Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels) Summary: [Constants](https://developer.android.com/reference/android/nfc/tech/MifareClassic#constants) \| [Fields](https://developer.android.com/reference/android/nfc/tech/MifareClassic#lfields) \| [Methods](https://developer.android.com/reference/android/nfc/tech/MifareClassic#pubmethods) \| [Inherited Methods](https://developer.android.com/reference/android/nfc/tech/MifareClassic#inhmethods)
# MifareClassic
*** ** * ** ***
` public final class MifareClassic `
` extends https://developer.android.com/reference/java/lang/Object ` ` implements https://developer.android.com/reference/android/nfc/tech/TagTechnology `
|---|---|
| [java.lang.Object](https://developer.android.com/reference/java/lang/Object) ||
| ↳ | android.nfc.tech.MifareClassic |
*** ** * ** ***
Provides access to MIFARE Classic properties and I/O operations on a `https://developer.android.com/reference/android/nfc/Tag`.
Acquire a `https://developer.android.com/reference/android/nfc/tech/MifareClassic` object using `https://developer.android.com/reference/android/nfc/tech/MifareClassic#get(android.nfc.Tag)`.
MIFARE Classic is also known as MIFARE Standard.
MIFARE Classic tags are divided into sectors, and each sector is sub-divided into blocks. Block size is always 16 bytes (`https://developer.android.com/reference/android/nfc/tech/MifareClassic#BLOCK_SIZE`. Sector size varies.
- MIFARE Classic Mini are 320 bytes (`https://developer.android.com/reference/android/nfc/tech/MifareClassic#SIZE_MINI`), with 5 sectors each of 4 blocks.
- MIFARE Classic 1k are 1024 bytes (`https://developer.android.com/reference/android/nfc/tech/MifareClassic#SIZE_1K`), with 16 sectors each of 4 blocks.
- MIFARE Classic 2k are 2048 bytes (`https://developer.android.com/reference/android/nfc/tech/MifareClassic#SIZE_2K`), with 32 sectors each of 4 blocks.
- MIFARE Classic 4k are 4096 bytes (`https://developer.android.com/reference/android/nfc/tech/MifareClassic#SIZE_4K`). The first 32 sectors contain 4 blocks and the last 8 sectors contain 16 blocks.
MIFARE Classic tags require authentication on a per-sector basis before any other I/O operations on that sector can be performed. There are two keys per sector, and ACL bits determine what I/O operations are allowed on that sector after authenticating with a key. See `https://developer.android.com/reference/android/nfc/tech/MifareClassic#authenticateSectorWithKeyA(int,%20byte[])` and `https://developer.android.com/reference/android/nfc/tech/MifareClassic#authenticateSectorWithKeyB(int,%20byte[])`.
Three well-known authentication keys are defined in this class: `https://developer.android.com/reference/android/nfc/tech/MifareClassic#KEY_DEFAULT`, `https://developer.android.com/reference/android/nfc/tech/MifareClassic#KEY_MIFARE_APPLICATION_DIRECTORY`, `https://developer.android.com/reference/android/nfc/tech/MifareClassic#KEY_NFC_FORUM`.
- `https://developer.android.com/reference/android/nfc/tech/MifareClassic#KEY_DEFAULT` is the default factory key for MIFARE Classic.
- `https://developer.android.com/reference/android/nfc/tech/MifareClassic#KEY_MIFARE_APPLICATION_DIRECTORY` is the well-known key for MIFARE Classic cards that have been formatted according to the MIFARE Application Directory (MAD) specification.
- `https://developer.android.com/reference/android/nfc/tech/MifareClassic#KEY_NFC_FORUM` is the well-known key for MIFARE Classic cards that have been formatted according to the NXP specification for NDEF on MIFARE Classic.
Implementation of this class on a Android NFC device is optional. If it is not implemented, then `https://developer.android.com/reference/android/nfc/tech/MifareClassic` will never be enumerated in `https://developer.android.com/reference/android/nfc/Tag#getTechList()`. If it is enumerated, then all `https://developer.android.com/reference/android/nfc/tech/MifareClassic` I/O operations will be supported, and `https://developer.android.com/reference/android/nfc/tech/Ndef#MIFARE_CLASSIC` NDEF tags will also be supported. In either case, `https://developer.android.com/reference/android/nfc/tech/NfcA` will also be enumerated on the tag, because all MIFARE Classic tags are also `https://developer.android.com/reference/android/nfc/tech/NfcA`.
**Note:** Methods that perform I/O operations require the `https://developer.android.com/reference/android/Manifest.permission#NFC` permission.
## Summary
| ### Constants ||
|---|---|
| `int` | `https://developer.android.com/reference/android/nfc/tech/MifareClassic#BLOCK_SIZE` Size of a MIFARE Classic block (in bytes) |
| `int` | `https://developer.android.com/reference/android/nfc/tech/MifareClassic#SIZE_1K` Tag contains 16 sectors, each with 4 blocks. |
| `int` | `https://developer.android.com/reference/android/nfc/tech/MifareClassic#SIZE_2K` Tag contains 32 sectors, each with 4 blocks. |
| `int` | `https://developer.android.com/reference/android/nfc/tech/MifareClassic#SIZE_4K` Tag contains 40 sectors. |
| `int` | `https://developer.android.com/reference/android/nfc/tech/MifareClassic#SIZE_MINI` Tag contains 5 sectors, each with 4 blocks. |
| `int` | `https://developer.android.com/reference/android/nfc/tech/MifareClassic#TYPE_CLASSIC` A MIFARE Classic tag |
| `int` | `https://developer.android.com/reference/android/nfc/tech/MifareClassic#TYPE_PLUS` A MIFARE Plus tag |
| `int` | `https://developer.android.com/reference/android/nfc/tech/MifareClassic#TYPE_PRO` A MIFARE Pro tag |
| `int` | `https://developer.android.com/reference/android/nfc/tech/MifareClassic#TYPE_UNKNOWN` A MIFARE Classic compatible card of unknown type |
| ### Fields ||
|---|---|
| ` public static final byte[]` | `https://developer.android.com/reference/android/nfc/tech/MifareClassic#KEY_DEFAULT` The default factory key. |
| ` public static final byte[]` | `https://developer.android.com/reference/android/nfc/tech/MifareClassic#KEY_MIFARE_APPLICATION_DIRECTORY` The well-known key for tags formatted according to the MIFARE Application Directory (MAD) specification. |
| ` public static final byte[]` | `https://developer.android.com/reference/android/nfc/tech/MifareClassic#KEY_NFC_FORUM` The well-known key for tags formatted according to the NDEF on MIFARE Classic specification. |
| ### Public methods ||
|---|---|
| ` boolean` | ` https://developer.android.com/reference/android/nfc/tech/MifareClassic#authenticateSectorWithKeyA(int,%20byte[])(int sectorIndex, byte[] key) ` Authenticate a sector with key A. |
| ` boolean` | ` https://developer.android.com/reference/android/nfc/tech/MifareClassic#authenticateSectorWithKeyB(int,%20byte[])(int sectorIndex, byte[] key) ` Authenticate a sector with key B. |
| ` int` | ` https://developer.android.com/reference/android/nfc/tech/MifareClassic#blockToSector(int)(int blockIndex) ` Return the sector that contains a given block. |
| ` void` | ` https://developer.android.com/reference/android/nfc/tech/MifareClassic#close()() ` Disable I/O operations to the tag from this `https://developer.android.com/reference/android/nfc/tech/TagTechnology` object, and release resources. |
| ` void` | ` https://developer.android.com/reference/android/nfc/tech/MifareClassic#connect()() ` Enable I/O operations to the tag from this `https://developer.android.com/reference/android/nfc/tech/TagTechnology` object. |
| ` void` | ` https://developer.android.com/reference/android/nfc/tech/MifareClassic#decrement(int,%20int)(int blockIndex, int value) ` Decrement a value block, storing the result in the temporary block on the tag. |
| ` static https://developer.android.com/reference/android/nfc/tech/MifareClassic` | ` https://developer.android.com/reference/android/nfc/tech/MifareClassic#get(android.nfc.Tag)(https://developer.android.com/reference/android/nfc/Tag tag) ` Get an instance of `https://developer.android.com/reference/android/nfc/tech/MifareClassic` for the given tag. |
| ` int` | ` https://developer.android.com/reference/android/nfc/tech/MifareClassic#getBlockCount()() ` Return the total number of MIFARE Classic blocks. |
| ` int` | ` https://developer.android.com/reference/android/nfc/tech/MifareClassic#getBlockCountInSector(int)(int sectorIndex) ` Return the number of blocks in the given sector. |
| ` int` | ` https://developer.android.com/reference/android/nfc/tech/MifareClassic#getMaxTransceiveLength()() ` Return the maximum number of bytes that can be sent with `https://developer.android.com/reference/android/nfc/tech/MifareClassic#transceive(byte[])`. |
| ` int` | ` https://developer.android.com/reference/android/nfc/tech/MifareClassic#getSectorCount()() ` Return the number of MIFARE Classic sectors. |
| ` int` | ` https://developer.android.com/reference/android/nfc/tech/MifareClassic#getSize()() ` Return the size of the tag in bytes One of `https://developer.android.com/reference/android/nfc/tech/MifareClassic#SIZE_MINI`, `https://developer.android.com/reference/android/nfc/tech/MifareClassic#SIZE_1K`, `https://developer.android.com/reference/android/nfc/tech/MifareClassic#SIZE_2K`, `https://developer.android.com/reference/android/nfc/tech/MifareClassic#SIZE_4K`. |
| ` https://developer.android.com/reference/android/nfc/Tag` | ` https://developer.android.com/reference/android/nfc/tech/MifareClassic#getTag()() ` Get the `https://developer.android.com/reference/android/nfc/Tag` object backing this `https://developer.android.com/reference/android/nfc/tech/TagTechnology` object. |
| ` int` | ` https://developer.android.com/reference/android/nfc/tech/MifareClassic#getTimeout()() ` Get the current `https://developer.android.com/reference/android/nfc/tech/MifareClassic#transceive(byte[])` timeout in milliseconds. |
| ` int` | ` https://developer.android.com/reference/android/nfc/tech/MifareClassic#getType()() ` Return the type of this MIFARE Classic compatible tag. |
| ` void` | ` https://developer.android.com/reference/android/nfc/tech/MifareClassic#increment(int,%20int)(int blockIndex, int value) ` Increment a value block, storing the result in the temporary block on the tag. |
| ` boolean` | ` https://developer.android.com/reference/android/nfc/tech/MifareClassic#isConnected()() ` Helper to indicate if I/O operations should be possible. |
| ` byte[]` | ` https://developer.android.com/reference/android/nfc/tech/MifareClassic#readBlock(int)(int blockIndex) ` Read 16-byte block. |
| ` void` | ` https://developer.android.com/reference/android/nfc/tech/MifareClassic#restore(int)(int blockIndex) ` Copy from a value block to the temporary block. |
| ` int` | ` https://developer.android.com/reference/android/nfc/tech/MifareClassic#sectorToBlock(int)(int sectorIndex) ` Return the first block of a given sector. |
| ` void` | ` https://developer.android.com/reference/android/nfc/tech/MifareClassic#setTimeout(int)(int timeout) ` Set the `https://developer.android.com/reference/android/nfc/tech/MifareClassic#transceive(byte[])` timeout in milliseconds. |
| ` byte[]` | ` https://developer.android.com/reference/android/nfc/tech/MifareClassic#transceive(byte[])(byte[] data) ` Send raw NfcA data to a tag and receive the response. |
| ` void` | ` https://developer.android.com/reference/android/nfc/tech/MifareClassic#transfer(int)(int blockIndex) ` Copy from the temporary block to a value block. |
| ` void` | ` https://developer.android.com/reference/android/nfc/tech/MifareClassic#writeBlock(int,%20byte[])(int blockIndex, byte[] data) ` Write 16-byte block. |
### Inherited methods
From class ` https://developer.android.com/reference/java/lang/Object ` ` https://developer.android.com/reference/java/lang/Object` ` https://developer.android.com/reference/java/lang/Object#clone()() `
Creates and returns a copy of this object.
