When I am trying to fling example this error faced. with java Null pointer exception.
My java code
public class LearnCount extends Activity {
private FlingGallery mGallery;
public boolean onTouchEvent(MotionEvent event) {
return mGallery.onGalleryTouchEvent(event);
}
private String[] teststr = {
"test1","test2","test3","test4","test5"
};
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
setContentView(R.layout.main);
LinearLayout productHolder = (LinearLayout) findViewById(R.id.linearLayoutOfCount);
mGallery = new FlingGallery(this);
mGallery.setAdapter(new ArrayAdapter<String>(getApplicationContext(),
android.R.layout.simple_list_item_1, teststr) {
public View getView(int position, View convertView, ViewGroup parent) {
System.out.println(mGallery.getCurrentPosition() + " position");
if (convertView != null
&& convertView instanceof GalleryViewItem) {
GalleryViewItem galleryView = (GalleryViewItem) convertView;
//galleryView.pImage.setImageResource(mImageIds[position]);
galleryView.b.setText(teststr[position]);
return galleryView;
}
GalleryViewItem gvi = new GalleryViewItem(getApplicationContext(), position);
gvi.b.setText(teststr[position]);
return gvi;
}
});
productHolder.addView(mGallery);
}
public class GalleryViewItem extends TableLayout {
private TextView b;
public GalleryViewItem(Context context, int position) {
super(context);
LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View v = inflater.inflate(R.layout.test, null);
b = (TextView) v.findViewById(R.id.test);
this.addView(v);
}
}
public class FlingGallery extends FrameLayout {
// Constants
private final int swipe_min_distance = 120;
private final int swipe_max_off_path = 250;
private final int swipe_threshold_veloicty = 400;
// Properties
private int mViewPaddingWidth = 0;
private int mAnimationDuration = 250;
private float mSnapBorderRatio = 0.5f;
private boolean mIsGalleryCircular = false;
// Members
private int mGalleryWidth = 0;
private boolean mIsTouched = false;
private boolean mIsDragging = false;
private float mCurrentOffset = 0.0f;
private long mScrollTimestamp = 0;
private int mFlingDirection = 0;
public int mCurrentPosition = 0;
private int mCurrentViewNumber = 0;
private Context mContext;
private Adapter mAdapter;
private FlingGalleryView[] mViews;
private FlingGalleryAnimation mAnimation;
private GestureDetector mGestureDetector;
private Interpolator mDecelerateInterpolater;
public FlingGallery(Context context) {
super(context);
mContext = context;
mAdapter = null;
mViews = new FlingGalleryView[3];
mViews[0] = new FlingGalleryView(0, this);
mViews[1] = new FlingGalleryView(1, this);
mViews[2] = new FlingGalleryView(2, this);
mAnimation = new FlingGalleryAnimation();
mGestureDetector = new GestureDetector(new FlingGestureDetector());
mDecelerateInterpolater = AnimationUtils.loadInterpolator(mContext,
android.R.anim.decelerate_interpolator);
}
public void setPaddingWidth(int viewPaddingWidth) {
mViewPaddingWidth = viewPaddingWidth;
}
public void setAnimationDuration(int animationDuration) {
mAnimationDuration = animationDuration;
}
public void setSnapBorderRatio(float snapBorderRatio) {
mSnapBorderRatio = snapBorderRatio;
}
public int getCurrentPosition() {
return mCurrentPosition;
}
public void setIsGalleryCircular(boolean isGalleryCircular) {
if (mIsGalleryCircular != isGalleryCircular) {
mIsGalleryCircular = isGalleryCircular;
if (mCurrentPosition == getFirstPosition()) {
// We need to reload the view immediately to the left to
// change it to circular view or blank
mViews[getPrevViewNumber(mCurrentViewNumber)]
.recycleView(getPrevPosition(mCurrentPosition));
}
if (mCurrentPosition == getLastPosition()) {
// We need to reload the view immediately to the right to
// change it to circular view or blank
mViews[getNextViewNumber(mCurrentViewNumber)]
.recycleView(getNextPosition(mCurrentPosition));
}
}
}
public int getGalleryCount() {
return (mAdapter == null) ? 0 : mAdapter.getCount();
}
public int getFirstPosition() {
return 0;
}
public int getLastPosition() {
