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    Create a Cloud Storage reference on Android

    Your files are stored in a Cloud Storage bucket. The files in this bucket are presented in a hierarchical structure, just like the file system on your local hard disk, or the data in the Firebase Realtime Database . By creating a reference to a file, your app gains access to it. These references can then be used to upload or download data, get or update metadata or delete the file. A reference can either point to a specific file or to a higher level node in the hierarchy.

    If you've used the Firebase Realtime Database , these paths should seem very familiar to you. However, your file data is stored in Cloud Storage , notin the Realtime Database .

    Create a Reference

    Create a reference to upload, download, or delete a file, or to get or update its metadata. A reference can be thought of as a pointer to a file in the cloud. References are lightweight, so you can create as many as you need. They are also reusable for multiple operations.

    Create a reference using the FirebaseStorage singleton instance and calling its getReference() method.

    Kotlin 

     // Create a storage reference from our app 
 var 
  
 storageRef 
  
 = 
  
 storage 
 . 
 reference 
     StorageActivity 

     
     
 . 
 kt

    Java 

     // Create a storage reference from our app 
 StorageReference 
  
 storageRef 
  
 = 
  
 storage 
 . 
 getReference 
 (); 
 
      StorageActivity 
 . 
 java

    Next, you can create a reference to a location lower in the tree, say "images/space.jpg" by using the child() method on an existing reference.

    Kotlin 

     // Create a child reference 
 // imagesRef now points to "images" 
 var 
  
 imagesRef 
 : 
  
 StorageReference? 
 = 
  
 storageRef 
 . 
 child 
 ( 
 "images" 
 ) 
 // Child references can also take paths 
 // spaceRef now points to "images/space.jpg 
 // imagesRef still points to "images" 
 var 
  
 spaceRef 
  
 = 
  
 storageRef 
 . 
 child 
 ( 
 "images/space.jpg" 
 ) 
 
      StorageActivity 
 . 
 kt

    Java 

     // Create a child reference 
 // imagesRef now points to "images" 
 StorageReference 
  
 imagesRef 
  
 = 
  
 storageRef 
 . 
 child 
 ( 
 "images" 
 ); 
 // Child references can also take paths 
 // spaceRef now points to "images/space.jpg 
 // imagesRef still points to "images" 
 StorageReference 
  
 spaceRef 
  
 = 
  
 storageRef 
 . 
 child 
 ( 
 "images/space.jpg" 
 ); 
 
      StorageActivity 
 . 
 java

    You can also use the getParent() and getRoot() methods to navigate up in our file hierarchy. getParent() navigates up one level, while getRoot() navigates all the way to the top.

    Kotlin 

     // parent allows us to move our reference to a parent node 
 // imagesRef now points to 'images' 
 imagesRef 
  
 = 
  
 spaceRef 
 . 
 parent 
 // root allows us to move all the way back to the top of our bucket 
 // rootRef now points to the root 
 val 
  
 rootRef 
  
 = 
  
 spaceRef 
 . 
 root 
     StorageActivity 

     
     
 . 
 kt

    Java 

     // getParent allows us to move our reference to a parent node 
 // imagesRef now points to 'images' 
 imagesRef 
  
 = 
  
 spaceRef 
 . 
 getParent 
 (); 
 // getRoot allows us to move all the way back to the top of our bucket 
 // rootRef now points to the root 
 StorageReference 
  
 rootRef 
  
 = 
  
 spaceRef 
 . 
 getRoot 
 (); 
 
      StorageActivity 
 . 
 java

    child() , getParent() , and getRoot() can be chained together multiple times, as each returns a reference. But calling getRoot().getParent() returns null .

