Android NullPointerException에서 이미지를 선택 하시겠습니까?

Question

저는 현재 사용자가 갤러리에서 이미지를 그림으로 만들고 서버에 업로드 할 수있는 응용 프로그램을 만들려고합니다. 그러나 나는 여전히 이미지를 고르는데 골머리를 앓고있다. 튜토리얼을 정확히 따라 갔지만 활동을 시작할 때 NullPointer를 얻습니다.

너희들은 어떤 오류가 있습니까?

미리 감사드립니다.

Heres the code;

package de.arvidg.exampleactionbartabs; 

import android.app.Activity; 
import android.content.Intent; 
import android.database.Cursor; 
import android.graphics.BitmapFactory; 
import android.net.Uri; 
import android.os.Bundle; 
import android.provider.MediaStore; 
import android.view.View; 
import android.widget.Button; 
import android.widget.ImageView; 


public class UploadPicture extends Activity { 

    private static int RESULT_LOAD_IMAGE = 1; 

    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.main); 

     Button buttonLoadImage = (Button) findViewById(R.id.choosepic2); 
     buttonLoadImage.setOnClickListener(new View.OnClickListener() { 

      @Override 
      public void onClick(View arg0) { 

       Intent i = new Intent(
         Intent.ACTION_PICK, 
         android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI); 

       startActivityForResult(i, RESULT_LOAD_IMAGE); 
      } 
     }); 
    } 


    @Override 
    protected void onActivityResult(int requestCode, int resultCode, Intent data) { 
     super.onActivityResult(requestCode, resultCode, data); 

     if (requestCode == RESULT_LOAD_IMAGE && resultCode == RESULT_OK && null != data) { 
      Uri selectedImage = data.getData(); 
      String[] filePathColumn = { MediaStore.Images.Media.DATA }; 

      Cursor cursor = getContentResolver().query(selectedImage, 
        filePathColumn, null, null, null); 
      cursor.moveToFirst(); 

      int columnIndex = cursor.getColumnIndex(filePathColumn[0]); 
      String picturePath = cursor.getString(columnIndex); 
      cursor.close(); 

      ImageView imageView = (ImageView) findViewById(R.id.chosenPicView); 
      imageView.setImageBitmap(BitmapFactory.decodeFile(picturePath)); 

     } 


    } 
} 

로그 캣 :

03-17 10:56:35.470: W/dalvikvm(12169): threadid=1: thread exiting with uncaught exception (group=0x41e64300) 
03-17 10:56:35.480: E/AndroidRuntime(12169): FATAL EXCEPTION: main 
03-17 10:56:35.480: E/AndroidRuntime(12169): java.lang.RuntimeException: Unable to start activity ComponentInfo{de.arvidg.exampleactionbartabs/de.arvidg.exampleactionbartabs.UploadPicture}: java.lang.NullPointerException 
03-17 10:56:35.480: E/AndroidRuntime(12169): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2190) 
03-17 10:56:35.480: E/AndroidRuntime(12169): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2215) 
03-17 10:56:35.480: E/AndroidRuntime(12169): at android.app.ActivityThread.access$600(ActivityThread.java:145) 
03-17 10:56:35.480: E/AndroidRuntime(12169): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1211) 
03-17 10:56:35.480: E/AndroidRuntime(12169): at android.os.Handler.dispatchMessage(Handler.java:99) 
03-17 10:56:35.480: E/AndroidRuntime(12169): at android.os.Looper.loop(Looper.java:137) 
03-17 10:56:35.480: E/AndroidRuntime(12169): at android.app.ActivityThread.main(ActivityThread.java:4978) 
03-17 10:56:35.480: E/AndroidRuntime(12169): at java.lang.reflect.Method.invokeNative(Native Method) 
03-17 10:56:35.480: E/AndroidRuntime(12169): at java.lang.reflect.Method.invoke(Method.java:511) 
03-17 10:56:35.480: E/AndroidRuntime(12169): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791) 
03-17 10:56:35.480: E/AndroidRuntime(12169): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:558) 
03-17 10:56:35.480: E/AndroidRuntime(12169): at dalvik.system.NativeStart.main(Native Method) 
03-17 10:56:35.480: E/AndroidRuntime(12169): Caused by: java.lang.NullPointerException 
03-17 10:56:35.480: E/AndroidRuntime(12169): at de.arvidg.exampleactionbartabs.UploadPicture.onCreate(UploadPicture.java:34) 
03-17 10:56:35.480: E/AndroidRuntime(12169): at android.app.Activity.performCreate(Activity.java:5008) 
03-17 10:56:35.480: E/AndroidRuntime(12169): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079) 
03-17 10:56:35.480: E/AndroidRuntime(12169): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144) 
03-17 10:56:35.480: E/AndroidRuntime(12169): ... 11 more 

main.xml에

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent" 
    android:layout_gravity="center" 
    android:orientation="vertical" > 

    <LinearLayout 
     android:id="@+id/fragment_container" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" > 

     <Button 
      android:id="@+id/selectpic" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:text="select Picture" /> 

     <ImageView 
      android:id="@+id/imageView1" 
      android:layout_width="wrap_content" 
      android:layout_height="225dp" 
      android:layout_weight="29.60" 
      android:src="@drawable/gradient_bg" /> 

     <TextView 
      android:id="@+id/chosenpic" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:layout_weight="2.94" 
      android:text="Large Text" 
      android:textAppearance="?android:attr/textAppearanceLarge" /> 

    </LinearLayout> 


</LinearLayout> 

라인 (34)은 그 진술의 마지막 브래킷

buttonLoadImage.setOnClickListener(new View.OnClickListener() { 

      @Override 
      public void onClick(View arg0) { 

       Intent i = new Intent(
         Intent.ACTION_PICK, 
         android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI); 

       startActivityForResult(i, RESULT_LOAD_IMAGE); 
      } 
     }); 

Answer 1

그냥 당신이 레이아웃 파일에 버튼의 ID를 변경하고 활동 코드에 그 변경 사항을 반영하지 않은 코드에서 어떤 시점에서

Button buttonLoadImage = (Button) findViewById(R.id.selectpic); 

에

Button buttonLoadImage = (Button) findViewById(R.id.choosepic2); 

변경 .

항상 ID를 두 번 확인하십시오.

Answer 2

귀하의 실수 내가 생입니다 너 앞에서 네. Button 및 ImageView의 잘못된 ID를 입력했습니다.

다음과 같이 레이아웃에서 지정한 ID로 버튼을 초기화하십시오. 버튼 ID를 R.id.selectpic으로 정의하십시오.

Button buttonLoadImage = (Button) findViewById(R.id.selectpic); 

그리고 당신의 ImageView ID R.id.imageView1 아래 R.id.chosenPicView 외에 같이 다음

ImageView imageView = (ImageView) findViewById(R.id.imageView1); 

그리고 시도.