How to use .tbi for vcf file

[binfoUser]

I want to use indexed vcf files. For that I have a file .vcf and another file .tbi
I don't know how to use .tbi file. I'm using htsjdk library for Java but I don't know which methods to use.
For what I searched I have to use TabixIndexCreator and BlockCompressedInputStream to index and to read the file. Can someone give any ideas how to do that?

[binfoUser]

This is the code that I have so far:

VCFFileReader fileR= new VCFFileReader(f, fi, true);
VCFHeader fileHeader = fileR.getFileHeader();
VCFRecordCodec recCodec = new VCFRecordCodec(fileHeader);
        
TabixIndexCreator tic = new TabixIndexCreator(TabixFormat.VCF);
        
BlockCompressedInputStream inputStream = new BlockCompressedInputStream(new File("ex.vcf.gz")); 
long p = 0;
String rrline = inputStream.readLine();

CloseableIterator<VariantContext> vc = fileR.iterator();
    while(vc.hasNext()){
         VariantContext v = vc.next();
          tic.addFeature(v, p);
          p = inputStream.getFilePointer();
          rrline = inputStream.readLine();