Java api : How to get already-created download link for a file?

Thanks for your answer. I'll post my fixed code for those who might have similar problem with mine.

	public String uploadFileAndGetLink(List<File> list, String dropboxPath) throws Exception {
		
		System.out.println();
		System.out.println("Getting download links...");
		StringBuilder sb = new StringBuilder("");
		
		for (File f : list) {
				
			String link;
			try {
				
				if(!isLinkExists(dropboxPath + f.getName())) {
					System.out.println("Uploading " + f.getName() + "...");
					uploadFile(f, dropboxPath);
					link = client.sharing().createSharedLinkWithSettings(dropboxPath + f.getName()).getUrl();
				} else {
					System.out.println(f.getName() + " is already uploaded, retrieving link...");
					link = client.sharing().listSharedLinksBuilder().withPath(dropboxPath + f.getName()).start().getLinks().get(0).getUrl();
				}
				
				sb.append(link.contains("dl=0") ? link.replace("dl=0", "dl=1") : (link.contains("?") ? link + "&dl=1" : link + "?dl=1"));
				sb.append(System.lineSeparator());
			
			} catch (Exception ex) {
				
				System.out.println();
				System.out.println("Failed to upload file \"" + f.getName() + "\": " + ex.getMessage());
				System.out.println("Try deleting uploaded files...");
				System.out.println();
				
				for (int i = 0; i < list.indexOf(f); i++) {
					
					deleteLink(dropboxPath + list.get(i).getName());

				}
				
				throw ex;
				
			}
		}
		
		System.out.println();
		return sb.toString();
	}
	
	private void uploadFile(File f, String path) throws Exception {

		FileInputStream in = new FileInputStream(f);

		UploadProgress prog = new UploadProgress(f);
		FileMetadata metadata = client.files().uploadBuilder(path + f.getName()).withMode(WriteMode.ADD)
				.withClientModified(new Date(f.lastModified())).uploadAndFinish(in, prog);
		System.out.println();
		System.out.println(f.getName() + "matadata : " + metadata.toStringMultiline());
		prog.done();

		in.close();

	}
	
	private boolean isLinkExists(String path) {
		
		boolean result = true;
		
        try {
            client.files().getMetadata(path);
        } catch (Exception e){
        	result = false;
        }

        return result;
		
	}
	
	private void deleteLink(String path) {
		
		try {
			
			if(isLinkExists(path)) client.files().deleteV2(path);
			
		} catch (Exception e) {
			System.out.println();
			System.out.println("Failed to delete uploaded file \"" + path + "\"");
			e.printStackTrace();
			System.out.println();
		}
		
	}