要在Java中将HTML转换为PDF，可以使用iText库。以下是一个示例代码来执行此操作：

```java

import com.itextpdf.text.Document;

import com.itextpdf.text.html.simpleparser.HTMLWorker;

import com.itextpdf.text.pdf.PdfWriter;

import java.io.ByteArrayInputStream;

import java.io.ByteArrayOutputStream;

import java.io.FileOutputStream;

import java.io.InputStream;

import java.nio.charset.StandardCharsets;

public class HtmlToPdfConverter {

public static void main(String[] args) {

String htmlContent = "

Hello

world!

This is a sample HTML content.

String pdfFilePath = "output.pdf";

try {

InputStream inputStream = new ByteArrayInputStream(htmlContent.getBytes(StandardCharsets.UTF_8));

// Create output stream to write PDF file

FileOutputStream outputStream = new FileOutputStream(pdfFilePath);

// Create document

Document document = new Document();

PdfWriter writer = PdfWriter.getInstance(document

outputStream);

// Open document for writing

document.open();

// Parse HTML content and write it to the PDF document

HTMLWorker htmlWorker = new HTMLWorker(document);

htmlWorker.parse(inputStream);

// Close the document and output stream

document.close();

outputStream.close();

System.out.println("PDF file created successfully.");

} catch (Exception e) {

System.out.println("An error occurred: " + e);

}

}

}

```

请注意，此示例使用iText 5库，您需要将其添加到项目的依赖中。以下是一些常用的Maven依赖，可用于添加iText 5：

```xml

com.itextpdf

itextpdf

5.5.13

com.itextpdf.tool

xmlworker

5.5.13

```

希望这可以帮助您将HTML转换为PDF。