return (getGalleryCount() == 0) ? 0 : getGalleryCount() - 1;
}
private int getPrevPosition(int relativePosition) {
int prevPosition = relativePosition - 1;
if (prevPosition < getFirstPosition()) {
prevPosition = getFirstPosition() - 1;
if (mIsGalleryCircular == true) {
prevPosition = getLastPosition();
}
}
return prevPosition;
}
private int getNextPosition(int relativePosition) {
int nextPosition = relativePosition + 1;
if (nextPosition > getLastPosition()) {
nextPosition = getLastPosition() + 1;
if (mIsGalleryCircular == true) {
nextPosition = getFirstPosition();
}
}
return nextPosition;
}
private int getPrevViewNumber(int relativeViewNumber) {
return (relativeViewNumber == 0) ? 2 : relativeViewNumber - 1;
}
private int getNextViewNumber(int relativeViewNumber) {
return (relativeViewNumber == 2) ? 0 : relativeViewNumber + 1;
}
protected void onLayout(boolean changed, int left, int top, int right,
int bottom) {
super.onLayout(changed, left, top, right, bottom);
// Calculate our view width
mGalleryWidth = right - left;
if (changed == true) {
// Position views at correct starting offsets
mViews[0].setOffset(0, 0, mCurrentViewNumber);
mViews[1].setOffset(0, 0, mCurrentViewNumber);
mViews[2].setOffset(0, 0, mCurrentViewNumber);
}
}
public void setAdapter(Adapter adapter) {
mAdapter = adapter;
mCurrentPosition = 0;
mCurrentViewNumber = 0;
// Load the initial views from adapter
mViews[0].recycleView(mCurrentPosition);
mViews[1].recycleView(getNextPosition(mCurrentPosition));
mViews[2].recycleView(getPrevPosition(mCurrentPosition));
// Position views at correct starting offsets
mViews[0].setOffset(0, 0, mCurrentViewNumber);
mViews[1].setOffset(0, 0, mCurrentViewNumber);
mViews[2].setOffset(0, 0, mCurrentViewNumber);
}
private int getViewOffset(int viewNumber, int relativeViewNumber) {
// Determine width including configured padding width
int offsetWidth = mGalleryWidth + mViewPaddingWidth;
// Position the previous view one measured width to left
if (viewNumber == getPrevViewNumber(relativeViewNumber)) {
return offsetWidth;
}
// Position the next view one measured width to the right
if (viewNumber == getNextViewNumber(relativeViewNumber)) {
return offsetWidth * -1;
}
return 0;
}
void movePrevious() {
// Slide to previous view
mFlingDirection = 1;
processGesture();
}
void moveNext() {
// Slide to next view
mFlingDirection = -1;
processGesture();
}
public boolean onKeyDown(int keyCode, KeyEvent event) {
switch (keyCode) {
case KeyEvent.KEYCODE_DPAD_LEFT:
movePrevious();
return true;
case KeyEvent.KEYCODE_DPAD_RIGHT:
moveNext();
return true;
case KeyEvent.KEYCODE_DPAD_CENTER:
case KeyEvent.KEYCODE_ENTER:
}
return super.onKeyDown(keyCode, event);
}
public boolean onGalleryTouchEvent(MotionEvent event) {
boolean consumed = mGestureDetector.onTouchEvent(event);
if (event.getAction() == MotionEvent.ACTION_UP) {
if (mIsTouched || mIsDragging) {
processScrollSnap();
processGesture();
}
}
return consumed;
}
void processGesture() {
int newViewNumber = mCurrentViewNumber;
int reloadViewNumber = 0;
int reloadPosition = 0;
mIsTouched = false;
mIsDragging = false;
if (mFlingDirection > 0) {
if (mCurrentPosition > getFirstPosition()
|| mIsGalleryCircular == true) {
// Determine previous view and outgoing view to recycle
newViewNumber = getPrevViewNumber(mCurrentViewNumber);
mCurrentPosition = getPrevPosition(mCurrentPosition);
reloadViewNumber = getNextViewNumber(mCurrentViewNumber);
reloadPosition = getPrevPosition(mCurrentPosition);
}
}
if (mFlingDirection < 0) {
if (mCurrentPosition < getLastPosition()
|| mIsGalleryCircular == true) {
// Determine the next view and outgoing view to recycle
newViewNumber = getNextViewNumber(mCurrentViewNumber);
mCurrentPosition = getNextPosition(mCurrentPosition);
reloadViewNumber = getPrevViewNumber(mCurrentViewNumber);
reloadPosition = getNextPosition(mCurrentPosition);
}
}
if (newViewNumber != mCurrentViewNumber) {
mCurrentViewNumber = newViewNumber;
// Reload outgoing view from adapter in new position
mViews[reloadViewNumber].recycleView(reloadPosition);
}
