# PlaceholderDataSource

Artifact: [androidx.media3:media3-datasource](https://developer.android.com/jetpack/androidx/releases/media3) [View Source](https://cs.android.com/search?q=file:androidx/media3/datasource/PlaceholderDataSource.java+class:androidx.media3.datasource.PlaceholderDataSource)

*** ** * ** ***

<br />

```
@UnstableApi
class PlaceholderDataSource : DataSource
```

<br />

*** ** * ** ***

A DataSource which provides no data. `https://developer.android.com/reference/kotlin/androidx/media3/datasource/PlaceholderDataSource#open(androidx.media3.datasource.DataSpec)` throws `https://developer.android.com/reference/java/io/IOException.html`.

## Summary

| ### Constants |
|---|---|
| `const https://developer.android.com/reference/kotlin/androidx/media3/datasource/DataSource.Factory!` | `https://developer.android.com/reference/kotlin/androidx/media3/datasource/PlaceholderDataSource#FACTORY()` A factory that produces `https://developer.android.com/reference/kotlin/androidx/media3/datasource/PlaceholderDataSource`. |
| `const https://developer.android.com/reference/kotlin/androidx/media3/datasource/PlaceholderDataSource!` | `https://developer.android.com/reference/kotlin/androidx/media3/datasource/PlaceholderDataSource#INSTANCE()` |

| ### Public functions |
|---|---|
| `https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html` | `https://developer.android.com/reference/kotlin/androidx/media3/datasource/PlaceholderDataSource#addTransferListener(androidx.media3.datasource.TransferListener)(transferListener: https://developer.android.com/reference/kotlin/androidx/media3/datasource/TransferListener!)` Adds a `https://developer.android.com/reference/kotlin/androidx/media3/datasource/TransferListener` to listen to data transfers. |
| `https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-unit/index.html` | `https://developer.android.com/reference/kotlin/androidx/media3/datasource/PlaceholderDataSource#close()()` Closes the source. |
| `https://developer.android.com/reference/android/net/Uri.html?` | `https://developer.android.com/reference/kotlin/androidx/media3/datasource/PlaceholderDataSource#getUri()()` When the source is open, returns the `https://developer.android.com/reference/android/net/Uri.html` from which data is being read. |
| `https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-long/index.html` | `https://developer.android.com/reference/kotlin/androidx/media3/datasource/PlaceholderDataSource#open(androidx.media3.datasource.DataSpec)(dataSpec: https://developer.android.com/reference/kotlin/androidx/media3/datasource/DataSpec!)` Opens the source to read the specified data. |
| `https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html` | `https://developer.android.com/reference/kotlin/androidx/media3/datasource/PlaceholderDataSource#read(byte[],int,int)(buffer: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-byte-array/index.html<https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-byte/index.html>!, offset: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html, length: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html)` Reads up to `length` bytes of data from the input. |

### Inherited functions

From [androidx.media3.datasource.DataSource](https://developer.android.com/reference/kotlin/androidx/media3/datasource/DataSource) `(https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/-mutable-map/index.html)https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/-map/index.html<https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-string/index.html!, (https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/-mutable-list/index.html)https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/-list/index.html<https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-string/index.html!>!>!` `@https://developer.android.com/reference/kotlin/androidx/media3/common/util/UnstableApi
https://developer.android.com/reference/kotlin/androidx/media3/datasource/DataSource#getResponseHeaders()()`

When the source is open, returns the response headers associated with the last `https://developer.android.com/reference/kotlin/androidx/media3/datasource/DataSource#open(androidx.media3.datasource.DataSpec)` call.

## Constants

### FACTORY

```
const val FACTORY: DataSource.Factory!
```

A factory that produces `https://developer.android.com/reference/kotlin/androidx/media3/datasource/PlaceholderDataSource`.

### INSTANCE

```
const val INSTANCE: PlaceholderDataSource!
```

## Public functions

### addTransferListener

```
fun addTransferListener(transferListener: TransferListener!): Unit
```

Adds a `https://developer.android.com/reference/kotlin/androidx/media3/datasource/TransferListener` to listen to data transfers. This method is not thread-safe.

| Parameters |
|---|---|
| `transferListener: https://developer.android.com/reference/kotlin/androidx/media3/datasource/TransferListener!` | A `https://developer.android.com/reference/kotlin/androidx/media3/datasource/TransferListener`. |

### close

```
fun close(): Unit
```

Closes the source. This method must be called even if the corresponding call to `https://developer.android.com/reference/kotlin/androidx/media3/datasource/DataSource#open(androidx.media3.datasource.DataSpec)` threw an `https://developer.android.com/reference/java/io/IOException.html`.

| Throws |
|---|---|
| `https://developer.android.com/reference/java/io/IOException.html` | If an error occurs closing the source. |

