# Scroller
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
Summary:[Ctors](https://developer.android.com/reference/android/widget/Scroller#pubctors)\|[Methods](https://developer.android.com/reference/android/widget/Scroller#pubmethods)\|[Inherited Methods](https://developer.android.com/reference/android/widget/Scroller#inhmethods)
# Scroller
*** ** * ** ***
[Kotlin](https://developer.android.com/reference/kotlin/android/widget/Scroller "View this page in Kotlin")\|Java
`
public
class
Scroller
`
`
extends `[Object](https://developer.android.com/reference/java/lang/Object)`
``
`
|---|-------------------------|
| [java.lang.Object](https://developer.android.com/reference/java/lang/Object) ||
| ↳ | android.widget.Scroller |
*** ** * ** ***
This class encapsulates scrolling. You can use scrollers ([Scroller](https://developer.android.com/reference/android/widget/Scroller)or[OverScroller](https://developer.android.com/reference/android/widget/OverScroller)) to collect the data you need to produce a scrolling animation---for example, in response to a fling gesture. Scrollers track scroll offsets for you over time, but they don't automatically apply those positions to your view. It's your responsibility to get and apply new coordinates at a rate that will make the scrolling animation look smooth.
Here is a simple example:
```
private Scroller mScroller = new Scroller(context);
...
public void zoomIn() {
// Revert any animation currently in progress
mScroller.forceFinished(true);
// Start scrolling by providing a starting point and
// the distance to travel
mScroller.startScroll(0, 0, 100, 0);
// Invalidate to request a redraw
invalidate();
}
```
To track the changing positions of the x/y coordinates, use[computeScrollOffset()](https://developer.android.com/reference/android/widget/Scroller#computeScrollOffset()). The method returns a boolean to indicate whether the scroller is finished. If it isn't, it means that a fling or programmatic pan operation is still in progress. You can use this method to find the current offsets of the x and y coordinates, for example:
```
if (mScroller.computeScrollOffset()) {
// Get current x and y positions
int currX = mScroller.getCurrX();
int currY = mScroller.getCurrY();
...
}
```
## Summary
| ### Public constructors ||
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---|
| ` `[Scroller](https://developer.android.com/reference/android/widget/Scroller#Scroller(android.content.Context))`(`[Context](https://developer.android.com/reference/android/content/Context)` context) ` Create a Scroller with the default duration and interpolator. |
| ` `[Scroller](https://developer.android.com/reference/android/widget/Scroller#Scroller(android.content.Context,%20android.view.animation.Interpolator))`(`[Context](https://developer.android.com/reference/android/content/Context)` context, `[Interpolator](https://developer.android.com/reference/android/view/animation/Interpolator)` interpolator) ` Create a Scroller with the specified interpolator. |
| ` `[Scroller](https://developer.android.com/reference/android/widget/Scroller#Scroller(android.content.Context,%20android.view.animation.Interpolator,%20boolean))`(`[Context](https://developer.android.com/reference/android/content/Context)` context, `[Interpolator](https://developer.android.com/reference/android/view/animation/Interpolator)` interpolator, boolean flywheel) ` Create a Scroller with the specified interpolator. |
| ### Public methods ||
|------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| ` void` | ` `[abortAnimation](https://developer.android.com/reference/android/widget/Scroller#abortAnimation())`() ` Stops the animation. |
| ` boolean` | ` `[computeScrollOffset](https://developer.android.com/reference/android/widget/Scroller#computeScrollOffset())`() ` Call this when you want to know the new location. |
| ` void` | ` `[extendDuration](https://developer.android.com/reference/android/widget/Scroller#extendDuration(int))`(int extend) ` Extend the scroll animation. |
| ` void` | ` `[fling](https://developer.android.com/reference/android/widget/Scroller#fling(int,%20int,%20int,%20int,%20int,%20int,%20int,%20int))`(int startX, int startY, int velocityX, int velocityY, int minX, int maxX, int minY, int maxY) ` Start scrolling based on a fling gesture. |
| ` final void` | ` `[forceFinished](https://developer.android.com/reference/android/widget/Scroller#forceFinished(boolean))`(boolean finished) ` Force the finished field to a particular value. |
| ` float` | ` `[getCurrVelocity](https://developer.android.com/reference/android/widget/Scroller#getCurrVelocity())`() ` Returns the current velocity. |
| ` final int` | ` `[getCurrX](https://developer.android.com/reference/android/widget/Scroller#getCurrX())`() ` Returns the current X offset in the scroll. |
| ` final int` | ` `[getCurrY](https://developer.android.com/reference/android/widget/Scroller#getCurrY())`() ` Returns the current Y offset in the scroll. |
