get the Contents of a ZIP File in java

import java.util.*;
import java.util.zip.*;
import java.io.*;

public class ListZipFiles{
  public static void main(String[] args) throws IOException{
    ListZipFiles zf = new ListZipFiles();
  }

  public ListZipFiles() throws IOException{
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    System.out.print("Enter Zip file name: ");
    String filename = in.readLine();
//    File file = new File(filename);
    if(!filename.endsWith(".zip")){
      System.out.println("Invalid file name!");
      System.exit(0);
    }
    else if(!new File(filename).exists()){
      System.out.println("File not exist!");
      System.exit(0);
    }

    try{
      ZipFile zipFile = new ZipFile(filename);
      Enumeration em = zipFile.entries();
      for (Enumeration em1 = zipFile.entries(); em1.hasMoreElements();) {
        System.out.println(em1.nextElement());
      }
    }
    catch(ZipException ze){
      System.out.println(ze.getMessage());
      System.out.println("Zip file may be corrupted.");
      System.exit(0);
    }
  }
}