How to delete all documents in mongodb collection in java

Using API >= 3.0:

MongoClient mongoClient = new MongoClient("127.0.0.1" , 27017);MongoDatabase db = mongoClient.getDatabase("maindb");db.getCollection("mainCollection").deleteMany(new Document());

To drop the collection (documents and indexes) you still can use:

db.getCollection("mainCollection").drop();

see https://docs.mongodb.org/getting-started/java/remove/#remove-all-documents

To remove all documents use the BasicDBObject or DBCursor as follows:

MongoClient client = new MongoClient("10.0.2.113" , 27017);MongoDatabase db = client.getDatabase("maindb");MongoCollection collection = db.getCollection("mainCollection")BasicDBObject document = new BasicDBObject();// Delete All documents from collection Using blank BasicDBObjectcollection.deleteMany(document);// Delete All documents from collection using DBCursorDBCursor cursor = collection.find();while (cursor.hasNext()) {    collection.remove(cursor.next());}

If you want to remove all documents in collection then used below code :

 db.getCollection("mainCollection").remove(new BasicDBObject());

Or If you want to drop whole collection then used this :

db.getCollection("mainCollection").drop();