### getUri

```
fun getUri(): Uri?
```

When the source is open, returns the `https://developer.android.com/reference/android/net/Uri.html` from which data is being read. The returned `https://developer.android.com/reference/android/net/Uri.html` will be identical to the one passed `https://developer.android.com/reference/kotlin/androidx/media3/datasource/DataSource#open(androidx.media3.datasource.DataSpec)` in the `https://developer.android.com/reference/kotlin/androidx/media3/datasource/DataSpec` unless redirection has occurred. If redirection has occurred, the `https://developer.android.com/reference/android/net/Uri.html` after redirection is returned.

| Returns |
|---|---|
| `https://developer.android.com/reference/android/net/Uri.html?` | The `https://developer.android.com/reference/android/net/Uri.html` from which data is being read, or null if the source is not open. |

### open

```
fun open(dataSpec: DataSpec!): Long
```

Opens the source to read the specified data. If an `https://developer.android.com/reference/java/io/IOException.html` is thrown, callers must still call `https://developer.android.com/reference/kotlin/androidx/media3/datasource/DataSource#close()` to ensure that any partial effects of the invocation are cleaned up.

The following edge case behaviors apply:

- If the `https://developer.android.com/reference/kotlin/androidx/media3/datasource/DataSpec#position()` is within the resource, but the `https://developer.android.com/reference/kotlin/androidx/media3/datasource/DataSpec#length()` extends beyond the end of the resource, then `https://developer.android.com/reference/kotlin/androidx/media3/datasource/DataSource#open(androidx.media3.datasource.DataSpec)` will succeed and data from the requested position to the end of the resource will be made available through `https://developer.android.com/reference/kotlin/androidx/media3/common/DataReader#read(byte[],int,int)`.
- If the `https://developer.android.com/reference/kotlin/androidx/media3/datasource/DataSpec#position()` is equal to the length of the resource, then `https://developer.android.com/reference/kotlin/androidx/media3/datasource/DataSource#open(androidx.media3.datasource.DataSpec)` will succeed, and `https://developer.android.com/reference/kotlin/androidx/media3/common/DataReader#read(byte[],int,int)` will immediately return `https://developer.android.com/reference/kotlin/androidx/media3/common/C#RESULT_END_OF_INPUT()`.
- If the `https://developer.android.com/reference/kotlin/androidx/media3/datasource/DataSpec#position()` is greater than the length of the resource, then `https://developer.android.com/reference/kotlin/androidx/media3/datasource/DataSource#open(androidx.media3.datasource.DataSpec)` will throw an `https://developer.android.com/reference/java/io/IOException.html` for which `https://developer.android.com/reference/kotlin/androidx/media3/datasource/DataSourceException#isCausedByPositionOutOfRange(java.io.IOException)` will be `true`.

| Parameters |
|---|---|
| `dataSpec: https://developer.android.com/reference/kotlin/androidx/media3/datasource/DataSpec!` | Defines the data to be read. |

| Returns |
|---|---|
| `https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-long/index.html` | The number of bytes that can be read from the opened source. For unbounded requests (i.e., requests where `https://developer.android.com/reference/kotlin/androidx/media3/datasource/DataSpec#length()` equals `https://developer.android.com/reference/kotlin/androidx/media3/common/C#LENGTH_UNSET()`) this value is the resolved length of the request, or `https://developer.android.com/reference/kotlin/androidx/media3/common/C#LENGTH_UNSET()` if the length is still unresolved. For all other requests, the value returned will be equal to the request's `https://developer.android.com/reference/kotlin/androidx/media3/datasource/DataSpec#length()`. |

| Throws |
|---|---|
| `https://developer.android.com/reference/java/io/IOException.html` | If an error occurs opening the source. `https://developer.android.com/reference/kotlin/androidx/media3/datasource/DataSourceException` can be thrown or used as a cause of the thrown exception to specify the reason of the error. |

### read

```
fun read(buffer: ByteArray<Byte>!, offset: Int, length: Int): Int
```

Reads up to `length` bytes of data from the input.

If `readLength` is zero then 0 is returned. Otherwise, if no data is available because the end of the opened range has been reached, then `https://developer.android.com/reference/kotlin/androidx/media3/common/C#RESULT_END_OF_INPUT()` is returned. Otherwise, the call will block until at least one byte of data has been read and the number of bytes read is returned.

| Parameters |
|---|---|
| `buffer: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-byte-array/index.html<https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-byte/index.html>!` | A target array into which data should be written. |
| `offset: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html` | The offset into the target array at which to write. |
| `length: https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html` | The maximum number of bytes to read from the input. |

| Returns |
|---|---|
| `https://kotlinlang.org/api/core/kotlin-stdlib/kotlin/-int/index.html` | The number of bytes read, or `https://developer.android.com/reference/kotlin/androidx/media3/common/C#RESULT_END_OF_INPUT()` if the input has ended. This may be less than `length` because the end of the input (or available data) was reached, the method was interrupted, or the operation was aborted early for another reason. |

| Throws |
|---|---|
| `https://developer.android.com/reference/java/io/IOException.html` | If an error occurs reading from the input. |