메소드간에 LinearLayout, RelativeLayout 및 TextView를 전달하는 Android

Question

특정 TextView를 업데이트하는 스레드를 만들려고합니다. onCreate() 메서드에서 LinearLayout, RelativeLayout 및 TextView를 이미 설정했습니다. 나는 단지 그 정보를 업데이트하기를 원할 뿐이다. 모든 것이 잘 컴파일됩니다. 휴대 전화에서 실행하면 강제 실행 시간 오류가 발생합니다.

문제가 onRefresh (...) {와 관련되어 있고 그 정보를 어떻게 전달했는지 알고 있습니다. 누구든지 정보를 올바르게 전달하는 방법을 명확히 할 수 있습니까?

감사합니다.

@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 

    //Define String(s) 
    String infoText = "Push button to test"; 
    String buttonLabelA = "Show Hello!"; 

    //Setup screen orientation 
    LinearLayout mainWindow = new LinearLayout(this); 
    mainWindow.setOrientation(LinearLayout.VERTICAL); 

    //Set title 
    setTitle("JOHello"); 

    //Set the static text that will appear in the window 
    TextView label = new TextView(this); 
    label.setText(infoText); 
    RelativeLayout.LayoutParams params1 = new RelativeLayout.LayoutParams(400, 50); 
    params1.leftMargin = 15; 
    params1.topMargin = 5; 
    mainWindow.addView(label, params1); 

    //Set button 
    Button greetingButton = new Button(this);//instantiate greeting button 
    greetingButton.setText(buttonLabelA);//set button text 
    mVB localVB = new mVB(); 
    greetingButton.setOnClickListener(localVB);//link button click to event 
    RelativeLayout.LayoutParams params2 = new RelativeLayout.LayoutParams(200, 75); 
    params2.leftMargin = 100; 
    params2.topMargin = 100; 
    mainWindow.addView(greetingButton, params2);//add button to current view*/ 


    //Changeable text 
    TextView chgTxt = new TextView(this); 
    chgTxt.setText(localVB.greetingText); 
    RelativeLayout.LayoutParams params3 = new RelativeLayout.LayoutParams(400, 50); 
    params3.leftMargin = 15; 
    params3.topMargin = 600; 
    mainWindow.addView(chgTxt, params3); 


    setContentView(mainWindow); 

    doRefresh(mainWindow, params3, chgTxt); 
} 




private void doRefresh(final LinearLayout localWindow, final RelativeLayout.LayoutParams localParams, final TextView localText){ 
    handler.postDelayed(new Runnable() { 
     @Override 
     public void run() { 
      localText.setText("It truly works!"); 
      localWindow.addView(localText, localParams); 
     } 
    }, 1000); 
} 

글로벌 변수를 만들었습니다!

02-13 23 : 32 : 56.204 : 여기

public class MainActivity extends Activity { 

private final Handler handler = new Handler();//Hanging!? 
public LinearLayout mainWindow = new LinearLayout(this); 
public TextView mainText = new TextView(this); 
public RelativeLayout.LayoutParams mainParams = new RelativeLayout.LayoutParams(400, 50); 


@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 

... 
} 

public void doRefresh(){ 
    handler.postDelayed(new Runnable() { 
     @Override 
     public void run() { 
      mainText.setText("It fucking works"); 
      mainWindow.addView(mainText, mainParams); 
     } 
    }, 1000); 
} 

로그 고양이 :이 핸들러가 선언 될 때 중단 어디 지금 런타임 문제가 E/AndroidRuntime (11184) : ... 당신의 도움들 주셔서 다시 11 개 개의

