Question

    package com.devinfotech.glind.activity;

import android.app.ProgressDialog;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.DefaultItemAnimator;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.View;

import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonArrayRequest;
import com.devinfotech.glind.R;
import com.devinfotech.glind.adapter.GalleryAdapter;
import com.devinfotech.glind.app.AppController;
import com.devinfotech.glind.model.Image;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

    private String TAG = MainActivity.class.getSimpleName();
    private static final String endpoint = "http://api.androidhive.info/json/glide.json";
    private ArrayList<Image> images;
    private ProgressDialog pDialog;
    private GalleryAdapter mAdapter;
    private RecyclerView recyclerView;

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

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        recyclerView = (RecyclerView) findViewById(R.id.recycler_view);

        pDialog = new ProgressDialog(this);
        images = new ArrayList<>();
        mAdapter = new GalleryAdapter(getApplicationContext(), images);

        RecyclerView.LayoutManager mLayoutManager = new GridLayoutManager(getApplicationContext(), 2);
        recyclerView.setLayoutManager(mLayoutManager);
        recyclerView.setItemAnimator(new DefaultItemAnimator());
        recyclerView.setAdapter(mAdapter);

         recyclerView.addOnItemTouchListener(new GalleryAdapter.RecyclerTouchListener(getApplicationContext(), recyclerView, new GalleryAdapter.ClickListener() {
            @Override
            public void onClick(View view, int position) {
                Bundle bundle = new Bundle();
                bundle.putSerializable("images", images);
                bundle.putInt("position", position);

                FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
                SlideshowDialogFragment newFragment = SlideshowDialogFragment.newInstance();
                newFragment.setArguments(bundle);
                newFragment.show(ft, "slideshow");
            }

            @Override
            public void onLongClick(View view, int position) {

            }
        }));

        fetchImages();
    }

    private void fetchImages() {

        pDialog.setMessage("Downloading json...");
        pDialog.show();

        JsonArrayRequest req = new JsonArrayRequest(endpoint,
                new Response.Listener<JSONArray>() {
                    @Override
                    public void onResponse(JSONArray response) {
                        Log.d(TAG, response.toString());
                        pDialog.hide();

                        images.clear();
                        for (int i = 0; i < response.length(); i++) {
                            try {
                                JSONObject object = response.getJSONObject(i);

                                Image image = new Image();
                                image.setName(object.getString("name"));

                                JSONObject url = object.getJSONObject("url");
                                image.setSmall(url.getString("small"));
                                image.setMedium(url.getString("medium"));
                                image.setLarge(url.getString("large"));
                                image.setTimestamp(object.getString("timestamp"));

                                images.add(image);

                            } catch (JSONException e) {
                                Log.e(TAG, "Json parsing error: " + e.getMessage());
                            }
                        }

                        mAdapter.notifyDataSetChanged();
                    }
                }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                Log.e(TAG, "Error: " + error.getMessage());
                pDialog.hide();
            }
        });

        // Adding request to request queue
        AppController.getInstance()
                .addToRequestQueue(req);
    }
}

    package com.devinfotech.glind.app;

import android.app.Application;
import android.text.TextUtils;

import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.toolbox.Volley;

/**
 * Created by Lincoln on 04/04/16.
 */
public class AppController extends Application {

    public static final String TAG = AppController.class
            .getSimpleName();

    private RequestQueue mRequestQueue;

    private static AppController mInstance;

    @Override
    public void onCreate() {
        super.onCreate();
        mInstance = this;
    }

    public static synchronized AppController getInstance() {
        return mInstance;
    }

    public RequestQueue getRequestQueue() {
        if (mRequestQueue == null) {
            mRequestQueue = Volley.newRequestQueue(getApplicationContext());
        }

        return mRequestQueue;
    }

    public <T> void addToRequestQueue(Request<T> req, String tag) {
        // set the default tag if tag is empty
        req.setTag(TextUtils.isEmpty(tag) ? TAG : tag);
        getRequestQueue().add(req);
    }

    public <T> void addToRequestQueue(Request<T> req) {
        req.setTag(TAG);
        getRequestQueue().add(req);
    }

    public void cancelPendingRequests(Object tag) {
        if (mRequestQueue != null) {
            mRequestQueue.cancelAll(tag);
        }
    }
}

错误：

10-10 13：01：02.030 23482-23482 /？ E / dalvikvm：无法将符号链接/存储/内部添加到/ storage / emulated / legacy：文件存在 10-10 13：01：02.210 23482-23482 / com.devinfotech.glind E / dalvikvm：找不到类'android.graphics.drawable.RippleDrawable'，从方法android.support.v7.widget.AppCompatImageHelper.hasOverlappingRendering中引用 10-10 13：01：02.300 23482-23482 /？ E / AndroidRuntime：致命异常：主要过程：com.devinfotech.glind，PID：23482 java.lang.RuntimeException：无法启动活动ComponentInfo {com.devinfotech.glind / com.devinfotech.glind.activity.MainActivity}：java.lang.NullPointerException 在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2299）在android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:2349）在android.app.ActivityThread.access $ 800（ActivityThread.java:151）在android.app.ActivityThread $ H.handleMessage（ActivityThread.java:1243）在android.os.Handler.dispatchMessage（Handler.java:102）在android.os.Looper.loop（Looper.java:136）在android.app.ActivityThread.main（ActivityThread.java:5372） at java.lang.reflect.Method.invokeNative（Native Method）在java.lang.reflect.Method.invoke（Method.java:515）在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:970）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:786） at dalvik.system.NativeStart.main（Native Method）引起：java.lang.NullPointerException 在com.devinfotech.glind.activity.MainActivity.fetchImages（MainActivity.java:123）在com.devinfotech.glind.activity.MainActivity.onCreate（MainActivity.java:75）在android.app.Activity.performCreate（Activity.java:5258）在android.app.Instrumentation.callActivityOnCreate（Instrumentation.java:1099）在android.app.ActivityThread.performLaunchActivity（ActivityThread.java:2239）在android.app.ActivityThread.handleLaunchActivity（ActivityThread.java:2349）在android.app.ActivityThread.access $ 800（ActivityThread.java:151）在android.app.ActivityThread $ H.handleMessage（ActivityThread.java:1243）在android.os.Handler.dispatchMessage（Handler.java:102）在android.os.Looper.loop（Looper.java:136）在android.app.ActivityThread.main（ActivityThread.java:5372） at java.lang.reflect.Method.invokeNative（Native Method）在java.lang.reflect.Method.invoke（Method.java:515）在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:970）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:786）在dalvik.system.NativeStart.main（本地方法）

在纹波可绘制上获得错误

0 个答案: