CreateFlag (Apache Hadoop Main 3.4.2 API)

java.lang.Object
- java.lang.Enum<CreateFlag>
- - org.apache.hadoop.fs.CreateFlag

All Implemented Interfaces:

Serializable, Comparable<CreateFlag>
```
@InterfaceAudience.Public
 @InterfaceStability.Evolving
public enum CreateFlag
extends Enum<CreateFlag>
```
CreateFlag specifies the file create semantic. Users can combine flags like:
EnumSet.of(CreateFlag.CREATE, CreateFlag.APPEND)
Use the CreateFlag as follows:
1. CREATE - to create a file if it does not exist, else throw FileAlreadyExists.
2. APPEND - to append to a file if it exists, else throw FileNotFoundException.
3. OVERWRITE - to truncate a file if it exists, else throw FileNotFoundException.
4. CREATE|APPEND - to create a file if it does not exist, else append to an existing file.
5. CREATE|OVERWRITE - to create a file if it does not exist, else overwrite an existing file.
6. SYNC_BLOCK - to force closed blocks to the disk device. In addition Syncable.hsync() should be called after each write, if true synchronous behavior is required.
7. LAZY_PERSIST - Create the block on transient storage (RAM) if available.
8. APPEND_NEWBLOCK - Append data to a new block instead of end of the last partial block.
Following combinations are not valid and will result in HadoopIllegalArgumentException:
1. APPEND|OVERWRITE
2. CREATE|APPEND|OVERWRITE

Enum Constant Summary

Enum Constants
Enum Constant and Description
`APPEND` Append to a file.
`CREATE` Create a file.
`IGNORE_CLIENT_LOCALITY` Advise that the first block replica NOT take into account DataNode locality.
`LAZY_PERSIST` Create the block on transient storage (RAM) if available.
`NEW_BLOCK` Append data to a new block instead of the end of the last partial block.
`NO_LOCAL_RACK` Advise that a block replica NOT be written to the local rack DataNode where 'local' means the same rack as the client is being run on.
`NO_LOCAL_WRITE` Advise that a block replica NOT be written to the local DataNode where 'local' means the same host as the client is being run on.
`OVERWRITE` Truncate/overwrite a file.
`SHOULD_REPLICATE` Enforce the file to be a replicated file, no matter what its parent directory's replication or erasure coding policy is.
`SYNC_BLOCK` Force closed blocks to disk.

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`static void`	`validate(EnumSet<CreateFlag> flag)` Validate the CreateFlag and throw exception if it is invalid
`static void`	`validate(Object path, boolean pathExists, EnumSet<CreateFlag> flag)` Validate the CreateFlag for create operation
`static void`	`validateForAppend(EnumSet<CreateFlag> flag)` Validate the CreateFlag for the append operation.
`static CreateFlag`	`valueOf(String name)` Returns the enum constant of this type with the specified name.
`static CreateFlag[]`	`values()` Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum
clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object
getClass, notify, notifyAll, wait, wait, wait

- Enum Constant Detail
  - CREATE
```
public static final CreateFlag CREATE
```
    Create a file. See javadoc for more description already exists
  - OVERWRITE
```
public static final CreateFlag OVERWRITE
```
    Truncate/overwrite a file. Same as POSIX O_TRUNC. See javadoc for description.
  - APPEND
```
public static final CreateFlag APPEND
```
    Append to a file. See javadoc for more description.
  - SYNC_BLOCK
```
public static final CreateFlag SYNC_BLOCK
```
    Force closed blocks to disk. Similar to POSIX O_SYNC. See javadoc for description.
  - LAZY_PERSIST
```
public static final CreateFlag LAZY_PERSIST
```
    Create the block on transient storage (RAM) if available. If transient storage is unavailable then the block will be created on disk. HDFS will make a best effort to lazily write these files to persistent storage, however file contents may be lost at any time due to process/ node restarts, hence there is no guarantee of data durability. This flag must only be used for intermediate data whose loss can be tolerated by the application.
  - NEW_BLOCK
```
public static final CreateFlag NEW_BLOCK
```
    Append data to a new block instead of the end of the last partial block. This is only useful for APPEND.
  - NO_LOCAL_WRITE
```
@InterfaceAudience.LimitedPrivate(value="HBase")
public static final CreateFlag NO_LOCAL_WRITE
```
    Advise that a block replica NOT be written to the local DataNode where 'local' means the same host as the client is being run on.
  - SHOULD_REPLICATE
```
public static final CreateFlag SHOULD_REPLICATE
```
    Enforce the file to be a replicated file, no matter what its parent directory's replication or erasure coding policy is.
  - IGNORE_CLIENT_LOCALITY
```
public static final CreateFlag IGNORE_CLIENT_LOCALITY
```
    Advise that the first block replica NOT take into account DataNode locality. The first block replica should be placed randomly within the cluster. Subsequent block replicas should follow DataNode locality rules.
  - NO_LOCAL_RACK
```
public static final CreateFlag NO_LOCAL_RACK
```
    Advise that a block replica NOT be written to the local rack DataNode where 'local' means the same rack as the client is being run on.
- Method Detail
  - values
```
public static CreateFlag[] values()
```
    Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:
```
for (CreateFlag c : CreateFlag.values())
    System.out.println(c);
```
    Returns:
    
    an array containing the constants of this enum type, in the order they are declared
  - valueOf
```
public static CreateFlag valueOf(String name)
```
    Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)
    
    Parameters:
    
    name - the name of the enum constant to be returned.
    
    Returns:
    
    the enum constant with the specified name
    
    Throws:
    
    IllegalArgumentException - if this enum type has no constant with the specified name
    
    NullPointerException - if the argument is null
  - validate
```
public static void validate(EnumSet<CreateFlag> flag)
```
    Validate the CreateFlag and throw exception if it is invalid
    
    Parameters:
    
    flag - set of CreateFlag
    
    Throws:
    
    HadoopIllegalArgumentException - if the CreateFlag is invalid
  - validate
```
public static void validate(Object path,
                            boolean pathExists,
                            EnumSet<CreateFlag> flag)
                     throws IOException
```
    Validate the CreateFlag for create operation
    
    Parameters:
    
    path - Object representing the path; usually String or Path
    
    pathExists - pass true if the path exists in the file system
    
    flag - set of CreateFlag
    
    Throws:
    
    IOException - on error
    
    HadoopIllegalArgumentException - if the CreateFlag is invalid
  - validateForAppend
```
public static void validateForAppend(EnumSet<CreateFlag> flag)
```
    Validate the CreateFlag for the append operation. The flag must contain APPEND, and cannot contain OVERWRITE.
    
    Parameters:
    
    flag - enum set flag.

Enum CreateFlag

Enum Constant Summary

Method Summary

Methods inherited from class java.lang.Enum

Methods inherited from class java.lang.Object

Enum Constant Detail

CREATE

OVERWRITE

APPEND

SYNC_BLOCK

LAZY_PERSIST

NEW_BLOCK

NO_LOCAL_WRITE

SHOULD_REPLICATE

IGNORE_CLIENT_LOCALITY

NO_LOCAL_RACK

Method Detail

values

valueOf

validate

validate

validateForAppend