// Ensure input focus on the current view
mViews[mCurrentViewNumber].requestFocus();
// Run the slide animations for view transitions
mAnimation.prepareAnimation(mCurrentViewNumber);
this.startAnimation(mAnimation);
// Reset fling state
mFlingDirection = 0;
//checkNextBackButton(mCurrentPosition);
System.out.println("positionFiling" + mCurrentPosition);
}
void processScrollSnap() {
// Snap to next view if scrolled passed snap position
float rollEdgeWidth = mGalleryWidth * mSnapBorderRatio;
int rollOffset = mGalleryWidth - (int) rollEdgeWidth;
int currentOffset = mViews[mCurrentViewNumber].getCurrentOffset();
if (currentOffset <= rollOffset * -1) {
// Snap to previous view
mFlingDirection = 1;
}
if (currentOffset >= rollOffset) {
// Snap to next view
mFlingDirection = -1;
}
}
public class FlingGalleryView {
private int mViewNumber;
private FrameLayout mParentLayout;
private FrameLayout mInvalidLayout = null;
private LinearLayout mInternalLayout = null;
private View mExternalView = null;
public FlingGalleryView(int viewNumber, FrameLayout parentLayout) {
mViewNumber = viewNumber;
mParentLayout = parentLayout;
// Invalid layout is used when outside gallery
mInvalidLayout = new FrameLayout(mContext);
mInvalidLayout.setLayoutParams(new LinearLayout.LayoutParams(
LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
// Internal layout is permanent for duration
mInternalLayout = new LinearLayout(mContext);
mInternalLayout.setLayoutParams(new LinearLayout.LayoutParams(
LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
mParentLayout.addView(mInternalLayout);
}
public void recycleView(int newPosition) {
if (mExternalView != null) {
mInternalLayout.removeView(mExternalView);
}
if (mAdapter != null) {
if (newPosition >= getFirstPosition()
&& newPosition <= getLastPosition()) {
mExternalView = mAdapter.getView(newPosition,
mExternalView, mInternalLayout);
} else {
mExternalView = mInvalidLayout;
}
}
if (mExternalView != null) {
mInternalLayout.addView(mExternalView,
new LinearLayout.LayoutParams(
LayoutParams.FILL_PARENT,
LayoutParams.FILL_PARENT));
}
}
public void setOffset(int xOffset, int yOffset,
int relativeViewNumber) {
// Scroll the target view relative to its own position relative
// to currently displayed view
mInternalLayout.scrollTo(getViewOffset(mViewNumber,
relativeViewNumber)
+ xOffset, yOffset);
}
public int getCurrentOffset() {
// Return the current scroll position
return mInternalLayout.getScrollX();
}
public void requestFocus() {
mInternalLayout.requestFocus();
}
}
public class FlingGalleryAnimation extends Animation {
private boolean mIsAnimationInProgres;
private int mRelativeViewNumber;
private int mInitialOffset;
private int mTargetOffset;
private int mTargetDistance;
public FlingGalleryAnimation() {
mIsAnimationInProgres = false;
mRelativeViewNumber = 0;
mInitialOffset = 0;
mTargetOffset = 0;
mTargetDistance = 0;
}
public void prepareAnimation(int relativeViewNumber) {
// If we are animating relative to a new view
if (mRelativeViewNumber != relativeViewNumber) {
if (mIsAnimationInProgres == true) {
// We only have three views so if requested again to
// animate in same direction we must snap
int newDirection = (relativeViewNumber == getPrevViewNumber(mRelativeViewNumber)) ? 1
: -1;
int animDirection = (mTargetDistance < 0) ? 1 : -1;
// If animation in same direction
if (animDirection == newDirection) {
// Ran out of time to animate so snap to the target
// offset
mViews[0].setOffset(mTargetOffset, 0,
mRelativeViewNumber);
mViews[1].setOffset(mTargetOffset, 0,
mRelativeViewNumber);
mViews[2].setOffset(mTargetOffset, 0,
mRelativeViewNumber);
}
}
// Set relative view number for animation
mRelativeViewNumber = relativeViewNumber;
}
// Note: In this implementation the targetOffset will always be
// zero
// as we are centering the view; but we include the calculations
// of
// targetOffset and targetDistance for use in future
// implementations
mInitialOffset = mViews[mRelativeViewNumber].getCurrentOffset();
mTargetOffset = getViewOffset(mRelativeViewNumber,
