java - 长度无法解析或不是字段

Question

我是 Java 和 Android 的新手。

我的程序一直出现这个错误length cannot be resolved or is not a field 我只是不明白如何解决这个问题。这是代码

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;

import android.os.AsyncTask;
import android.os.Environment;

public class DownloadImages extends AsyncTask {


protected Object doInBackground(Object... params) {
    System.out.println("External Storage State = " + Environment.getExternalStorageState());
    File directory=new File(Environment.getExternalStorageDirectory(), "/Images");
    if (directory.exists()==false)
    {
        directory.mkdir();
    }
    for(int i = 0; i <URLS.length; i++) {
        try {
            File firstFile=new File(directory+"/" +i+ ".jpeg");
            if(firstFile.exists()==false)
            {
                HttpClient httpClient =new DefaultHttpClient();
                HttpGet httpGet =new HttpGet(URLS[i]);
                HttpResponse resp = httpClient.execute(httpGet);
                System.out.println("Status Code = " +resp.getStatusLine().getStatusCode());
                if(resp.getStatusLine().getStatusCode()==200)
                {
                    HttpEntity entity = resp.getEntity();
                    InputStream is = entity.getContent();
                    Boolean status = firstFile.createNewFile();

                    FileOutputStream foutS = new FileOutputStream(firstFile);
                    byte[] buffer = new byte[1024];
                    long total = 0;
                    int count;
                    while((count = is.read(buffer)) != -1){
                        total += count;
                        foutS.write(buffer, 0, count);
                    }
                    foutS.close();
                    is.close();
                    publishProgress(i);

                    }
                }

            }catch(MalformedURLException e){
                e.printStackTrace();
            }catch(ClientProtocolException e){
                e.printStackTrace();
            }catch(IOException e){
                e.printStackTrace();
            }
    }
    return null;
        }

@SuppressWarnings("unchecked")
protected void onProgressUpdate(Object... values){
    super.onProgressUpdate(values);

    }
}

在 For 语句行中获取错误

  for(int i = 0; i <URLS.length; i++) {

MainActivity.java

import android.os.Bundle;
 import android.app.Activity;
 import android.view.Menu;

 public class MainActivity extends Activity{

private static final String[] URLS = {
    "http://cdn.cs76.net/2011/spring/lectures/6/imgs/img_2851.jpg",
        "http://cdn.cs76.net/2011/spring/lectures/6/imgs/img_2944.jpg",
        "http://cdn.cs76.net/2011/spring/lectures/6/imgs/img_2989.jpg",
        "http://cdn.cs76.net/2011/spring/lectures/6/imgs/img_3005.jpg",
        "http://cdn.cs76.net/2011/spring/lectures/6/imgs/img_3012.jpg",
        "http://cdn.cs76.net/2011/spring/lectures/6/imgs/img_3034.jpg",
        "http://cdn.cs76.net/2011/spring/lectures/6/imgs/img_3047.jpg",
        "http://cdn.cs76.net/2011/spring/lectures/6/imgs/img_3092.jpg",
        "http://cdn.cs76.net/2011/spring/lectures/6/imgs/img_3110.jpg",
        "http://cdn.cs76.net/2011/spring/lectures/6/imgs/img_3113.jpg",
        "http://cdn.cs76.net/2011/spring/lectures/6/imgs/img_3128.jpg",
        "http://cdn.cs76.net/2011/spring/lectures/6/imgs/img_3160.jpg",
};
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    new DownloadImages().execute();
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.activity_main, menu);
    return true;
}
}

Answer 1

公开 URL

public static final String[] URLS = {

并将其用作

for(int i = 0; i <MainActivity.URLS.length; i++) {

试一试..