| ` final int` | ` `[getDuration](https://developer.android.com/reference/android/widget/Scroller#getDuration())`() ` Returns how long the scroll event will take, in milliseconds. |
| ` final int` | ` `[getFinalX](https://developer.android.com/reference/android/widget/Scroller#getFinalX())`() ` Returns where the scroll will end. |
| ` final int` | ` `[getFinalY](https://developer.android.com/reference/android/widget/Scroller#getFinalY())`() ` Returns where the scroll will end. |
| ` final int` | ` `[getStartX](https://developer.android.com/reference/android/widget/Scroller#getStartX())`() ` Returns the start X offset in the scroll. |
| ` final int` | ` `[getStartY](https://developer.android.com/reference/android/widget/Scroller#getStartY())`() ` Returns the start Y offset in the scroll. |
| ` final boolean` | ` `[isFinished](https://developer.android.com/reference/android/widget/Scroller#isFinished())`() ` Returns whether the scroller has finished scrolling. |
| ` void` | ` `[setFinalX](https://developer.android.com/reference/android/widget/Scroller#setFinalX(int))`(int newX) ` Sets the final position (X) for this scroller. |
| ` void` | ` `[setFinalY](https://developer.android.com/reference/android/widget/Scroller#setFinalY(int))`(int newY) ` Sets the final position (Y) for this scroller. |
| ` final void` | ` `[setFriction](https://developer.android.com/reference/android/widget/Scroller#setFriction(float))`(float friction) ` The amount of friction applied to flings. |
| ` void` | ` `[startScroll](https://developer.android.com/reference/android/widget/Scroller#startScroll(int,%20int,%20int,%20int,%20int))`(int startX, int startY, int dx, int dy, int duration) ` Start scrolling by providing a starting point, the distance to travel, and the duration of the scroll. |
| ` void` | ` `[startScroll](https://developer.android.com/reference/android/widget/Scroller#startScroll(int,%20int,%20int,%20int))`(int startX, int startY, int dx, int dy) ` Start scrolling by providing a starting point and the distance to travel. |
| ` int` | ` `[timePassed](https://developer.android.com/reference/android/widget/Scroller#timePassed())`() ` Returns the time elapsed since the beginning of the scrolling. |
| ### Inherited methods |
|-----------------------|---|
| From class` `[java.lang.Object](https://developer.android.com/reference/java/lang/Object)` ` |--------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | ` `[Object](https://developer.android.com/reference/java/lang/Object) | ` `[clone](https://developer.android.com/reference/java/lang/Object#clone())`() ` Creates and returns a copy of this object. | | ` boolean` | ` `[equals](https://developer.android.com/reference/java/lang/Object#equals(java.lang.Object))`(`[Object](https://developer.android.com/reference/java/lang/Object)` obj) ` Indicates whether some other object is "equal to" this one. | | ` void` | ` `[finalize](https://developer.android.com/reference/java/lang/Object#finalize())`() ` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. | | ` final `[Class](https://developer.android.com/reference/java/lang/Class)`` | ` `[getClass](https://developer.android.com/reference/java/lang/Object#getClass())`() ` Returns the runtime class of this`Object`. | | ` int` | ` `[hashCode](https://developer.android.com/reference/java/lang/Object#hashCode())`() ` Returns a hash code value for the object. | | ` final void` | ` `[notify](https://developer.android.com/reference/java/lang/Object#notify())`() ` Wakes up a single thread that is waiting on this object's monitor. | | ` final void` | ` `[notifyAll](https://developer.android.com/reference/java/lang/Object#notifyAll())`() ` Wakes up all threads that are waiting on this object's monitor. | | ` `[String](https://developer.android.com/reference/java/lang/String) | ` `[toString](https://developer.android.com/reference/java/lang/Object#toString())`() ` Returns a string representation of the object. | | ` final void` | ` `[wait](https://developer.android.com/reference/java/lang/Object#wait(long,%20int))`(long timeoutMillis, int nanos) ` Causes the current thread to wait until it is awakened, typically by being*notified* or*interrupted*, or until a certain amount of real time has elapsed. | | ` final void` | ` `[wait](https://developer.android.com/reference/java/lang/Object#wait(long))`(long timeoutMillis) ` Causes the current thread to wait until it is awakened, typically by being*notified* or*interrupted*, or until a certain amount of real time has elapsed. | | ` final void` | ` `[wait](https://developer.android.com/reference/java/lang/Object#wait())`() ` Causes the current thread to wait until it is awakened, typically by being*notified* or*interrupted*. | ||
## Public constructors
### Scroller
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public Scroller (Context context)
```
Create a Scroller with the default duration and interpolator.
