How to use isInEditMode() to see layout with custom View in the editor

Question

I must edit a software that have a custom view, when I try to edit layout xml, Eclipse says me:

Use View.isInEditMode() in your custom views to skip code when shown in Eclipse

But I have no idea about how and where I must use isInEditMode() in the app

My xml file is

<?xml version="1.0" encoding="utf-8"?> <LinearLayout       xmlns:android="http://schemas.android.com/apk/res/android"      android:orientation="vertical"      android:layout_width="fill_parent"      android:layout_height="fill_parent"      android:background="#ff000000"     > <TextView      android:id="@+id/result"      android:layout_width="fill_parent"       android:layout_height="wrap_content"      android:gravity="right"      android:textSize="32dip"      android:scrollbars="none"      android:lines="1"      android:freezesText="true"      android:textColor="@color/result"     /> <EditText      android:id="@+id/input"      android:layout_width="fill_parent"      android:layout_height="wrap_content"      android:gravity="left"      android:textSize="28dip"      android:scrollbars="none"      android:singleLine="true"      android:autoText="false"      android:imeOptions="flagNoEnterAction|flagNoExtractUi"      /> <ListView      android:id="@+id/history"      android:layout_width="fill_parent"      android:layout_height="0dip"      android:layout_weight="1"      android:cacheColorHint="#ff000000"      android:choiceMode="singleChoice"      android:scrollbarStyle="outsideInset"      android:scrollbars="none"     /> <calculator.GraphView      android:id="@+id/graph"      android:layout_width="fill_parent"      android:layout_height="0dip"      android:layout_weight="1"      android:visibility="gone"      /> <include layout="@layout/keyboard" /> </LinearLayout> 