` boolean` ` https://developer.android.com/reference/java/lang/Object#equals(java.lang.Object)(https://developer.android.com/reference/java/lang/Object obj) `
Indicates whether some other object is "equal to" this one.
` void` ` 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 https://developer.android.com/reference/java/lang/Class` ` https://developer.android.com/reference/java/lang/Object#getClass()() `
Returns the runtime class of this `Object`.
` int` ` https://developer.android.com/reference/java/lang/Object#hashCode()() `
Returns a hash code value for the object.
` final void` ` https://developer.android.com/reference/java/lang/Object#notify()() `
Wakes up a single thread that is waiting on this object's monitor.
` final void` ` https://developer.android.com/reference/java/lang/Object#notifyAll()() `
Wakes up all threads that are waiting on this object's monitor.
` https://developer.android.com/reference/java/lang/String` ` https://developer.android.com/reference/java/lang/Object#toString()() `
Returns a string representation of the object.
` final void` ` 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` ` 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` ` 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*.
From interface ` https://developer.android.com/reference/android/nfc/tech/TagTechnology ` ` abstract void` ` https://developer.android.com/reference/android/nfc/tech/TagTechnology#close()() `
Disable I/O operations to the tag from this `https://developer.android.com/reference/android/nfc/tech/TagTechnology` object, and release resources.
` abstract void` ` https://developer.android.com/reference/android/nfc/tech/TagTechnology#connect()() `
Enable I/O operations to the tag from this `https://developer.android.com/reference/android/nfc/tech/TagTechnology` object.
` abstract https://developer.android.com/reference/android/nfc/Tag` ` https://developer.android.com/reference/android/nfc/tech/TagTechnology#getTag()() `
Get the `https://developer.android.com/reference/android/nfc/Tag` object backing this `https://developer.android.com/reference/android/nfc/tech/TagTechnology` object.
` abstract boolean` ` https://developer.android.com/reference/android/nfc/tech/TagTechnology#isConnected()() `
Helper to indicate if I/O operations should be possible.
From interface ` https://developer.android.com/reference/java/io/Closeable ` ` abstract void` ` https://developer.android.com/reference/java/io/Closeable#close()() `
Closes this stream and releases any system resources associated with it.
From interface ` https://developer.android.com/reference/java/lang/AutoCloseable ` ` abstract void` ` https://developer.android.com/reference/java/lang/AutoCloseable#close()() `
Closes this resource, relinquishing any underlying resources.
## Constants
### BLOCK_SIZE
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public static final int BLOCK_SIZE
```
Size of a MIFARE Classic block (in bytes)
Constant Value: 16 (0x00000010)
### SIZE_1K
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public static final int SIZE_1K
```
Tag contains 16 sectors, each with 4 blocks.
Constant Value: 1024 (0x00000400)
### SIZE_2K
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public static final int SIZE_2K
```
Tag contains 32 sectors, each with 4 blocks.
Constant Value: 2048 (0x00000800)
### SIZE_4K
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public static final int SIZE_4K
```
Tag contains 40 sectors. The first 32 sectors contain 4 blocks and the last 8 sectors contain 16 blocks.
Constant Value: 4096 (0x00001000)
### SIZE_MINI
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public static final int SIZE_MINI
```
Tag contains 5 sectors, each with 4 blocks.
Constant Value: 320 (0x00000140)
### TYPE_CLASSIC
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public static final int TYPE_CLASSIC
```
A MIFARE Classic tag
Constant Value: 0 (0x00000000)
### TYPE_PLUS
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public static final int TYPE_PLUS
```
A MIFARE Plus tag
Constant Value: 1 (0x00000001)
### TYPE_PRO
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public static final int TYPE_PRO
```
A MIFARE Pro tag
Constant Value: 2 (0x00000002)
### TYPE_UNKNOWN
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public static final int TYPE_UNKNOWN
```
A MIFARE Classic compatible card of unknown type
Constant Value: -1 (0xffffffff)
## Fields
### KEY_DEFAULT
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public static final byte[] KEY_DEFAULT
```
The default factory key.