    Kotlin 

     // References can be chained together multiple times 
 // earthRef points to 'images/earth.jpg' 
 val 
  
 earthRef 
  
 = 
  
 spaceRef 
 . 
 parent 
 ?. 
 child 
 ( 
 "earth.jpg" 
 ) 
 // nullRef is null, since the parent of root is null 
 val 
  
 nullRef 
  
 = 
  
 spaceRef 
 . 
 root 
 . 
 parent 
     StorageActivity 

     
     
 . 
 kt

    Java 

     // References can be chained together multiple times 
 // earthRef points to 'images/earth.jpg' 
 StorageReference 
  
 earthRef 
  
 = 
  
 spaceRef 
 . 
 getParent 
 (). 
 child 
 ( 
 "earth.jpg" 
 ); 
 // nullRef is null, since the parent of root is null 
 StorageReference 
  
 nullRef 
  
 = 
  
 spaceRef 
 . 
 getRoot 
 (). 
 getParent 
 (); 
 
      StorageActivity 
 . 
 java

    Reference Properties

    You can inspect references to better understand the files they point to using the getPath() , getName() , and getBucket() methods. These methods get the file's full path, name and bucket.

    Kotlin 

     // Reference's path is: "images/space.jpg" 
 // This is analogous to a file path on disk 
 spaceRef 
 . 
 path 
 // Reference's name is the last segment of the full path: "space.jpg" 
 // This is analogous to the file name 
 spaceRef 
 . 
 name 
 // Reference's bucket is the name of the storage bucket that the files are stored in 
 spaceRef 
 . 
 bucket 
     StorageActivity 

     
     
 . 
 kt

    Java 

     // Reference's path is: "images/space.jpg" 
 // This is analogous to a file path on disk 
 spaceRef 
 . 
 getPath 
 (); 
 // Reference's name is the last segment of the full path: "space.jpg" 
 // This is analogous to the file name 
 spaceRef 
 . 
 getName 
 (); 
 // Reference's bucket is the name of the storage bucket that the files are stored in 
 spaceRef 
 . 
 getBucket 
 (); 
 
      StorageActivity 
 . 
 java

    Limitations on References

    Reference paths and names can contain any sequence of valid Unicode characters, but certain restrictions are imposed including:

    1. Total length of reference.fullPath must be between 1 and 1024 bytes when UTF-8 encoded.
    2. No Carriage Return or Line Feed characters.
    3. Avoid using # , [ , ] , * , or ? , as these do not work well with other tools such as the Firebase Realtime Database or gsutil .

    Full Example

    Kotlin 

     // Points to the root reference 
 storageRef 
  
 = 
  
 storage 
 . 
 reference 
 // Points to "images" 
 imagesRef 
  
 = 
  
 storageRef 
 . 
 child 
 ( 
 "images" 
 ) 
 // Points to "images/space.jpg" 
 // Note that you can use variables to create child values 
 val 
  
 fileName 
  
 = 
  
 "space.jpg" 
 spaceRef 
  
 = 
  
 imagesRef 
 . 
 child 
 ( 
 fileName 
 ) 
 // File path is "images/space.jpg" 
 val 
  
 path 
  
 = 
  
 spaceRef 
 . 
 path 
 // File name is "space.jpg" 
 val 
  
 name 
  
 = 
  
 spaceRef 
 . 
 name 
 // Points to "images" 
 imagesRef 
  
 = 
  
 spaceRef 
 . 
 parent 
     StorageActivity 

     
     
 . 
 kt

    Java 

     // Points to the root reference 
 storageRef 
  
 = 
  
 storage 
 . 
 getReference 
 (); 
 // Points to "images" 
 imagesRef 
  
 = 
  
 storageRef 
 . 
 child 
 ( 
 "images" 
 ); 
 // Points to "images/space.jpg" 
 // Note that you can use variables to create child values 
 String 
  
 fileName 
  
 = 
  
 "space.jpg" 
 ; 
 spaceRef 
  
 = 
  
 imagesRef 
 . 
 child 
 ( 
 fileName 
 ); 
 // File path is "images/space.jpg" 
 String 
  
 path 
  
 = 
  
 spaceRef 
 . 
 getPath 
 (); 
 // File name is "space.jpg" 
 String 
  
 name 
  
 = 
  
 spaceRef 
 . 
 getName 
 (); 
 // Points to "images" 
 imagesRef 
  
 = 
  
 spaceRef 
 . 
 getParent 
 (); 
 
      StorageActivity 
 . 
 java

    Next, let's learn how to upload files to Cloud Storage .

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