And my GraphView is

public class GraphView extends View implements Grapher,         ZoomButtonsController.OnZoomListener,         TouchHandler.TouchHandlerInterface {     private int width, height;     private Matrix matrix = new Matrix();     private Paint paint = new Paint();     private Paint textPaint = new Paint();     private ArrayList<Function> funcs = new ArrayList<Function>();     private Data next = new Data(), endGraph = new Data();     private Data graphs[] = { new Data(), new Data(), new Data(), new Data(),             new Data() };     private static final int GRAPHS_SIZE = 5;     private float gwidth = 8;     private float currentX, currentY;     private float lastMinX;     private Scroller scroller;     private float boundMinY, boundMaxY;     protected ZoomButtonsController zoomController = new ZoomButtonsController(             this);     private ZoomTracker zoomTracker = new ZoomTracker();     private TouchHandler touchHandler;     private float lastTouchX, lastTouchY;      private static final int COL_AXIS = 0xff00a000, COL_GRID = 0xff004000,             COL_TEXT = 0xff00ff00;      private static final int COL_GRAPH[] = { 0xffffffff, 0xff00ffff,             0xffffff00, 0xffff00ff, 0xff80ff80 };      public GraphView(Context context, AttributeSet attrs) {         super(context, attrs);         init(context);     }      public GraphView(Context context) {         super(context);         touchHandler = new TouchHandler(this);         init(context);     }      private void init(Context context) {         zoomController.setOnZoomListener(this);         scroller = new Scroller(context);         paint.setAntiAlias(false);         textPaint.setAntiAlias(true);     }      @SuppressLint("WrongCall")     public String captureScreenshot() {         Bitmap bitmap = Bitmap.createBitmap(width, height,                 Bitmap.Config.RGB_565);         Canvas canvas = new Canvas(bitmap);         onDraw(canvas);         return Util.saveBitmap(bitmap, Grapher.SCREENSHOT_DIR, "calculator");     }      private void clearAllGraph() {         for (int i = 0; i < GRAPHS_SIZE; ++i) {             graphs[i].clear();         }     }      public void setFunctions(ArrayList<Function> fs) {         funcs.clear();         for (Function f : fs) {             int arity = f.arity();             if (arity == 0 || arity == 1) {                 funcs.add(f);             }         }         clearAllGraph();         invalidate();     }      public void setFunction(Function f) {         funcs.clear();         if (f != null) {             funcs.add(f);         }         clearAllGraph();         invalidate();     }      public void onVisibilityChanged(boolean visible) {     }      public void onZoom(boolean zoomIn) {         if (zoomIn) {             if (canZoomIn()) {                 gwidth /= 2;                 invalidateGraphs();             }         } else {             if (canZoomOut()) {                 gwidth *= 2;                 invalidateGraphs();             }         }         zoomController.setZoomInEnabled(canZoomIn());         zoomController.setZoomOutEnabled(canZoomOut());     }      public void onResume() {     }      public void onPause() {     }      public void onDetachedFromWindow() {         zoomController.setVisible(false);         super.onDetachedFromWindow();     }      protected void onSizeChanged(int w, int h, int ow, int oh) {         width = w;         height = h;         clearAllGraph();     }      protected void onDraw(Canvas canvas) {         if (funcs.size() == 0) {             return;         }         if (scroller.computeScrollOffset()) {             final float scale = gwidth / width;             currentX = scroller.getCurrX() * scale;             currentY = scroller.getCurrY() * scale;             if (!scroller.isFinished()) {                 invalidate();             }         }         drawGraph(canvas);     }      private float eval(Function f, float x) {         float v = (float) f.eval(x);          if (v < -10000f) {             return -10000f;         }         if (v > 10000f) {             return 10000f;         }         return v;     }      private float distance2(float x1, float y1, float x2, float y2, float y) {         final float dx = x2 - x1;         final float dy = y2 - y1;         final float up = dx * (y1 + y2 - y - y);         return up * up / (dx * dx + dy * dy);     }      private void computeGraph(Function f, float minX, float maxX, float minY,             float maxY, Data graph) {         if (f.arity() == 0) {             float v = (float) f.eval();             if (v < -10000f) {                 v = -10000f;             }             if (v > 10000f) {                 v = 10000f;             }             graph.clear();             graph.push(minX, v);             graph.push(maxX, v);             return;         }          final float scale = width / gwidth;         final float maxStep = 15.8976f / scale;         final float minStep = .05f / scale;         float ythresh = 1 / scale;         ythresh = ythresh * ythresh;         if (!graph.empty()) {             if (minX >= lastMinX) {                 graph.eraseBefore(minX);             } else {                 graph.eraseAfter(maxX);                 maxX = Math.min(maxX, graph.firstX());                 graph.swap(endGraph);             }         }         if (graph.empty()) {             graph.push(minX, eval(f, minX));         }         float leftX, leftY;         float rightX = graph.topX(), rightY = graph.topY();         int nEval = 1;         while (true) {             leftX = rightX;             leftY = rightY;             if (leftX > maxX) {                 break;             }             if (next.empty()) {                 float x = leftX + maxStep;                 next.push(x, eval(f, x));                 ++nEval;             }             rightX = next.topX();             rightY = next.topY();             next.pop();              if (leftY != leftY && rightY != rightY) { // NaN                 continue;             }              float dx = rightX - leftX;             float middleX = (leftX + rightX) / 2;             float middleY = eval(f, middleX);             ++nEval;             boolean middleIsOutside = (middleY < leftY && middleY < rightY)                     || (leftY < middleY && rightY < middleY);             if (dx < minStep) {                 if (middleIsOutside) {                     graph.push(rightX, Float.NaN);                 }                 graph.push(rightX, rightY);                 continue;             }             if (middleIsOutside                     && ((leftY < minY && rightY > maxY) || (leftY > maxY && rightY < minY))) {                 graph.push(rightX, Float.NaN);                 graph.push(rightX, rightY);                 continue;             }              if (!middleIsOutside) {                  if (distance2(leftX, leftY, rightX, rightY, middleY) < ythresh) {                     graph.push(rightX, rightY);                     continue;                 }             }             next.push(rightX, rightY);             next.push(middleX, middleY);             rightX = leftX;             rightY = leftY;         }         if (!endGraph.empty()) {             graph.append(endGraph);         }         long t2 = System.currentTimeMillis();          next.clear();         endGraph.clear();     }      private static Path path = new Path();      private Path graphToPath(Data graph) {         boolean first = true;         int size = graph.size;         float[] xs = graph.xs;         