# ViewPager.SimpleOnPageChangeListener

Artifact: [androidx.viewpager:viewpager](https://developer.android.com/jetpack/androidx/releases/viewpager) [View Source](https://cs.android.com/search?q=file:androidx/viewpager/widget/ViewPager.java+class:androidx.viewpager.widget.ViewPager.SimpleOnPageChangeListener) Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/viewpager#1.1.0)

*** ** * ** ***


```
public class ViewPager.SimpleOnPageChangeListener implements ViewPager.OnPageChangeListener
```

<br />

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Simple implementation of the `https://developer.android.com/reference/androidx/viewpager/widget/ViewPager.OnPageChangeListener` interface with stub implementations of each method. Extend this if you do not intend to override every method of `https://developer.android.com/reference/androidx/viewpager/widget/ViewPager.OnPageChangeListener`.

## Summary

| ### Public constructors |
|---|
| `https://developer.android.com/reference/androidx/viewpager/widget/ViewPager.SimpleOnPageChangeListener#SimpleOnPageChangeListener()()` |

| ### Public methods |
|---|---|
| `void` | `https://developer.android.com/reference/androidx/viewpager/widget/ViewPager.SimpleOnPageChangeListener#onPageScrollStateChanged(int)(int state)` Called when the scroll state changes. |
| `void` | `https://developer.android.com/reference/androidx/viewpager/widget/ViewPager.SimpleOnPageChangeListener#onPageScrolled(int,float,int)( int position, float positionOffset, int positionOffsetPixels )` This method will be invoked when the current page is scrolled, either as part of a programmatically initiated smooth scroll or a user initiated touch scroll. |
| `void` | `https://developer.android.com/reference/androidx/viewpager/widget/ViewPager.SimpleOnPageChangeListener#onPageSelected(int)(int position)` This method will be invoked when a new page becomes selected. |

## Public constructors

### SimpleOnPageChangeListener

Added in 1.1.0

```
public SimpleOnPageChangeListener()
```

## Public methods

### onPageScrollStateChanged

Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/viewpager#1.1.0)

```
public void onPageScrollStateChanged(int state)
```

Called when the scroll state changes. Useful for discovering when the user begins dragging, when the pager is automatically settling to the current page, or when it is fully stopped/idle.

| Parameters |
|---|---|
| `int state` | The new scroll state. |

| See also |
|---|---|
| `https://developer.android.com/reference/androidx/viewpager/widget/ViewPager#SCROLL_STATE_IDLE()` |   |
| `https://developer.android.com/reference/androidx/viewpager/widget/ViewPager#SCROLL_STATE_DRAGGING()` |   |
| `https://developer.android.com/reference/androidx/viewpager/widget/ViewPager#SCROLL_STATE_SETTLING()` |   |

### onPageScrolled

Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/viewpager#1.1.0)

```
public void onPageScrolled(
    int position,
    float positionOffset,
    int positionOffsetPixels
)
```

This method will be invoked when the current page is scrolled, either as part of a programmatically initiated smooth scroll or a user initiated touch scroll.

| Parameters |
|---|---|
| `int position` | Position index of the first page currently being displayed. Page position+1 will be visible if positionOffset is nonzero. |
| `float positionOffset` | Value from \[0, 1) indicating the offset from the page at position. |
| `int positionOffsetPixels` | Value in pixels indicating the offset from position. |

### onPageSelected

Added in [1.1.0](https://developer.android.com/jetpack/androidx/releases/viewpager#1.1.0)

```
public void onPageSelected(int position)
```

This method will be invoked when a new page becomes selected. Animation is not necessarily complete.

| Parameters |
|---|---|
| `int position` | Position index of the new selected page. |