02-13 23:33:43.500: I/dalvikvm(11215): Debugger is active 
02-13 23:33:43.580: I/System.out(11215): Debugger has connected 
02-13 23:33:43.580: I/System.out(11215): waiting for debugger to settle... 
02-13 23:33:43.781: I/System.out(11215): waiting for debugger to settle... 
02-13 23:33:43.981: I/System.out(11215): waiting for debugger to settle... 
02-13 23:33:44.181: I/System.out(11215): waiting for debugger to settle... 
02-13 23:33:44.381: I/System.out(11215): waiting for debugger to settle... 
02-13 23:33:44.581: I/System.out(11215): waiting for debugger to settle... 
02-13 23:33:44.782: I/System.out(11215): waiting for debugger to settle... 
02-13 23:33:44.982: I/System.out(11215): waiting for debugger to settle... 
02-13 23:33:45.182: I/System.out(11215): waiting for debugger to settle... 
02-13 23:33:45.372: I/System.out(11215): waiting for debugger to settle... 
02-13 23:33:45.582: I/System.out(11215): debugger has settled (1410) 
02-13 23:34:14.651: D/AndroidRuntime(11215): Shutting down VM 
02-13 23:34:14.661: W/dalvikvm(11215): threadid=1: thread exiting with uncaught exception (group=0x4001d5a0) 
02-13 23:34:14.711: E/AndroidRuntime(11215): FATAL EXCEPTION: main 
02-13 23:34:14.711: E/AndroidRuntime(11215): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.johello/com.johello.MainActivity}: java.lang.NullPointerException 
02-13 23:34:14.711: E/AndroidRuntime(11215): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1738) 
02-13 23:34:14.711: E/AndroidRuntime(11215): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1837) 
02-13 23:34:14.711: E/AndroidRuntime(11215): at android.app.ActivityThread.access$1500(ActivityThread.java:132) 
02-13 23:34:14.711: E/AndroidRuntime(11215): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1033) 
02-13 23:34:14.711: E/AndroidRuntime(11215): at android.os.Handler.dispatchMessage(Handler.java:99) 
02-13 23:34:14.711: E/AndroidRuntime(11215): at android.os.Looper.loop(Looper.java:143) 
02-13 23:34:14.711: E/AndroidRuntime(11215): at android.app.ActivityThread.main(ActivityThread.java:4196) 
02-13 23:34:14.711: E/AndroidRuntime(11215): at java.lang.reflect.Method.invokeNative(Native Method) 
02-13 23:34:14.711: E/AndroidRuntime(11215): at java.lang.reflect.Method.invoke(Method.java:507) 
02-13 23:34:14.711: E/AndroidRuntime(11215): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 
02-13 23:34:14.711: E/AndroidRuntime(11215): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 
02-13 23:34:14.711: E/AndroidRuntime(11215): at dalvik.system.NativeStart.main(Native Method) 
02-13 23:34:14.711: E/AndroidRuntime(11215): Caused by: java.lang.NullPointerException 
02-13 23:34:14.711: E/AndroidRuntime(11215): at android.content.ContextWrapper.getResources(ContextWrapper.java:80) 
02-13 23:34:14.711: E/AndroidRuntime(11215): at android.view.View.<init>(View.java:1915) 
02-13 23:34:14.711: E/AndroidRuntime(11215): at android.view.ViewGroup.<init>(ViewGroup.java:299) 
02-13 23:34:14.711: E/AndroidRuntime(11215): at android.widget.LinearLayout.<init>(LinearLayout.java:116) 
02-13 23:34:14.711: E/AndroidRuntime(11215): at com.johello.MainActivity.<init>(MainActivity.java:16) 
02-13 23:34:14.711: E/AndroidRuntime(11215): at java.lang.Class.newInstanceImpl(Native Method) 
02-13 23:34:14.711: E/AndroidRuntime(11215): at java.lang.Class.newInstance(Class.java:1409) 
02-13 23:34:14.711: E/AndroidRuntime(11215): at android.app.Instrumentation.newActivity(Instrumentation.java:1061) 
02-13 23:34:14.711: E/AndroidRuntime(11215): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1730) 
02-13 23:34:14.711: E/AndroidRuntime(11215): ... 11 more 

감사합니다!

Answer 1

NullPointerException 스택 추적은 뷰 작성에 대한 변경으로 인해 발생합니다. 이 같은 전망을 인스턴스화 할 수 없습니다 : onCreate()가 호출 될 때까지 멤버 변수로

public LinearLayout mainWindow = new LinearLayout(this); 
public TextView mainText = new TextView(this); 

는 그들이 필요로하는 Context (당신의 this 포인터) 유효한 자원이 없기 때문에. 뷰에 대한 참조를 클래스 멤버로 선언하려면 괜찮습니다. 하지만 라, onCreate()에 그것들을 초기화 : 당신은 아마 기존의 코드와 함께 수신 된

public class MainActivity extends Activity { 
    public LinearLayout mainWindow; 
    public TextView mainText; 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 

     mainWindow = new LinearLayout(this); 
     mainText = new TextView(this); 

     mainWindow.addView(mainText); 

     setContentView(mainWindow); 
    } 

} 

충돌은 뷰가 부모에게 여러 번 추가 할 수 없으며, 이렇게하면 예외를 던질 것입니다. 예전 코드에서는 내부에서 Handler 내로 동일한 TextView을 두 번 추가하려고 시도했습니다.