Exists API

It uses GetRequest just like the Get API. All of its optional arguments are supported. Since exists() only returns true or false, we recommend turning off fetching _source and any stored fields so the request is slightly lighter:

GetRequest getRequest = new GetRequest(
    "posts", 
    "doc",   
    "1");    
getRequest.fetchSourceContext(new FetchSourceContext(false)); 
getRequest.storedFields("_none_");                            

When executing a GetRequest in the following manner, the client waits for the boolean to be returned before continuing with code execution:

boolean exists = client.exists(getRequest, RequestOptions.DEFAULT);

Executing a GetRequest can also be done in an asynchronous fashion so that the client can return directly. Users need to specify how the response or potential failures will be handled by passing the request and a listener to the asynchronous exists method:

client.existsAsync(getRequest, RequestOptions.DEFAULT, listener); 

The asynchronous method does not block and returns immediately. Once it is completed the ActionListener is called back using the onResponse method if the execution successfully completed or using the onFailure method if it failed.

A typical listener for exists looks like:

ActionListener<Boolean> listener = new ActionListener<Boolean>() {
    @Override
    public void onResponse(Boolean exists) {
        
    }

    @Override
    public void onFailure(Exception e) {
        
    }
};