| Parameters ||
|-----------|------------------|
| `context` | `Context`
|
### Scroller
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public Scroller (Context context,
Interpolator interpolator)
```
Create a Scroller with the specified interpolator. If the interpolator is null, the default (viscous) interpolator will be used. "Flywheel" behavior will be in effect for apps targeting Honeycomb or newer.
| Parameters ||
|----------------|-----------------------|
| `context` | `Context`
|
| `interpolator` | `Interpolator`
|
### Scroller
Added in[API level 11](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public Scroller (Context context,
Interpolator interpolator,
boolean flywheel)
```
Create a Scroller with the specified interpolator. If the interpolator is null, the default (viscous) interpolator will be used. Specify whether or not to support progressive "flywheel" behavior in flinging.
| Parameters ||
|----------------|-----------------------|
| `context` | `Context`
|
| `interpolator` | `Interpolator`
|
| `flywheel` | `boolean`
|
## Public methods
### abortAnimation
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void abortAnimation ()
```
Stops the animation. Contrary to[forceFinished(boolean)](https://developer.android.com/reference/android/widget/Scroller#forceFinished(boolean)), aborting the animating cause the scroller to move to the final x and y position
**See also:**
- [forceFinished(boolean)](https://developer.android.com/reference/android/widget/Scroller#forceFinished(boolean))
### computeScrollOffset
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public boolean computeScrollOffset ()
```
Call this when you want to know the new location. If it returns true, the animation is not yet finished.
| Returns ||
|-----------|--------|
| `boolean` |
|
### extendDuration
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void extendDuration (int extend)
```
Extend the scroll animation. This allows a running animation to scroll further and longer, when used with[setFinalX(int)](https://developer.android.com/reference/android/widget/Scroller#setFinalX(int))or[setFinalY(int)](https://developer.android.com/reference/android/widget/Scroller#setFinalY(int)).
| Parameters ||
|----------|----------------------------------------------------------|
| `extend` | `int`: Additional time to scroll in milliseconds.
|
**See also:**
- [setFinalX(int)](https://developer.android.com/reference/android/widget/Scroller#setFinalX(int))
- [setFinalY(int)](https://developer.android.com/reference/android/widget/Scroller#setFinalY(int))
### fling
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void fling (int startX,
int startY,
int velocityX,
int velocityY,
int minX,
int maxX,
int minY,
int maxY)
```
Start scrolling based on a fling gesture. The distance travelled will depend on the initial velocity of the fling.
| Parameters ||
|-------------|--------------------------------------------------------------------------------|
| `startX` | `int`: Starting point of the scroll (X)
|
| `startY` | `int`: Starting point of the scroll (Y)
|
| `velocityX` | `int`: Initial velocity of the fling (X) measured in pixels per second.
|
| `velocityY` | `int`: Initial velocity of the fling (Y) measured in pixels per second
|
| `minX` | `int`: Minimum X value. The scroller will not scroll past this point.
|
| `maxX` | `int`: Maximum X value. The scroller will not scroll past this point.
|
| `minY` | `int`: Minimum Y value. The scroller will not scroll past this point.
|
| `maxY` | `int`: Maximum Y value. The scroller will not scroll past this point.
|
### forceFinished
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public final void forceFinished (boolean finished)
```
Force the finished field to a particular value.
| Parameters ||
|------------|-------------------------------------------|
| `finished` | `boolean`: The new finished value.
|
### getCurrVelocity
Added in[API level 14](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public float getCurrVelocity ()
```
Returns the current velocity.
| Returns ||
|---------|-----------------------------------------------------------------------------|
| `float` | The original velocity less the deceleration. Result may be negative.
|
### getCurrX
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public final int getCurrX ()
```
Returns the current X offset in the scroll.
| Returns ||
|-------|------------------------------------------------------------------|
| `int` | The new X offset as an absolute distance from the origin.
|
### getCurrY
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public final int getCurrY ()
```
Returns the current Y offset in the scroll.
| Returns ||
|-------|------------------------------------------------------------------|
| `int` | The new Y offset as an absolute distance from the origin.
