XY-Pad X 및 Y NPE 오류 가져 오기 (해결 된)

Question

최근에 설정보기에서 사용자 입력의 X 및 Y 좌표를 표시하는 간단한 XY 패드 인 안드로이드 응용 프로그램 용 프로그램을 작업하고 있습니다. 그것이 작동하는 방식은 두 개의 TextViews (하나는 X 값을 표시하고 하나는 Y 값을 표시하는)가있는 응용 프로그램 용 XML 레이아웃이며 XY- 패드가있는 뷰도 있습니다. 내가 계속 실행중인 문제는 XML의 연결된 클래스 파일에 X 및 Y 좌표를 보내어 TextViews의 텍스트를 설정하려고하면 오류가 발생합니다 (NullPointerException 오류). 누구든지 코드에 의해 잘못 될 수있는 것을 알고 있습니까?

public class drawing extends View{ 

    private Paint paint = new Paint(); 
    private Path path = new Path(); 

    private float eventX = 0; 
    private float eventY = 0; 

    public drawing(Context context, AttributeSet attrs) { 
    super(context, attrs); 
    paint.setAntiAlias(true); 
    paint.setStrokeWidth(20f); 
    paint.setColor(Color.YELLOW); 
    paint.setStyle(Paint.Style.STROKE); 
    paint.setStrokeJoin(Paint.Join.ROUND); 
    } 

    @SuppressLint("DrawAllocation") 
@Override 
    protected void onDraw(Canvas canvas) { 
    canvas.drawPath(path, paint); 
    try{    
     Start itUp = new Start(); 
     itUp.setXY(eventX, eventY); //The call to the method that is being problematic 
     } 
     catch(Exception e1){ 
      Toast.makeText(drawing.this.getContext(), "We have an error! "+ e1, Toast.LENGTH_LONG).show(); 
     } 
    } 


    @Override 
    public boolean onTouchEvent(MotionEvent event) { 
    try{   
    eventX = event.getX(); 
    eventY = event.getY(); 

    switch (event.getAction()) { 
    case MotionEvent.ACTION_DOWN:   
     path.moveTo(eventX, eventY); 
     return true; 
    case MotionEvent.ACTION_MOVE: 
     path.reset(); 
     path.addCircle(eventX, eventY, 20, Path.Direction.CW); 
     break; 
    case MotionEvent.ACTION_UP: 
     path.reset(); 
     break; 
     default: 
      path.reset(); 
     return false; 
    } 
    // Schedules a repaint. 
    invalidate(); 
    return true; 

    } 
    catch(Exception e1){ 
     return true; 
    } 
    } 


} 

:

<RelativeLayout 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" 

tools:context=".Start" > 

<TextView 
    android:id="@+id/theX" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:text="X:" 
    android:textAppearance="?android:attr/textAppearanceMedium" /> 

<TextView 
    android:id="@+id/theY" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_above="@+id/button1" 
    android:layout_marginBottom="30dp" 
    android:layout_toLeftOf="@+id/linearLayout1" 
    android:text="Y: " 
    android:textAppearance="?android:attr/textAppearanceMedium" /> 

<view class="com.example.robotcontroller.drawing" 
    android:id="@+id/XYpad" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_centerVertical="true" 
    android:layout_toRightOf="@+id/button1" /> 

여기

가이 XML 데이터의보기의 내부에 간다 인 '그리기'클래스입니다 : 여기

는 XML 데이터입니다 보기가 잘 표시되고 손가락을 추적 할 수 있으며 문제없이 다른 클래스의 다른 메소드를 호출 할 수 있습니다. 문제는 XML에서 두 개의 TextView를 조작하는 TextView 객체를 만들려고 할 때 프로그램이 충돌하고 'NullPointerException'이 발생합니다. 항목이 존재하고 텍스트가 포함 된 이유를 이해하지 못합니다. 이유는 무엇입니까? 그것이 존재하지 않겠는가? 여기

public class Start extends Activity { 


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

@Override 
public boolean onCreateOptionsMenu(Menu menu) { 
    // Inflate the menu; this adds items to the action bar if it is present. 
    getMenuInflater().inflate(R.menu.start, menu); 
    return true; 
} 


public void setXY(float x, float y){ //The method where the TextViews are created, and pointing to null objects.... 
    TextView tv1 = (TextView) findViewById(R.id.theX); 
    TextView tv2 = (TextView) findViewById(R.id.theY); 
    tv1.setText("X value: "+x);  
    tv2.setText("Y value: "+y); 
} 




} 

가 NPE 스택 트레이스 (...이 도움이되기를 바랍니다)입니다 :