float[] ys = graph.ys;         path.rewind();         for (int i = 0; i < size; ++i) {             float y = ys[i];             float x = xs[i];             // Calculator.log("path " + x + ' ' + y);             if (y == y) { // !NaN                 if (first) {                     path.moveTo(x, y);                     first = false;                 } else {                     path.lineTo(x, y);                 }             } else {                 first = true;             }         }         return path;     }      private static final float NTICKS = 15;      private static float stepFactor(float w) {         float f = 1;         while (w / f > NTICKS) {             f *= 10;         }         while (w / f < NTICKS / 10) {             f /= 10;         }         float r = w / f;         if (r < NTICKS / 5) {             return f / 5;         } else if (r < NTICKS / 2) {             return f / 2;         } else {             return f;         }     }      private static StringBuilder b = new StringBuilder();     private static char[] buf = new char[20];      private static StringBuilder format(float fv) {         int pos = 0;         boolean addDot = false;         int v = Math.round(fv * 100);         boolean isNeg = v < 0;         v = isNeg ? -v : v;         for (int i = 0; i < 2; ++i) {             int digit = v % 10;             v /= 10;             if (digit != 0 || addDot) {                 buf[pos++] = (char) ('0' + digit);                 addDot = true;             }         }         if (addDot) {             buf[pos++] = '.';         }         if (v == 0) {             buf[pos++] = '0';         }         while (v != 0) {             buf[pos++] = (char) ('0' + (v % 10));             v /= 10;         }         if (isNeg) {             buf[pos++] = '-';         }         b.setLength(0);         b.append(buf, 0, pos);         b.reverse();         return b;     }      private void drawGraph(Canvas canvas) {         long t1 = System.currentTimeMillis();         float minX = currentX - gwidth / 2;         float maxX = minX + gwidth;         float ywidth = gwidth * height / width;         float minY = currentY - ywidth / 2;         float maxY = minY + ywidth;         if (minY < boundMinY || maxY > boundMaxY) {             float halfw = ywidth / 2;             boundMinY = minY - halfw;             boundMaxY = maxY + halfw;             clearAllGraph();         }          canvas.drawColor(0xff000000);          paint.setStrokeWidth(0);         paint.setAntiAlias(false);         paint.setStyle(Paint.Style.STROKE);          final float h2 = height / 2f;         final float scale = width / gwidth;          float x0 = -minX * scale;         boolean drawYAxis = true;         if (x0 < 25) {             x0 = 25;             // drawYAxis = false;         } else if (x0 > width - 3) {             x0 = width - 3;             // drawYAxis = false;         }         float y0 = maxY * scale;         if (y0 < 3) {             y0 = 3;         } else if (y0 > height - 15) {             y0 = height - 15;         }          final float tickSize = 3;         final float y2 = y0 + tickSize;         paint.setColor(COL_GRID);         float step = stepFactor(gwidth);         float v = ((int) (minX / step)) * step;         textPaint.setColor(COL_TEXT);         textPaint.setTextSize(12);         textPaint.setTextAlign(Paint.Align.CENTER);         float stepScale = step * scale;         for (float x = (v - minX) * scale; x <= width; x += stepScale, v += step) {             canvas.drawLine(x, 0, x, height, paint);             if (!(-.001f < v && v < .001f)) {                 StringBuilder b = format(v);                 canvas.drawText(b, 0, b.length(), x, y2 + 10, textPaint);             }         }          final float x1 = x0 - tickSize;         v = ((int) (minY / step)) * step;         textPaint.setTextAlign(Paint.Align.RIGHT);         for (float y = height - (v - minY) * scale; y >= 0; y -= stepScale, v += step) {             canvas.drawLine(0, y, width, y, paint);             if (!(-.001f < v && v < .001f)) {                 StringBuilder b = format(v);                 canvas.drawText(b, 0, b.length(), x1, y + 4, textPaint);             }         }          paint.setColor(COL_AXIS);         if (drawYAxis) {             canvas.drawLine(x0, 0, x0, height, paint);         }         canvas.drawLine(0, y0, width, y0, paint);          matrix.reset();         matrix.preTranslate(-currentX, -currentY);         matrix.postScale(scale, -scale);         matrix.postTranslate(width / 2, height / 2);          paint.setStrokeWidth(0);         paint.setAntiAlias(false);          int n = Math.min(funcs.size(), GRAPHS_SIZE);         for (int i = 0; i < n; ++i) {             computeGraph(funcs.get(i), minX, maxX, boundMinY, boundMaxY,                     graphs[i]);             Path path = graphToPath(graphs[i]);             path.transform(matrix);             paint.setColor(COL_GRAPH[i]);             canvas.drawPath(path, paint);         }         lastMinX = minX;     }      private boolean canZoomIn() {         return gwidth > 1f;     }      private boolean canZoomOut() {         return gwidth < 50;     }      private void invalidateGraphs() {         clearAllGraph();         boundMinY = boundMaxY = 0;         invalidate();     }      @Override     public boolean onTouchEvent(MotionEvent event) {         return touchHandler != null ? touchHandler.onTouchEvent(event) : super                 .onTouchEvent(event);     }      public void onTouchDown(float x, float y) {         zoomController.setVisible(true);         if (!scroller.isFinished()) {             scroller.abortAnimation();         }         lastTouchX = x;         lastTouchY = y;     }      public void onTouchMove(float x, float y) {         float deltaX = x - lastTouchX;         float deltaY = y - lastTouchY;         if (deltaX < -1 || deltaX > 1 || deltaY < -1 || deltaY > 1) {             scroll(-deltaX, deltaY);             lastTouchX = x;             lastTouchY = y;             invalidate();         }     }      public void onTouchUp(float x, float y) {         final float scale = width / gwidth;         float sx = -touchHandler.velocityTracker.getXVelocity();         float sy = touchHandler.velocityTracker.getYVelocity();         final float asx = Math.abs(sx);         final float asy = Math.abs(sy);         if (asx < asy / 3) {             sx = 0;         } else if (asy < asx / 3) {             sy = 0;         }         scroller.fling(Math.round(currentX * scale),                 Math.round(currentY * scale), Math.round(sx), Math.round(sy),                 -10000, 10000, -10000, 10000);         invalidate();     }      public void onTouchZoomDown(float x1, float y1, float x2, float y2) {         zoomTracker.start(gwidth, x1, y1, x2, y2);     }      public void onTouchZoomMove(float x1, float y1, float x2, float y2) {         if (!zoomTracker.update(x1, y1, x2, y2)) {             return;         }         float targetGwidth = zoomTracker.value;         if (targetGwidth > .25f && targetGwidth < 200) {             gwidth = targetGwidth;         }         invalidateGraphs();     }      private void scroll(float deltaX, float deltaY) {         final float scale = gwidth / width;         float dx = deltaX * scale;         float dy = deltaY * scale;         final float adx = Math.abs(dx);         final float ady = Math.abs(dy);         if (adx < ady / 3) {             dx = 0;         } else if (ady < adx / 3) {             dy = 0;         }         currentX += dx;         currentY += dy;     } } 

