我是一个新的Android我想制作一个Documents Scanner应用程序。所以我用作裁剪功能GitHub库知道我想在列表View上显示裁剪图像。为此，我也使用github上的通用图像加载器库，但仍然出现错误。这个库我把它放在一个libs文件夹
请给我一些简单的解决方案
这里我的主要活动是
public class MainActivity extends AppCompatActivity {
Button btn;
Context context = this;
public static final int REQUEST_Code = 99;
ImageView mImageView;
int prefrences = ScanConstants.OPEN_CAMERA;
ListView mListView;
ArrayAdapter<String > images_adapter;
ImageLoader imageLoader;
ArrayList images_Uri;
DisplayImageOptions options;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mListView= (ListView) findViewById(R.id.mListView);
btn = (Button) findViewById(R.id.button);
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
showdialogebox();
}
});
}
private void showdialogebox() {
AlertDialog.Builder builder = new AlertDialog.Builder(context);
builder.setTitle("Take Phote");
final String item[] = {"Take form cam", "Take form file"};
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.select_dialog_item, item);
AlertDialog.Builder builder1 = builder.setAdapter(adapter, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
if (which == 0) {
Intent intent = new Intent(getApplicationContext(), ScanActivity.class);
intent.putExtra(ScanConstants.OPEN_INTENT_PREFERENCE, prefrences);
startActivityForResult(intent, REQUEST_Code);
}
}
});
builder.show();
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
Uri uri = data.getExtras().getParcelable(ScanConstants.SCANNED_RESULT);
getContentResolver().delete(uri, null, null);
images_Uri.add(uri);
Image_Adapter adapter=new Image_Adapter(getApplicationContext(),R.layout.single_image_view,images_Uri);
mListView.setAdapter(adapter);
}
}
这是我的Image_Adapter类代码
public class Image_Adapter extends ArrayAdapter<ViewHolderImage> {
Context context;
int resourceid;
public final static String IMAGE_PATH = Environment
.getExternalStorageDirectory().getPath() + "/scanSample";
ArrayList images=null;
public Image_Adapter(Context context, int resource, ArrayList images) {
super(context,resource,images);
this.context=context;
this.resourceid=resource;
this.images=images;
}
ViewHolderImage holderImage=null;
@NonNull
@Override
public View getView(int position, View convertView, ViewGroup parent) {
if (convertView==null){
LayoutInflater inflater=((Activity)context).getLayoutInflater();
convertView=inflater.inflate(resourceid,parent,false);
holderImage=new ViewHolderImage();
holderImage.imageView=(ImageView)convertView.findViewById(R.id.mImageView);
convertView.setTag(holderImage);
}else
{
holderImage=(ViewHolderImage)convertView.getTag();
}
holderImage.imageView.setMaxWidth(100);
holderImage.imageView.setMaxWidth(100);
ImageLoader imageLoader =null;
imageLoader.displayImage(IMAGE_PATH,holderImage.imageView);
return convertView;
}
}
ViewHolderImage类代码
enter code here
public class ViewHolderImage {
ImageView imageView;
}
这是日志猫的错误显示`
>>>> Normal User
11-24 22:22:11.180 25628-25628/com.example.hassanjan.documentsscannerapp1 E/dalvikvm: >>>>> com.example.hassanjan.documentsscannerapp1 [ userId:0 | appId:10236 ]
11-24 22:22:11.490 25628-25628/com.example.hassanjan.documentsscannerapp1 E/InstantRun: Could not find slices in APK; aborting.
11-24 22:22:11.720 25628-25628/com.example.hassanjan.documentsscannerapp1 E/dalvikvm: Could not find class 'android.graphics.drawable.RippleDrawable', referenced from method android.support.v7.widget.AppCompatImageHelper.hasOverlappingRendering
11-24 22:22:16.906 25628-25628/com.example.hassanjan.documentsscannerapp1 E/ViewRootImpl: sendUserActionEvent() mView == null
11-24 22:22:33.664 25628-25628/com.example.hassanjan.documentsscannerapp1 E/ViewRootImpl: sendUserActionEvent() mView == null
11-24 22:22:42.223 25628-25628/com.example.hassanjan.documentsscannerapp1 E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.hassanjan.documentsscannerapp1, PID: 25628 java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=99, result=-1, data=Intent { (has extras) }} to activity {com.example.hassanjan.documentsscannerapp1/com.example.hassanjan.documentsscannerapp1.MainActivity}: java.lang.NullPointerException
at android.app.ActivityThread.deliverResults(ActivityThread.java:3580)
at android.app.ActivityThread.handleSendResult(ActivityThread.java:3623)
at android.app.ActivityThread.access$1400(ActivityThread.java:169)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1328)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:146)
at android.app.ActivityThread.main(ActivityThread.java:5487)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099)
dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.example.hassanjan.documentsscannerapp1.MainActivity.onActivityResult(MainActivity.java:114)
at android.app.Activity.dispatchActivityResult(Activity.java:5643)
at android.app.ActivityThread.deliverResults(ActivityThread.java:3576)
at android.app.ActivityThread.handleSendResult(ActivityThread.java:3623)
at android.app.ActivityThread.access$1400(ActivityThread.java:169)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1328)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:146)
at android.app.ActivityThread.main(ActivityThread.java:5487)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099)
at dalvik.system.NativeStart.main(Native Method)
**主要活动**上的Hassanjan114错误显示
images_Uri.add(uri);
答案 0 :(得分：1)
您可以在listview中设置图像，这样就可以在您的gradel文件中添加compile 'com.github.bumptech.glide:glide:3.7.0'，这是我用来将图片视图添加到列表视图的一段代码
ImageView circleImageView = (ImageView) view.findViewById(R.id.profile_image);
Mediafileinfo mediafileinfo =(Mediafileinfo)getItem(position);
Glide.with(getContext()).load(mediafileinfo.getAlbum_art_uri())
.thumbnail(1f)
.crossFade()
.override(50,50) //(the size of the image)
.placeholder(R.drawable.music)
.diskCacheStrategy(DiskCacheStrategy.SOURCE)
.into(circleImageView);
以下是制作自定义列表视图link
的教程