### KEY_MIFARE_APPLICATION_DIRECTORY
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public static final byte[] KEY_MIFARE_APPLICATION_DIRECTORY
```
The well-known key for tags formatted according to the MIFARE Application Directory (MAD) specification.
### KEY_NFC_FORUM
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public static final byte[] KEY_NFC_FORUM
```
The well-known key for tags formatted according to the NDEF on MIFARE Classic specification.
## Public methods
### authenticateSectorWithKeyA
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public boolean authenticateSectorWithKeyA (int sectorIndex,
byte[] key)
```
Authenticate a sector with key A.
Successful authentication of a sector with key A enables other I/O operations on that sector. The set of operations granted by key A key depends on the ACL bits set in that sector. For more information see the MIFARE Classic specification on .
A failed authentication attempt causes an implicit reconnection to the tag, so authentication to other sectors will be lost.
This is an I/O operation and will block until complete. It must not be called from the main application thread. A blocked call will be canceled with `https://developer.android.com/reference/java/io/IOException` if `https://developer.android.com/reference/android/nfc/tech/MifareClassic#close()` is called from another thread.
Requires the `https://developer.android.com/reference/android/Manifest.permission#NFC` permission.
| Parameters ||
|---|---|
| `sectorIndex` | `int`: index of sector to authenticate, starting from 0
|
| `key` | `byte`: 6-byte authentication key
|
| Returns ||
|---|---|
| `boolean` | true on success, false on authentication failure
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/android/nfc/TagLostException` | if the tag leaves the field |
| `https://developer.android.com/reference/java/io/IOException` | if there is an I/O failure, or the operation is canceled |
### authenticateSectorWithKeyB
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public boolean authenticateSectorWithKeyB (int sectorIndex,
byte[] key)
```
Authenticate a sector with key B.
Successful authentication of a sector with key B enables other I/O operations on that sector. The set of operations granted by key B depends on the ACL bits set in that sector. For more information see the MIFARE Classic specification on .
A failed authentication attempt causes an implicit reconnection to the tag, so authentication to other sectors will be lost.
This is an I/O operation and will block until complete. It must not be called from the main application thread. A blocked call will be canceled with `https://developer.android.com/reference/java/io/IOException` if `https://developer.android.com/reference/android/nfc/tech/MifareClassic#close()` is called from another thread.
Requires the `https://developer.android.com/reference/android/Manifest.permission#NFC` permission.
| Parameters ||
|---|---|
| `sectorIndex` | `int`: index of sector to authenticate, starting from 0
|
| `key` | `byte`: 6-byte authentication key
|
| Returns ||
|---|---|
| `boolean` | true on success, false on authentication failure
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/android/nfc/TagLostException` | if the tag leaves the field |
| `https://developer.android.com/reference/java/io/IOException` | if there is an I/O failure, or the operation is canceled |
### blockToSector
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public int blockToSector (int blockIndex)
```
Return the sector that contains a given block.
Does not cause any RF activity and does not block.
| Parameters ||
|---|---|
| `blockIndex` | `int`: index of block to lookup, starting from 0
|
| Returns ||
|---|---|
| `int` | sector index that contains the block
|
### close
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void close ()
```
Disable I/O operations to the tag from this `https://developer.android.com/reference/android/nfc/tech/TagTechnology` object, and release resources.
Also causes all blocked I/O operations on other thread to be canceled and return with `https://developer.android.com/reference/java/io/IOException`.
Requires the `https://developer.android.com/reference/android/Manifest.permission#NFC` permission.
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/io/IOException` | |
### connect
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void connect ()
```
Enable I/O operations to the tag from this `https://developer.android.com/reference/android/nfc/tech/TagTechnology` object.
