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# NameSpace Management
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NameSpace provides a facade for managing MMKV instances within custom root directories, enabling isolated storage environments for different application components or use cases.
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## Capabilities
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### NameSpace Creation
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Create and manage NameSpace instances with custom root directories.
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```java { .api }
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/**
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 * Create a NameSpace with custom root directory
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 * @param dir the customize root directory of a NameSpace
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 * @return a NameSpace with custom root dir
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 * @throws RuntimeException if there's an runtime error
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 */
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static NameSpace nameSpace(String dir);
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/**
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 * Get the default NameSpace identical with the original MMKV with the global root dir
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 * @throws RuntimeException if there's an runtime error
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 */
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static NameSpace defaultNameSpace();
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```
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**Usage Examples:**
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```java
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// Create custom NameSpace for user-specific data
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NameSpace userSpace = MMKV.nameSpace("/data/user_storage");
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String rootDir = userSpace.getRootDir();
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// Get default NameSpace
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NameSpace defaultNS = MMKV.defaultNameSpace();
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```
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### NameSpace Instance Management
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Create MMKV instances within the NameSpace's root directory.
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```java { .api }
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/**
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 * Create an MMKV instance with an unique ID (in single-process mode)
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 * @param mmapID The unique ID of the MMKV instance
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 * @throws RuntimeException if there's an runtime error
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 */
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MMKV mmkvWithID(String mmapID);
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/**
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 * Create an MMKV instance in single-process or multi-process mode
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 * @param mmapID The unique ID of the MMKV instance
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 * @param mode The process mode of the MMKV instance
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 * @throws RuntimeException if there's an runtime error
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 */
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MMKV mmkvWithID(String mmapID, int mode);
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/**
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 * Create an MMKV instance with expected capacity
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 * @param mmapID The unique ID of the MMKV instance
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 * @param mode The process mode of the MMKV instance
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 * @param expectedCapacity The file size you expected when opening or creating file
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 * @throws RuntimeException if there's an runtime error
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 */
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MMKV mmkvWithID(String mmapID, int mode, long expectedCapacity);
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/**
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 * Create an MMKV instance with encryption key
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 * @param mmapID The unique ID of the MMKV instance
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 * @param mode The process mode of the MMKV instance
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 * @param cryptKey The encryption key (no more than 16 bytes)
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 * @throws RuntimeException if there's an runtime error
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 */
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MMKV mmkvWithID(String mmapID, int mode, String cryptKey);
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/**
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 * Create an MMKV instance with all customize settings
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 * @param mmapID The unique ID of the MMKV instance
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 * @param mode The process mode of the MMKV instance
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 * @param cryptKey The encryption key (no more than 16 bytes)
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 * @param expectedCapacity The file size you expected when opening or creating file
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 * @throws RuntimeException if there's an runtime error
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 */
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MMKV mmkvWithID(String mmapID, int mode, String cryptKey, long expectedCapacity);
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```
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### NameSpace File Operations
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Manage MMKV storage files within the NameSpace.
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```java { .api }
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/**
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 * Check whether the MMKV file is valid or not
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 * Note: Don't use this to check the existence of the instance
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 * @param mmapID The unique ID of the MMKV instance
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 */
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boolean isFileValid(String mmapID);
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/**
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 * Remove the storage of the MMKV, including the data file & meta file (.crc)
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 * Note: the existing instance (if any) will be closed & destroyed
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 * @param mmapID The unique ID of the MMKV instance
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 */
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boolean removeStorage(String mmapID);
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/**
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 * Check existence of the MMKV file
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 * @param mmapID The unique ID of the MMKV instance
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 */
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boolean checkExist(String mmapID);
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```
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### NameSpace Backup and Restore
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Backup and restore operations within the NameSpace directory.
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```java { .api }
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/**
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 * Backup one MMKV instance to destination directory
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 * @param mmapID the MMKV ID to backup
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 * @param dstDir the backup destination directory
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 */
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boolean backupOneToDirectory(String mmapID, String dstDir);
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/**
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 * Restore one MMKV instance from source directory  
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 * @param mmapID the MMKV ID to restore
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 * @param srcDir the restore source directory
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 */
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boolean restoreOneMMKVFromDirectory(String mmapID, String srcDir);
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```
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## Types
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```java { .api }
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class NameSpace {
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    /**
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     * Get the root folder of this NameSpace
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     * @return The root folder path
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     */
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    String getRootDir();
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}
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```