The error Log of the XML editor

java.lang.NullPointerException     at android.widget.ZoomButtonsController.createContainer(ZoomButtonsController.java:266)     at android.widget.ZoomButtonsController.<init>(ZoomButtonsController.java:212)     at calculator.GraphView.<init>(GraphView.java:43)     at sun.reflect.NativeConstructorAccessorImpl.newInstance0(    at sun.reflect.NativeConstructorAccessorImpl.newInstance(    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(    at java.lang.reflect.Constructor.newInstance(    at com.android.ide.eclipse.adt.internal.editors.layout.ProjectCallback.instantiateClass(ProjectCallback.java:422)     at com.android.ide.eclipse.adt.internal.editors.layout.ProjectCallback.loadView(ProjectCallback.java:179)     at android.view.BridgeInflater.loadCustomView(BridgeInflater.java:207)     at android.view.BridgeInflater.createViewFromTag(BridgeInflater.java:135)     at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:746)     at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:64)     at android.view.LayoutInflater.rInflate(LayoutInflater.java:718)     at android.view.LayoutInflater.inflate(LayoutInflater.java:489)     at android.view.LayoutInflater.inflate(LayoutInflater.java:372) 

Answer 1

isInEditMode()should be used inside the Custom View constructor. Try the following code:

     public class GraphView extends View implements Grapher         {           public GraphView(Context context, AttributeSet attrs) {                 super(context, attrs);                 if(!isInEditMode())                  init(context);             }              public GraphView(Context context) {                 super(context);                if(!isInEditMode()){                 touchHandler = new TouchHandler(this);                 init(context);               }             } 

Answer 2

public class CustomTextView extends TextView {  public CustomTextView(Context context) {     super(context); }  public CustomTextView(Context context, AttributeSet attrs) {     super(context, attrs);      if (!isInEditMode()) {         createTypeface(context, attrs); //whatever added functionality you are trying to add to Widget, call that inside this condition.      }  }  public CustomTextView(Context context, AttributeSet attrs, int defStyle) {     super(context, attrs, defStyle); }   //Typeface I wan to set to my Custom TextView It can be any other functionality of your choice  private void createTypeface(Context context, AttributeSet attrs) {      TypedArray styledAttrs = context.obtainStyledAttributes(attrs,             R.styleable.CustomTextView);     String fontName = styledAttrs             .getString(R.styleable.CustomTextView_Typeface);     styledAttrs.recycle();      if (fontName != null) {         Typeface typeface = Typeface.createFromAsset(context.getAssets(),                 "fonts/" + fontName);          setTypeface(typeface);         styledAttrs.recycle();     } }  }