May cause RF activity and may block. Must not be called from the main application thread. A blocked call will be canceled with `https://developer.android.com/reference/java/io/IOException` by calling `https://developer.android.com/reference/android/nfc/tech/TagTechnology#close()` from another thread.
Only one `https://developer.android.com/reference/android/nfc/tech/TagTechnology` object can be connected to a `https://developer.android.com/reference/android/nfc/Tag` at a time.
Applications must call `https://developer.android.com/reference/android/nfc/tech/TagTechnology#close()` when I/O operations are complete.
Requires the `https://developer.android.com/reference/android/Manifest.permission#NFC` permission.
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/io/IOException` | |
### decrement
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void decrement (int blockIndex,
int value)
```
Decrement a value block, storing the result in the temporary block on the tag.
This is an I/O operation and will block until complete. It must not be called from the main application thread. A blocked call will be canceled with `https://developer.android.com/reference/java/io/IOException` if `https://developer.android.com/reference/android/nfc/tech/MifareClassic#close()` is called from another thread.
Requires the `https://developer.android.com/reference/android/Manifest.permission#NFC` permission.
| Parameters ||
|---|---|
| `blockIndex` | `int`: index of block to decrement, starting from 0
|
| `value` | `int`: non-negative to decrement by
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/android/nfc/TagLostException` | if the tag leaves the field |
| `https://developer.android.com/reference/java/io/IOException` | if there is an I/O failure, or the operation is canceled |
### get
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public static MifareClassic get (Tag tag)
```
Get an instance of `https://developer.android.com/reference/android/nfc/tech/MifareClassic` for the given tag.
Does not cause any RF activity and does not block.
Returns null if `https://developer.android.com/reference/android/nfc/tech/MifareClassic` was not enumerated in `https://developer.android.com/reference/android/nfc/Tag#getTechList()`. This indicates the tag is not MIFARE Classic compatible, or this Android device does not support MIFARE Classic.
| Parameters ||
|---|---|
| `tag` | `Tag`: an MIFARE Classic compatible tag
|
| Returns ||
|---|---|
| `https://developer.android.com/reference/android/nfc/tech/MifareClassic` | MIFARE Classic object
|
### getBlockCount
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public int getBlockCount ()
```
Return the total number of MIFARE Classic blocks.
Does not cause any RF activity and does not block.
| Returns ||
|---|---|
| `int` | total number of blocks
|
### getBlockCountInSector
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public int getBlockCountInSector (int sectorIndex)
```
Return the number of blocks in the given sector.
Does not cause any RF activity and does not block.
| Parameters ||
|---|---|
| `sectorIndex` | `int`: index of sector, starting from 0
|
| Returns ||
|---|---|
| `int` | number of blocks in the sector
|
### getMaxTransceiveLength
Added in [API level 14](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public int getMaxTransceiveLength ()
```
Return the maximum number of bytes that can be sent with `https://developer.android.com/reference/android/nfc/tech/MifareClassic#transceive(byte[])`.
| Returns ||
|---|---|
| `int` | the maximum number of bytes that can be sent with `https://developer.android.com/reference/android/nfc/tech/MifareClassic#transceive(byte[])`.
|
### getSectorCount
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public int getSectorCount ()
```
Return the number of MIFARE Classic sectors.
Does not cause any RF activity and does not block.
| Returns ||
|---|---|
| `int` | number of sectors
|
### getSize
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public int getSize ()
```
Return the size of the tag in bytes
One of `https://developer.android.com/reference/android/nfc/tech/MifareClassic#SIZE_MINI`, `https://developer.android.com/reference/android/nfc/tech/MifareClassic#SIZE_1K`, `https://developer.android.com/reference/android/nfc/tech/MifareClassic#SIZE_2K`, `https://developer.android.com/reference/android/nfc/tech/MifareClassic#SIZE_4K`. These constants are equal to their respective size in bytes.