|
### getDuration
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public final int getDuration ()
```
Returns how long the scroll event will take, in milliseconds.
| Returns ||
|-------|----------------------------------------------------|
| `int` | The duration of the scroll in milliseconds.
|
### getFinalX
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public final int getFinalX ()
```
Returns where the scroll will end. Valid only for "fling" scrolls.
| Returns ||
|-------|--------------------------------------------------------------------|
| `int` | The final X offset as an absolute distance from the origin.
|
### getFinalY
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public final int getFinalY ()
```
Returns where the scroll will end. Valid only for "fling" scrolls.
| Returns ||
|-------|--------------------------------------------------------------------|
| `int` | The final Y offset as an absolute distance from the origin.
|
### getStartX
Added in[API level 3](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public final int getStartX ()
```
Returns the start X offset in the scroll.
| Returns ||
|-------|--------------------------------------------------------------------|
| `int` | The start X offset as an absolute distance from the origin.
|
### getStartY
Added in[API level 3](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public final int getStartY ()
```
Returns the start Y offset in the scroll.
| Returns ||
|-------|--------------------------------------------------------------------|
| `int` | The start Y offset as an absolute distance from the origin.
|
### isFinished
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public final boolean isFinished ()
```
Returns whether the scroller has finished scrolling.
| Returns ||
|-----------|----------------------------------------------------------------------|
| `boolean` | True if the scroller has finished scrolling, false otherwise.
|
### setFinalX
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void setFinalX (int newX)
```
Sets the final position (X) for this scroller.
| Parameters ||
|--------|-------------------------------------------------------------------------|
| `newX` | `int`: The new X offset as an absolute distance from the origin.
|
**See also:**
- [extendDuration(int)](https://developer.android.com/reference/android/widget/Scroller#extendDuration(int))
- [setFinalY(int)](https://developer.android.com/reference/android/widget/Scroller#setFinalY(int))
### setFinalY
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void setFinalY (int newY)
```
Sets the final position (Y) for this scroller.
| Parameters ||
|--------|-------------------------------------------------------------------------|
| `newY` | `int`: The new Y offset as an absolute distance from the origin.
|
**See also:**
- [extendDuration(int)](https://developer.android.com/reference/android/widget/Scroller#extendDuration(int))
- [setFinalX(int)](https://developer.android.com/reference/android/widget/Scroller#setFinalX(int))
### setFriction
Added in[API level 11](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public final void setFriction (float friction)
```
The amount of friction applied to flings. The default value is[ViewConfiguration.getScrollFriction](https://developer.android.com/reference/android/view/ViewConfiguration#getScrollFriction()).
| Parameters ||
|------------|-----------------------------------------------------------------------------------------|
| `friction` | `float`: A scalar dimension-less value representing the coefficient of friction.
|
### startScroll
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void startScroll (int startX,
int startY,
int dx,
int dy,
int duration)
```
Start scrolling by providing a starting point, the distance to travel, and the duration of the scroll.
| Parameters ||
|------------|------------------------------------------------------------------------------------------------------------------|
| `startX` | `int`: Starting horizontal scroll offset in pixels. Positive numbers will scroll the content to the left.
|
| `startY` | `int`: Starting vertical scroll offset in pixels. Positive numbers will scroll the content up.
|
| `dx` | `int`: Horizontal distance to travel. Positive numbers will scroll the content to the left.
|
| `dy` | `int`: Vertical distance to travel. Positive numbers will scroll the content up.
|
| `duration` | `int`: Duration of the scroll in milliseconds.
|
### startScroll
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void startScroll (int startX,
int startY,
int dx,
int dy)
```
Start scrolling by providing a starting point and the distance to travel. The scroll will use the default value of 250 milliseconds for the duration.
| Parameters ||
|----------|------------------------------------------------------------------------------------------------------------------|
| `startX` | `int`: Starting horizontal scroll offset in pixels. Positive numbers will scroll the content to the left.
|
| `startY` | `int`: Starting vertical scroll offset in pixels. Positive numbers will scroll the content up.
|
| `dx` | `int`: Horizontal distance to travel. Positive numbers will scroll the content to the left.
|
| `dy` | `int`: Vertical distance to travel. Positive numbers will scroll the content up.
|
### timePassed
Added in[API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public int timePassed ()
```
Returns the time elapsed since the beginning of the scrolling.
| Returns ||
|-------|------------------------------------------|
| `int` | The elapsed time in milliseconds.
|