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我的应用是当用户单击 botton 时。它将在图库或其他应用程序中显示图像，当用户从图库中选择图像然后显示用户选择的图像形式

我ImagePath用方法找到FindPath()

"String imagePath = findPath(imageUri);" 
return type String .

然后我用

"Bitmap imageData = BitmapFactory.decodeFile(imagePath); 
 image.setImageBitmap(imageData);"

这是我的 runtimeError 我认为这是关于显示图像的错误

 08-27 04:42:24.815: E/AndroidRuntime(1789): FATAL EXCEPTION: main
 08-27 04:42:24.815: E/AndroidRuntime(1789): java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=1, result=-1, data=Intent { dat=content://media/external/images/media/13 }} to activity {com.example.gallerymagazine/com.example.gallerymagazine.MainActivity}: java.lang.NullPointerException
08-27 04:42:24.815: E/AndroidRuntime(1789):     at     android.app.ActivityThread.deliverResults(ActivityThread.java:3319)
08-27 04:42:24.815: E/AndroidRuntime(1789):     at android.app.ActivityThread.handleSendResult(ActivityThread.java:3362)
08-27 04:42:24.815: E/AndroidRuntime(1789):     at android.app.ActivityThread.access$1100(ActivityThread.java:141)
08-27 04:42:24.815: E/AndroidRuntime(1789):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1282)
08-27 04:42:24.815: E/AndroidRuntime(1789):     at android.os.Handler.dispatchMessage(Handler.java:99)
08-27 04:42:24.815: E/AndroidRuntime(1789):     at android.os.Looper.loop(Looper.java:137)
08-27 04:42:24.815: E/AndroidRuntime(1789):     at android.app.ActivityThread.main(ActivityThread.java:5041)
08-27 04:42:24.815: E/AndroidRuntime(1789):     at java.lang.reflect.Method.invokeNative(Native Method)
08-27 04:42:24.815: E/AndroidRuntime(1789):     at java.lang.reflect.Method.invoke(Method.java:511)
08-27 04:42:24.815: E/AndroidRuntime(1789):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
08-27 04:42:24.815: E/AndroidRuntime(1789):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
08-27 04:42:24.815: E/AndroidRuntime(1789):     at dalvik.system.NativeStart.main(Native Method)
08-27 04:42:24.815: E/AndroidRuntime(1789): Caused by: java.lang.NullPointerException
08-27 04:42:24.815: E/AndroidRuntime(1789):     at com.example.gallerymagazine.MainActivity.onActivityResult(MainActivity.java:62)
08-27 04:42:24.815: E/AndroidRuntime(1789):     at android.app.Activity.dispatchActivityResult(Activity.java:5293)
08-27 04:42:24.815: E/AndroidRuntime(1789):     at android.app.ActivityThread.deliverResults(ActivityThread.java:3315)
08-27 04:42:24.815: E/AndroidRuntime(1789):     ... 11 more

这是我的代码

package com.example.gallerymagazine;

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

public class MainActivity extends Activity {
private static final int browse_image = 1;
private TextView text;
private Button browse;
private ImageView image;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    TextView text = (TextView) findViewById(R.id.text);
    ImageView image = (ImageView) findViewById(R.id.image);
    Button browse = (Button) findViewById(R.id.browse_image_button);

    browse.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            Intent intent = new Intent();
            intent.setAction(Intent.ACTION_GET_CONTENT);
            intent.setType("image/*");
            startActivityForResult(Intent.createChooser(intent, "select app to pick image"),browse_image);
        }
    });


}
protected void onActivityResult(int requestCode, int resultCode, Intent returnedIntent){
    super.onActivityResult(requestCode, resultCode, returnedIntent);
    switch (requestCode){
    case browse_image:
    if(resultCode != RESULT_CANCELED){
        if(resultCode == RESULT_OK){
            // เมือคลิกที่รูป ข้อมูลจะถูกส่งผ่านพารามิเตอร์ returnedIntent โดยมีผลลัพธ์เป็น URI(ฝช้ในการหาไฟล์พาด)
            Uri imageUri = returnedIntent.getData();
            String msg = "URL::"+imageUri+"\n";
            // นำURI หาpath 
            String imagePath = findPath(imageUri);
            msg += "Path::"+imagePath;

            Log.i("Path",imagePath);
            // นำpath ไปดึงรูปมาแสดง
            Bitmap imageData = BitmapFactory.decodeFile(imagePath);
            image.setImageBitmap(imageData);
        }
    }else{
            Log.e("ERROR","error happened");
        }
    }
}

// method find path
private String findPath(Uri imageUri) {
    // TODO Auto-generated method stub
    String imagePath;
    String[] columns = {MediaStore.Images.Media.DATA};
    Cursor cursor = getContentResolver().query(imageUri, columns, null, null, null);
    //จาก Gallery
    if(cursor != null){

        int columnIndex = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
        cursor.moveToFirst();
        imagePath = cursor.getString(columnIndex);
    //อื่นๆ
    }else{
        imagePath = imageUri.getPath();
    }
    return imagePath;
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

}

这是我的布局显示

  <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<Button
    android:id="@+id/browse_image_button"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="Browse Image"/>



<TextView
    android:id="@+id/text"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@+id/browse_image_button"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="44dp"
    android:text="TextView" />

<ImageView
    android:id="@+id/image"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerHorizontal="true"
    android:layout_centerVertical="true"
    android:src="@drawable/ic_launcher" />

 </RelativeLayout>

请检查一下，非常感谢

4

1 回答 1

1

在你的 onCreate 方法中改变这个：

    TextView text = (TextView) findViewById(R.id.text);
    ImageView image = (ImageView) findViewById(R.id.image);
    Button browse = (Button) findViewById(R.id.browse_image_button);

对此：

 text = (TextView) findViewById(R.id.text);
 image = (ImageView) findViewById(R.id.image);
 browse = (Button) findViewById(R.id.browse_image_button);

原因是当你这样做时

TextView text = (TextView) findViewById(R.id.text);

您正在定义一个不能被其他方法访问的局部变量。因此，当您尝试引用它时，您会得到一个空指针异常。

于 2013-08-27T05:02:21.057 回答