Does not cause any RF activity and does not block.
| Returns ||
|---|---|
| `int` | size in bytes
|
### getTag
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public Tag getTag ()
```
Get the `https://developer.android.com/reference/android/nfc/Tag` object backing this `https://developer.android.com/reference/android/nfc/tech/TagTechnology` object.
| Returns ||
|---|---|
| `https://developer.android.com/reference/android/nfc/Tag` | the `https://developer.android.com/reference/android/nfc/Tag` backing this `https://developer.android.com/reference/android/nfc/tech/TagTechnology` object.
|
### getTimeout
Added in [API level 14](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public int getTimeout ()
```
Get the current `https://developer.android.com/reference/android/nfc/tech/MifareClassic#transceive(byte[])` timeout in milliseconds.
Requires the `https://developer.android.com/reference/android/Manifest.permission#NFC` permission.
| Returns ||
|---|---|
| `int` | timeout value in milliseconds
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/SecurityException` | if the tag object is reused after the tag has left the field |
### getType
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public int getType ()
```
Return the type of this MIFARE Classic compatible tag.
One of `https://developer.android.com/reference/android/nfc/tech/MifareClassic#TYPE_UNKNOWN`, `https://developer.android.com/reference/android/nfc/tech/MifareClassic#TYPE_CLASSIC`, `https://developer.android.com/reference/android/nfc/tech/MifareClassic#TYPE_PLUS` or `https://developer.android.com/reference/android/nfc/tech/MifareClassic#TYPE_PRO`.
Does not cause any RF activity and does not block.
| Returns ||
|---|---|
| `int` | type
|
### increment
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void increment (int blockIndex,
int value)
```
Increment a value block, storing the result in the temporary block on the tag.
This is an I/O operation and will block until complete. It must not be called from the main application thread. A blocked call will be canceled with `https://developer.android.com/reference/java/io/IOException` if `https://developer.android.com/reference/android/nfc/tech/MifareClassic#close()` is called from another thread.
Requires the `https://developer.android.com/reference/android/Manifest.permission#NFC` permission.
| Parameters ||
|---|---|
| `blockIndex` | `int`: index of block to increment, starting from 0
|
| `value` | `int`: non-negative to increment by
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/android/nfc/TagLostException` | if the tag leaves the field |
| `https://developer.android.com/reference/java/io/IOException` | if there is an I/O failure, or the operation is canceled |
### isConnected
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public boolean isConnected ()
```
Helper to indicate if I/O operations should be possible.
Returns true if `https://developer.android.com/reference/android/nfc/tech/TagTechnology#connect()` has completed, and `https://developer.android.com/reference/android/nfc/tech/TagTechnology#close()` has not been called, and the `https://developer.android.com/reference/android/nfc/Tag` is not known to be out of range.
Does not cause RF activity, and does not block.
| Returns ||
|---|---|
| `boolean` | true if I/O operations should be possible
|
### readBlock
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public byte[] readBlock (int blockIndex)
```
Read 16-byte block.
This is an I/O operation and will block until complete. It must not be called from the main application thread. A blocked call will be canceled with `https://developer.android.com/reference/java/io/IOException` if `https://developer.android.com/reference/android/nfc/tech/MifareClassic#close()` is called from another thread.
Requires the `https://developer.android.com/reference/android/Manifest.permission#NFC` permission.
| Parameters ||
|---|---|
| `blockIndex` | `int`: index of block to read, starting from 0
|
| Returns ||
|---|---|
| `byte[]` | 16 byte block
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/android/nfc/TagLostException` | if the tag leaves the field |
| `https://developer.android.com/reference/java/io/IOException` | if there is an I/O failure, or the operation is canceled |
### restore
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void restore (int blockIndex)
```
Copy from a value block to the temporary block.
This is an I/O operation and will block until complete. It must not be called from the main application thread. A blocked call will be canceled with `https://developer.android.com/reference/java/io/IOException` if `https://developer.android.com/reference/android/nfc/tech/MifareClassic#close()` is called from another thread.
