Disk LRU Cache

Disk LRU (least recently used) cache with persisted journal. This cache has specific capacity and location. Rarely requested files are evicted by actively used.

Lightweight and extremely easy to use.

Add dependency

Step 1. Add the JitPack repository to your build file

allprojects {
	repositories {
		...
		maven { url 'https://jitpack.io' }
	}
}

Step 2. Add the dependency

implementation 'com.github.solkin:disk-lru-cache:<version>'

Replace <version> with the latest version from the JitPack badge above.

Create DiskLruCache

long CACHE_SIZE = 500 * 1024; // Size in bytes
DiskLruCache cache = DiskLruCache.create(getCacheDir(), CACHE_SIZE);

Add file into cache

To manage some files by cache you just need to invoke put method like any Map.

Key - any string to request this file from cache.

File - file, that will be moved into cache.

String key = "some-key";
File file = File.createTempFile("random", ".dat");
cache.put(key, file);

Getting file from cache

To get file from cache, just invoke get method. Yes, also like any Map.

Key is the same you put this file into cache

This method will return File you put into cache or null, if file was evicted from cache.

String key = "some-key";
File file = cache.get(key);

Delete file from cache

To delete file from cache, just invoke delete method.

Key is the same you put this file into cache.

File will be deleted from cache and from journal.

Throws RecordNotFoundException if the key is not found in cache.

String key = "some-key";
try {
    cache.delete(key);
} catch (RecordNotFoundException e) {
    // Key not found in cache
}

Clear cache

Sometime you may need to clear whole cache and drop all stored files.

cache.clearCache();

List keys in cache

To get all keys, managed by cache, invoke keySet() method.

This will return Set<String>.

List all keys in cache may be useful to check all files, stored in cache.

Set<String> keys = cache.keySet();

Get cache status information

There are some useful cache status information, that you can request.

cache.getCacheSize(); // Cache size in bytes, that you set up on cache creation.
cache.getUsedSpace(); // Size of all files, stored in cache.
cache.getFreeSpace(); // Free size in cache.
cache.getJournalSize(); // Internal cache journal size in bytes.

Get records information

To get detailed information about cached records including LRU order, use getRecordsInfo().

This returns a list of RecordInfo objects sorted by last access time (most recently accessed first). Records at the end of the list will be evicted first when cache overflows.

List<RecordInfo> records = cache.getRecordsInfo();
for (RecordInfo info : records) {
    String key = info.getKey();           // Key used to store the file
    String fileName = info.getFileName(); // Actual file name in cache
    long size = info.getSize();           // File size in bytes
    long lastAccessed = info.getLastAccessed(); // Timestamp of last access
}

To get information about a specific record without updating its access time:

RecordInfo info = cache.getRecordInfo("some-key");
if (info != null) {
    // Record exists
}

Note: getRecordInfo() and getRecordsInfo() do not update the access time, so they can be used for monitoring without affecting LRU order.

Thread safety

DiskLruCache is thread-safe. All public methods are synchronized and can be safely called from multiple threads.

Limitations

• File size cannot exceed cache size. Attempting to put a larger file will throw IOException.
• Key cannot be null or empty. Invalid keys will throw IllegalArgumentException.

Requirements

• Min SDK: 16 (Android 4.1)
• Target SDK: 34

Custom FileManager and Logger

You can provide custom implementations of FileManager and Logger:

FileManager fileManager = new MyCustomFileManager();
Logger logger = new MyCustomLogger();
DiskLruCache cache = DiskLruCache.create(fileManager, logger, CACHE_SIZE);

License

MIT License

Copyright (c) 2022-2026 Igor Solkin

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.