public static void changeObjectStorageClass(

String projectId, String bucketName, String objectName) {

// The ID of your GCP project

// String projectId = "your-project-id";

// The ID of your GCS bucket

// String bucketName = "your-unique-bucket-name";

// The ID of your GCS object

// String objectName = "your-object-name";

Storage storage = StorageOptions.newBuilder().setProjectId(projectId).build().getService();

BlobId blobId = BlobId.of(bucketName, objectName);

Blob sourceBlob = storage.get(blobId);

if (sourceBlob == null) {

System.out.println("The object " + objectName + " wasn't found in " + bucketName);

return;

}

// See the StorageClass documentation for other valid storage classes:

// https://googleapis.dev/java/google-cloud-clients/latest/com/google/cloud/storage/StorageClass.html

StorageClass storageClass = StorageClass.COLDLINE;

// You can't change an object's storage class directly, the only way is to rewrite the object

// with the desired storage class

BlobInfo targetBlob = BlobInfo.newBuilder(blobId).setStorageClass(storageClass).build();

// Optional: set a generation-match precondition to avoid potential race

// conditions and data corruptions. The request to upload returns a 412 error if

// the object's generation number does not match your precondition.

Storage.BlobSourceOption precondition =

Storage.BlobSourceOption.generationMatch(sourceBlob.getGeneration());

Storage.CopyRequest request =

Storage.CopyRequest.newBuilder()

.setSource(blobId)

.setSourceOptions(precondition) // delete this line to run without preconditions

.setTarget(targetBlob)

.build();

Blob updatedBlob = storage.copy(request).getResult();

System.out.println(

"Object "

+ objectName

+ " in bucket "

+ bucketName

+ " had its storage class set to "

+ updatedBlob.getStorageClass().name());

}