Requires the `https://developer.android.com/reference/android/Manifest.permission#NFC` permission.
| Parameters ||
|---|---|
| `blockIndex` | `int`: index of block to copy from
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/android/nfc/TagLostException` | if the tag leaves the field |
| `https://developer.android.com/reference/java/io/IOException` | if there is an I/O failure, or the operation is canceled |
### sectorToBlock
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public int sectorToBlock (int sectorIndex)
```
Return the first block of a given sector.
Does not cause any RF activity and does not block.
| Parameters ||
|---|---|
| `sectorIndex` | `int`: index of sector to lookup, starting from 0
|
| Returns ||
|---|---|
| `int` | block index of first block in sector
|
### setTimeout
Added in [API level 14](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void setTimeout (int timeout)
```
Set the `https://developer.android.com/reference/android/nfc/tech/MifareClassic#transceive(byte[])` timeout in milliseconds.
The timeout only applies to `https://developer.android.com/reference/android/nfc/tech/MifareClassic#transceive(byte[])` on this object, and is reset to a default value when `https://developer.android.com/reference/android/nfc/tech/MifareClassic#close()` is called.
Setting a longer timeout may be useful when performing transactions that require a long processing time on the tag such as key generation.
Requires the `https://developer.android.com/reference/android/Manifest.permission#NFC` permission.
| Parameters ||
|---|---|
| `timeout` | `int`: timeout value in milliseconds
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/SecurityException` | if the tag object is reused after the tag has left the field |
### transceive
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public byte[] transceive (byte[] data)
```
Send raw NfcA data to a tag and receive the response.
This is equivalent to connecting to this tag via `https://developer.android.com/reference/android/nfc/tech/NfcA` and calling `https://developer.android.com/reference/android/nfc/tech/NfcA#transceive(byte[])`. Note that all MIFARE Classic tags are based on `https://developer.android.com/reference/android/nfc/tech/NfcA` technology.
Use `https://developer.android.com/reference/android/nfc/tech/MifareClassic#getMaxTransceiveLength()` to retrieve the maximum number of bytes that can be sent with `https://developer.android.com/reference/android/nfc/tech/MifareClassic#transceive(byte[])`.
This is an I/O operation and will block until complete. It must not be called from the main application thread. A blocked call will be canceled with `https://developer.android.com/reference/java/io/IOException` if `https://developer.android.com/reference/android/nfc/tech/MifareClassic#close()` is called from another thread.
Requires the `https://developer.android.com/reference/android/Manifest.permission#NFC` permission.
| Parameters ||
|---|---|
| `data` | `byte`
|
| Returns ||
|---|---|
| `byte[]` |
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/io/IOException` | |
**See also:**
- `https://developer.android.com/reference/android/nfc/tech/NfcA#transceive(byte[])`
### transfer
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void transfer (int blockIndex)
```
Copy from the temporary block to a value block.
This is an I/O operation and will block until complete. It must not be called from the main application thread. A blocked call will be canceled with `https://developer.android.com/reference/java/io/IOException` if `https://developer.android.com/reference/android/nfc/tech/MifareClassic#close()` is called from another thread.
Requires the `https://developer.android.com/reference/android/Manifest.permission#NFC` permission.
| Parameters ||
|---|---|
| `blockIndex` | `int`: index of block to copy to
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/android/nfc/TagLostException` | if the tag leaves the field |
| `https://developer.android.com/reference/java/io/IOException` | if there is an I/O failure, or the operation is canceled |
### writeBlock
Added in [API level 10](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void writeBlock (int blockIndex,
byte[] data)
```
Write 16-byte block.
This is an I/O operation and will block until complete. It must not be called from the main application thread. A blocked call will be canceled with `https://developer.android.com/reference/java/io/IOException` if `https://developer.android.com/reference/android/nfc/tech/MifareClassic#close()` is called from another thread.
Requires the `https://developer.android.com/reference/android/Manifest.permission#NFC` permission.
| Parameters ||
|---|---|
| `blockIndex` | `int`: index of block to write, starting from 0
|
| `data` | `byte`: 16 bytes of data to write
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/android/nfc/TagLostException` | if the tag leaves the field |
| `https://developer.android.com/reference/java/io/IOException` | if there is an I/O failure, or the operation is canceled |