다음

이 문제가되고있는 'setXY'방법을 포함 무엇인가 '시작'활동

at android.widget.Toast.show(Toast.java:113) 
at com.example.robotcontroller.drawing.onDraw(drawing.java:44) 
at android.view.View.draw(View.java:14433) 
at android.view.View.draw(View.java:14318) 
at android.view.ViewGroup.drawChild(ViewGroup.java:3103) 
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2940) 
at android.view.View.draw(View.java:14316) 
at android.view.ViewGroup.drawChild(ViewGroup.java:3103) 
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2940) 
at android.view.View.draw(View.java:14316) 
at android.view.ViewGroup.drawChild(ViewGroup.java:3103) 
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2940) 
at android.view.View.draw(View.java:14436) 
at android.view.View.draw(View.java:14318) 
at android.view.ViewGroup.drawChild(ViewGroup.java:3103) 
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2940) 
at android.view.View.draw(View.java:14436) 
at com.android.layoutlib.bridge.impl.RenderSessionImpl.render(RenderSessionImpl.java:584) 
at com.android.layoutlib.bridge.Bridge.createSession(Bridge.java:338) 
at com.android.ide.common.rendering.LayoutLibrary.createSession(LayoutLibrary.java:334) 
at com.android.ide.eclipse.adt.internal.editors.layout.gle2.RenderService.createRenderSession(RenderService.java:451) 
at com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.renderWithBridge(GraphicalEditorPart.java:1545) 
at com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.recomputeLayout(GraphicalEditorPart.java:1302) 
at com.android.ide.eclipse.adt.internal.editors.layout.gle2.GraphicalEditorPart.activated(GraphicalEditorPart.java:1059) 
at com.android.ide.eclipse.adt.internal.editors.layout.LayoutEditorDelegate.delegateActivated(LayoutEditorDelegate.java:743) 
at com.android.ide.eclipse.adt.internal.editors.common.CommonXmlEditor.activated(CommonXmlEditor.java:416) 
at com.android.ide.eclipse.adt.internal.editors.layout.gle2.LayoutWindowCoordinator.partActivated(LayoutWindowCoordinator.java:379) 
at org.eclipse.ui.internal.PartService$6.run(PartService.java:131) 
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42) 
at org.eclipse.ui.internal.PartService.partActivated(PartService.java:129) 
at org.eclipse.ui.internal.WorkbenchPage$12.run(WorkbenchPage.java:4462) 
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42) 
at org.eclipse.ui.internal.WorkbenchPage.firePartActivated(WorkbenchPage.java:4460) 
at org.eclipse.ui.internal.WorkbenchPage.access$16(WorkbenchPage.java:4440) 
at org.eclipse.ui.internal.WorkbenchPage$E4PartListener.partActivated(WorkbenchPage.java:173) 
at org.eclipse.e4.ui.internal.workbench.PartServiceImpl$2.run(PartServiceImpl.java:193) 
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42) 
at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.firePartActivated(PartServiceImpl.java:191) 
at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.activate(PartServiceImpl.java:596) 
at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.activate(PartServiceImpl.java:549) 
at org.eclipse.e4.ui.internal.workbench.swt.AbstractPartRenderer.activate(AbstractPartRenderer.java:105) 
at org.eclipse.e4.ui.workbench.renderers.swt.StackRenderer$ActivationJob.run(StackRenderer.java:214) 
at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35) 
at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:135) 
at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:4144) 
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3761) 
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$9.run(PartRenderingEngine.java:1053) 
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332) 
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:942) 
at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:86) 
at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:588) 
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332) 
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:543) 
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149) 
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:124) 
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196) 
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110) 
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79) 
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:353) 
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:180) 
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) 
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) 
at java.lang.reflect.Method.invoke(Unknown Source) 
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:629) 
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:584) 
at org.eclipse.equinox.launcher.Main.run(Main.java:1438) 
at org.eclipse.equinox.launcher.Main.main(Main.java:1414) 

Answer 1

마침내 TextView를 업데이트하는 방법을 알아 냈습니다. 내가 한 방법은 그렇게 같은 드로잉 클래스에 두 개의 텍스트 뷰 객체를 생성하여이었다.

  TextView v1 = (TextView) this.getRootView().findViewById(R.id.textView1); 
     TextView v2 = (TextView) this.getRootView().findViewById(R.id.textView2); 

로 getRootView 키워드가 난 일부 데이터는 도면에서였다보기에서 개체를 얻을 필요가 있었는지 나는 프로그램을 만든 X 및 Y TextViews를 다음과 같이 설정하여 값을 업데이트하십시오.

protected void onDraw(Canvas canvas) { 
    canvas.drawPath(path, paint); 
    try{    
     TextView v1 = (TextView) this.getRootView().findViewById(R.id.textView1); 
     TextView v2 = (TextView) this.getRootView().findViewById(R.id.textView2); 
     v1.setText("X: "+eventX); 
     v2.setText("Y: "+eventY); 
     } 
     catch(Exception e1){ 
      Log.d("myError", e1); 
     } 
    }