mRelativeViewNumber);
mTargetDistance = mTargetOffset - mInitialOffset;
// Configure base animation properties
this.setDuration(mAnimationDuration);
this.setInterpolator(mDecelerateInterpolater);
// Start/continued animation
mIsAnimationInProgres = true;
}
protected void applyTransformation(float interpolatedTime,
Transformation transformation) {
// Ensure interpolatedTime does not over-shoot then calculate
// new offset
interpolatedTime = (interpolatedTime > 1.0f) ? 1.0f
: interpolatedTime;
int offset = mInitialOffset
+ (int) (mTargetDistance * interpolatedTime);
for (int viewNumber = 0; viewNumber < 3; viewNumber++) {
// Only need to animate the visible views as the other view
// will always be off-screen
if ((mTargetDistance > 0 && viewNumber != getNextViewNumber(mRelativeViewNumber))
|| (mTargetDistance < 0 && viewNumber != getPrevViewNumber(mRelativeViewNumber))) {
mViews[viewNumber].setOffset(offset, 0,
mRelativeViewNumber);
}
}
}
public boolean getTransformation(long currentTime,
Transformation outTransformation) {
if (super.getTransformation(currentTime, outTransformation) == false) {
// Perform final adjustment to offsets to cleanup animation
mViews[0].setOffset(mTargetOffset, 0, mRelativeViewNumber);
mViews[1].setOffset(mTargetOffset, 0, mRelativeViewNumber);
mViews[2].setOffset(mTargetOffset, 0, mRelativeViewNumber);
// Reached the animation target
mIsAnimationInProgres = false;
return false;
}
// Cancel if the screen touched
if (mIsTouched || mIsDragging) {
// Note that at this point we still consider ourselves to be
// animating
// because we have not yet reached the target offset; its
// just that the
// user has temporarily interrupted the animation with a
// touch gesture
return false;
}
return true;
}
}
private class FlingGestureDetector extends GestureDetector.SimpleOnGestureListener {
public boolean onDown(MotionEvent e) {
// Stop animation
mIsTouched = true;
// Reset fling state
mFlingDirection = 0;
return true;
}
public boolean onScroll(MotionEvent e1, MotionEvent e2,
float distanceX, float distanceY) {
if (e2.getAction() == MotionEvent.ACTION_MOVE) {
if (mIsDragging == false) {
// Stop animation
mIsTouched = true;
// Reconfigure scroll
mIsDragging = true;
mFlingDirection = 0;
mScrollTimestamp = System.currentTimeMillis();
mCurrentOffset = mViews[mCurrentViewNumber]
.getCurrentOffset();
}
float maxVelocity = mGalleryWidth
/ (mAnimationDuration / 1000.0f);
long timestampDelta = System.currentTimeMillis()
- mScrollTimestamp;
float maxScrollDelta = maxVelocity
* (timestampDelta / 1000.0f);
float currentScrollDelta = e1.getX() - e2.getX();
if (currentScrollDelta < maxScrollDelta * -1)
currentScrollDelta = maxScrollDelta * -1;
if (currentScrollDelta > maxScrollDelta)
currentScrollDelta = maxScrollDelta;
int scrollOffset = Math.round(mCurrentOffset
+ currentScrollDelta);
// We can't scroll more than the width of our own frame
// layout
if (scrollOffset >= mGalleryWidth)
scrollOffset = mGalleryWidth;
if (scrollOffset <= mGalleryWidth * -1)
scrollOffset = mGalleryWidth * -1;
mViews[0].setOffset(scrollOffset, 0, mCurrentViewNumber);
mViews[1].setOffset(scrollOffset, 0, mCurrentViewNumber);
mViews[2].setOffset(scrollOffset, 0, mCurrentViewNumber);
}
return false;
}
public boolean onFling(MotionEvent e1, MotionEvent e2,
float velocityX, float velocityY) {
if (Math.abs(e1.getY() - e2.getY()) <= swipe_max_off_path) {
if (e2.getX() - e1.getX() > swipe_min_distance
&& Math.abs(velocityX) > swipe_threshold_veloicty) {
movePrevious();
}
if (e1.getX() - e2.getX() > swipe_min_distance
&& Math.abs(velocityX) > swipe_threshold_veloicty) {
moveNext();
}
}
return false;
}
public void onLongPress(MotionEvent e) {
// Finalise scrolling
mFlingDirection = 0;
processGesture();
}
public void onShowPress(MotionEvent e) {
}
public boolean onSingleTapUp(MotionEvent e) {
// Reset fling state
mFlingDirection = 0;
return false;
}
}
}
}
My log cat error message is:
I am the beginner for android, something wrong my code?
Is returning null. Make sure you are referencing the correct id.