import java. io. BufferedReader ;
import java. io. File ;
import java. io. FileReader ;
import java. io. IOException ;
import java. util. HashSet ;
import java. util. Set ;
public class FolderFileNames {
public static void main ( String [ ] args) {
String folderPath = "homework" ;
Set < String > setHomeWork = new HashSet < > ( ) ;
File folder = new File ( folderPath) ;
if ( folder. exists ( ) && folder. isDirectory ( ) ) {
String [ ] fileNames = folder. list ( ) ;
for ( String fileName : fileNames) {
System . out. println ( fileName) ;
setHomeWork. add ( fileName. split ( "\\." ) [ 0 ] ) ;
}
} else {
System . out. println ( "文件夹不存在或不是一个文件夹。" ) ;
}
Set < String > allStuNames = new HashSet < > ( ) ;
try {
FileReader fileReader = new FileReader ( "file.txt" ) ;
BufferedReader bufferedReader = new BufferedReader ( fileReader) ;
String line;
while ( ( line = bufferedReader. readLine ( ) ) != null ) {
System . out. println ( line) ;
allStuNames. add ( line) ;
}
bufferedReader. close ( ) ;
} catch ( IOException e) {
e. printStackTrace ( ) ;
}
allStuNames. removeAll ( setHomeWork) ;
System . out. println ( allStuNames) ;
}
}