我有一個服務DocumentServiceImpl。在這里面我想運行一個方法index()的class GlobalSearch背景。@Service@RequiredArgsConstructor public class DocumentServiceImpl implements DocumentService { ... any code@Transactional public void save(){...  Thread indexTread = new Thread(new GlobalSearch(file, id), "GlobalSearch");  indexTread.start();.... }}方法index使用類GlobalSearch的從類ExtractTextFromFile方法。我使用構造函數和Lombok注釋@RequiredArgsConstructor注入類ExtractTextFromFile@Component@RequiredArgsConstructor public class GlobalSearch implements Runnable{ public final ExtractTextFromFile extractTextFromFile; (41 lines) public File file; public Long id; public GlobalSearch(File File, Long id){    this.file = file;    this.id = id;}public void index(File file, Long id) {    File textFile = extractTextFromFile.toText(file, id); ... code of this method}@Overridepublic void run() {    index(file, id);}...other methodspublic void search(){...}public String delete(){...}}..但IDE給出Variable 'extractTextFromFile' might not have been initialize了public final ExtractTextFromFile extractTextFromFile;如果我使用注入：@AutowiredExtractTextFromFile extractTextFromFile;然后給出錯誤：Exception in thread "GlobalSearch" java.lang.NullPointerExceptionat bps.module.zxc.component.GlobalSearch.index(GlobalSearch.java:41)at bps.module.zxc.component.GlobalSearch.run(GlobalSearch.java:136)at java.lang.Thread.run(Thread.java:748)此類ExtractTextFromFile：@Component@RequiredArgsConstructor public class ExtractTextFromFile { public File toText(File file, Long id) {  extractFromPfd();  extractFromWord(); }  extractFromPfd(){...};  extractFromWord(){...}; }