我正在尝试在安卓应用程序中切换不同的页面,当我运行项目时,它会将我带到模拟器屏幕,但是会出现错误消息:
以下是.java文件中的代码:
![enter image description here](https://istack.dev59.com/CN9rH.webp)
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final Spinner spinner = (Spinner)findViewById(R.id.spinner1);
ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(
this, R.array.MyPictures, android.R.layout.simple_spinner_item);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner.setAdapter(adapter);
final Button button = (Button) findViewById(R.id.button02);
button.setOnClickListener(new View.OnClickListener(){
public void onClick(View v){
setContentView(R.layout.imageview);
}
});
}
日志记录器:
02-27 11:58:41.374: D/AndroidRuntime(313): Shutting down VM
02-27 11:58:41.374: W/dalvikvm(313): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
02-27 11:58:41.454: E/AndroidRuntime(313): FATAL EXCEPTION: main
02-27 11:58:41.454: E/AndroidRuntime(313): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.test/com.example.test.MainActivity}: java.lang.NullPointerException
02-27 11:58:41.454: E/AndroidRuntime(313): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
02-27 11:58:41.454: E/AndroidRuntime(313): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
02-27 11:58:41.454: E/AndroidRuntime(313): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
02-27 11:58:41.454: E/AndroidRuntime(313): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
02-27 11:58:41.454: E/AndroidRuntime(313): at android.os.Handler.dispatchMessage(Handler.java:99)
02-27 11:58:41.454: E/AndroidRuntime(313): at android.os.Looper.loop(Looper.java:123)
02-27 11:58:41.454: E/AndroidRuntime(313): at android.app.ActivityThread.main(ActivityThread.java:4627)
02-27 11:58:41.454: E/AndroidRuntime(313): at java.lang.reflect.Method.invokeNative(Native Method)
02-27 11:58:41.454: E/AndroidRuntime(313): at java.lang.reflect.Method.invoke(Method.java:521)
02-27 11:58:41.454: E/AndroidRuntime(313): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
02-27 11:58:41.454: E/AndroidRuntime(313): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
02-27 11:58:41.454: E/AndroidRuntime(313): at dalvik.system.NativeStart.main(Native Method)
02-27 11:58:41.454: E/AndroidRuntime(313): Caused by: java.lang.NullPointerException
02-27 11:58:41.454: E/AndroidRuntime(313): at com.example.test.MainActivity.onCreate(MainActivity.java:29)
02-27 11:58:41.454: E/AndroidRuntime(313): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
02-27 11:58:41.454: E/AndroidRuntime(313): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
02-27 11:58:41.454: E/AndroidRuntime(313): ... 11 more
我有没有意识到的错误?
这是我的第二个项目,显示相同的错误。谢谢。
MainActivity
中的第29行是什么? - Kaushik