는 시도 캐치에서 문자열 값을 전달하는 데 도움이 필요

Question

내가 문자열 URL 텍스트 파일에서 모든 텍스트를 읽기 위해 노력하고 있지만 내가 이러한 오류 데 :

package com.example.imagedownloadsample; 

import java.io.BufferedReader; 
import java.io.File; 
import java.io.FileOutputStream; 
import java.io.IOException; 
import java.io.InputStreamReader; 
import java.net.MalformedURLException; 
import java.net.URL; 

import android.graphics.Bitmap; 
import android.graphics.Bitmap.CompressFormat; 
import android.graphics.drawable.Drawable; 
import android.os.Bundle; 
import android.os.Environment; 
import android.support.v7.app.ActionBarActivity; 

import com.squareup.picasso.Picasso; 
import com.squareup.picasso.Target; 

public class MainActivity extends ActionBarActivity { 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.image_download); 

     // 
     try { 

      URL url = new URL(
        "https://www.dropbox.com/s/s70xckuxjh5sbtw/pop.txt"); 

      // read text returned by server 
      BufferedReader in = new BufferedReader(new InputStreamReader(
        url.openStream())); 

      String currentUrl; 
      while ((currentUrl = in.readLine()) != null) { 
       System.out.println(currentUrl); 
      } 
      in.close(); 

     } catch (MalformedURLException e) { 
      System.out.println("Malformed URL: " + e.getMessage()); 
     } catch (IOException e) { 
      System.out.println("I/O Error: " + e.getMessage()); 
     } 
     // 

     Picasso.with(this).load(currentUrl).into(target); 

    } 

    private Target target = new Target() { 
     @Override 
     public void onBitmapLoaded(final Bitmap bitmap, Picasso.LoadedFrom from) { 
      new Thread(new Runnable() { 
       @Override 
       public void run() { 

        String fileName = currentUrl.substring(
          currentUrl.lastIndexOf('/') + 1, 
          currentUrl.length()); 

        String fname = "/image-" + fileName + ".jpg"; 

        File file = new File(Environment 
          .getExternalStorageDirectory().getPath() + fname); 
        if (file.exists()) 
         file.delete(); 
        try { 
         file.createNewFile(); 
         FileOutputStream ostream = new FileOutputStream(file); 
         bitmap.compress(CompressFormat.JPEG, 100, ostream); 
         ostream.close(); 
        } catch (Exception e) { 
         e.printStackTrace(); 
        } 

       } 
      }).start(); 
     } 

     @Override 
     public void onBitmapFailed(Drawable errorDrawable) { 
     } 

     @Override 
     public void onPrepareLoad(Drawable placeHolderDrawable) { 
      if (placeHolderDrawable != null) { 
      } 
     } 
    }; 

} 

이 내 코드는

Description Resource Path Location Type 
currentUrl cannot be resolved to a variable MainActivity.java /Copy of ImageDownloadSample/src/com/example/imagedownloadsample line 51 Java Problem 
currentUrl cannot be resolved MainActivity.java /Copy of ImageDownloadSample/src/com/example/imagedownloadsample line 62 Java Problem 
currentUrl cannot be resolved MainActivity.java /Copy of ImageDownloadSample/src/com/example/imagedownloadsample line 64 Java Problem 
currentUrl cannot be resolved MainActivity.java /Copy of ImageDownloadSample/src/com/example/imagedownloadsample line 63 Java Problem 

입니다

................................................. .................................................. .................................................. ................

Answer 1

내가 알 수있는 한 currentUrl은 실제로는 아닙니다. 목표에 정의됩니다.

String fileName = currentUrl.substring(
          currentUrl.lastIndexOf('/') + 1, 
          currentUrl.length()); 

여기서 currentUrl은 어디에 정의되어 있습니까? 그것은 onCreate에서 정의 된 것처럼 보이지만 다른 곳에서는 정의되지 않은 것 같습니다.

Answer 2

간단한 Java 범위 문제입니다. 변수는 try 안에 onCreate()으로 표시되어 있으므로 그 안에 try 블록 만 액세스 할 수 있습니다.

다른 영역에서 사용하려면 멤버 변수로 선언해야합니다.

//declare it here 
String currentUrl = ""; 

public class MainActivity extends ActionBarActivity { 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.image_download); 

    // 
    try { 

     URL url = new URL(
       "https://www.dropbox.com/s/s70xckuxjh5sbtw/pop.txt"); 

     // read text returned by server 
     BufferedReader in = new BufferedReader(new InputStreamReader(
       url.openStream())); 

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