoke(Method.java:521) 05-26 01:43:23.018: E/AndroidRuntime(363): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 05-26 01:43:23.018: E/AndroidRuntime(363): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) 05-26 01:43:23.018: E/AndroidRuntime(363): at dalvik.system.NativeStart.main(Native Method) 05-26 01:43:23.018: E/AndroidRuntime(363): 由: java.lang.NullPointerException 引起 05-26 01:43:23.018: E/AndroidRuntime(363): at com.b00348312.workout.WorkoutAdvice.onCreate(WorkoutAdvice.java:22) 05-26 01:43:23.018: E/AndroidRuntime(363): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 05-26 01:43:23.018: E/AndroidRuntime(363): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627) 05-26 01:43:23.018: E/Android运行时(363): ...11 更多
应用程序在没有处理 findbyID 行的语句的情况下工作,这些语句在应用程序的其他部分工作
在通过调用 setContentView
实际设置活动内容之前,找不到任何视图。一旦你打电话给setContentView
,那么你就可以尝试找到你的TextView
。请注意,在此调用之前,Activity
根本不知道它将绑定到哪些 XML 布局(如果有)。
Put
setContentView(R.layout.advice);
之前
adviceshow = (TextView)findViewById(R.id.advice);
我认为你应该在使用findViewById之前设置ContentView。
public class WorkoutAdvice extends Activity {
TextView adviceshow;
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.advice);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN);
adviceshow = (TextView)findViewById(R.id.advice);
String[] advice = getResources().getStringArray(R.array.races_array);
Random rand = new Random();
int ad = rand.nextInt(5);
String gen = advice[ad];
adviceshow.setText(gen);
}}
应该是这样的