Checking for existence of S3 bucket - Java AWS SDK 2

Question

Hi, what is the best way to check for the existence of an S3 bucket using the Java AWS SDK 2? I am not seeing relevant code examples for this. Thanks.

Accepted Answer

Hi,
To check for the existence of an S3 bucket using the Java AWS SDK 2, you can use the HeadBucketRequest class within the com.amazonaws.services.s3.AmazonS3 package. Here's an example:

```
AmazonS3 s3Client = AmazonS3Client.create();
HeadBucketRequest headBucketRequest = new HeadBucketRequest("your-bucket-name");
s3Client.headBucket(headBucketRequest);
```

If the bucket exists, this code will return a Bucket object. If not, it will throw a NoSuchBucketException. More information can be found in the official AWS SDK for Java 2 Developer Guide: https://docs.aws.amazon.com/sdk-for-java/v2/developer-guide/examples-s3-buckets.html

Answer

Depending on what you want to archive you can either use `headBucket` method of `S3Client` and check for `NoSuchBucketException` or if you just want to ensure it is created you may even try `createBucket` and catch exception:

* @throws BucketAlreadyExistsException
     *         The requested bucket name is not available. The bucket namespace is shared by all users of the system.
     *         Select a different name and try again.
     * @throws BucketAlreadyOwnedByYouException
     *         The bucket you tried to create already exists, and you own it. Amazon S3 returns this error in all AWS
     *         Regions except in the North Virginia Region. For legacy compatibility, if you re-create an existing
     *         bucket that you already own in the North Virginia Region, Amazon S3 returns 200 OK and resets the bucket
     *         access control lists (ACLs).

Answer

Hi,

For your need, check out: https://docs.aws.amazon.com/sdk-for-java/v1/developer-guide/examples-s3-buckets.html

They provide a code example:

```
import com.amazonaws.regions.Regions;
import com.amazonaws.services.s3.AmazonS3;
import com.amazonaws.services.s3.AmazonS3ClientBuilder;
import com.amazonaws.services.s3.model.AmazonS3Exception;
import com.amazonaws.services.s3.model.Bucket;

import java.util.List;

if (s3.doesBucketExistV2(bucket_name)) {
    System.out.format("Bucket %s already exists.
", bucket_name);
    b = getBucket(bucket_name);
} else {
    try {
        b = s3.createBucket(bucket_name);
    } catch (AmazonS3Exception e) {
        System.err.println(e.getErrorMessage());
    }
}
return b;
```

Best,

Didier

Checking for existence of S3 bucket - Java AWS SDK 2

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