无法启动活动ComponentInfo;试图创建启动画面

时间:2013-10-16 23:34:37

标签: java android nullpointerexception splash-screen

我最近在我的Android应用程序中添加了一个启动画面以掩盖JSON文件的加载,但是我的应用程序在完成解析后崩溃了。我已经注释掉了代码并取消注释了代码,直到找到了有问题的段,但我不确定它为什么不起作用。

如果我从此代码段注释掉for循环,则代码可以正常工作。

来自MagazinePagesActivity.java:

public void loadItems() { 
    for (Item item : SplashActivity.downloadedItems) { 
        Post post = (Post) item;
        for (String tag : post.tags) {
            if (tag.equals(this.tag)) {
                // loader.loadImage(magazine.imageURL, new
                // SimpleImageLoadingListener());
                Bundle bundle = new Bundle();
                bundle.putString("title", post.title);
                bundle.putString("article", post.article);
                bundle.putString("imageURL", post.imageURL);
                MagazineFragment cover = new MagazineFragment();
                cover.setArguments(bundle);
                coverAdapter.addNewItem(cover);
            } 
        } 
    } 
    setContentView(vp);
}

起初,我认为这是因为没有正确定义SplashActivity.downloadedItems,但它对我来说很好看:

来自SplashActivity.java:

public static ArrayList<Item> downloadedItems = new ArrayList<Item>();

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

    new RetreiveJSONTask() {


        protected void onPostExecute(String JSON)
        {
            Log.d("SplashActivity", "Beginning parsingJSON" );
            downloadedItems = parseJSON ( JSON );
            Log.d("SplashActivity", "Finished parsingJSON" );
            Log.d("SplashActivity", "" + SplashActivity.downloadedItems.isEmpty());
            Intent i = new Intent(SplashActivity.this, MagazinePagesActivity.class);
            startActivity(i);

            // Closes the splash screen
            finish();
        }
    }.execute(sourceURL());
}

来自LogCat:

10-16 19:23:12.602: D/AndroidRuntime(828): Shutting down VM
10-16 19:23:12.602: W/dalvikvm(828): threadid=1: thread exiting with uncaught exception (group=0x41465700)
10-16 19:23:12.632: E/AndroidRuntime(828): FATAL EXCEPTION: main
10-16 19:23:12.632: E/AndroidRuntime(828): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.bruinfootball/com.dailybruin.bruinframework.channels.StoryListActivity}: java.lang.NullPointerException
10-16 19:23:12.632: E/AndroidRuntime(828):  at     android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2211)
10-16 19:23:12.632: E/AndroidRuntime(828):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
10-16 19:23:12.632: E/AndroidRuntime(828):  at android.app.ActivityThread.access$600(ActivityThread.java:141)
10-16 19:23:12.632: E/AndroidRuntime(828):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
10-16 19:23:12.632: E/AndroidRuntime(828):  at android.os.Handler.dispatchMessage(Handler.java:99)
10-16 19:23:12.632: E/AndroidRuntime(828):  at android.os.Looper.loop(Looper.java:137)
10-16 19:23:12.632: E/AndroidRuntime(828):  at android.app.ActivityThread.main(ActivityThread.java:5103)
10-16 19:23:12.632: E/AndroidRuntime(828):  at java.lang.reflect.Method.invokeNative(Native Method)
10-16 19:23:12.632: E/AndroidRuntime(828):  at java.lang.reflect.Method.invoke(Method.java:525)
10-16 19:23:12.632: E/AndroidRuntime(828):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
10-16 19:23:12.632: E/AndroidRuntime(828):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
10-16 19:23:12.632: E/AndroidRuntime(828):  at dalvik.system.NativeStart.main(Native Method)
10-16 19:23:12.632: E/AndroidRuntime(828): Caused by: java.lang.NullPointerException
10-16 19:23:12.632: E/AndroidRuntime(828):  at com.dailybruin.bruinframework.channels.StoryListActivity.loadItems(StoryListActivity.java:27)
10-16 19:23:12.632: E/AndroidRuntime(828):  at com.dailybruin.bruinframework.channels.JSONItemsActivity.onCreate(JSONItemsActivity.java:20)
10-16 19:23:12.632: E/AndroidRuntime(828):  at com.dailybruin.bruinframework.channels.StoryItemsActivity.onCreate(StoryItemsActivity.java:18)
10-16 19:23:12.632: E/AndroidRuntime(828):  at com.dailybruin.bruinframework.channels.StoryListActivity.onCreate(StoryListActivity.java:18)
10-16 19:23:12.632: E/AndroidRuntime(828):  at android.app.Activity.performCreate(Activity.java:5133)
10-16 19:23:12.632: E/AndroidRuntime(828):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
10-16 19:23:12.632: E/AndroidRuntime(828):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2175)
10-16 19:23:12.632: E/AndroidRuntime(828):  ... 11 more

不确定它是否有帮助,但SplashActivity和MagazinePagesActivity分别扩展了JSONItemsActivity。

提前感谢您的帮助!我对Android很新,所以请耐心等待。

编辑:这很奇怪,我用来检查ArrayList是否为空的调试语句返回true,但是parseJSON中的另一个调试语句显示正在添加内容。我的parseJSON方法:

public ArrayList<Item> parseJSON(String jsonString) {
    ArrayList<Item> magazines = new ArrayList<Item>();
    JSONArray jArray;
    try {
        jArray = new JSONArray(jsonString);

        JSONObject jObject;
        JSONObject image;
        String img;
        String title;
        String subtitle;
        int commentCount;
        String content;
        String date;
        String ID;
        String slug;
        JSONArray array;
        String[] tags;
        for (int i = 0; i < jArray.length(); i++) {
            jObject = jArray.getJSONObject(i);
            img = jObject.getString("tall_image_url");
            if (img.equals(""))
                img = jObject.getString("image_url");
            if (img.equals("") && !jObject.isNull("poster_image")) {
                image = jObject.getJSONObject("poster_image");
                img = image.getString("name");
            }
            title = jObject.getString("title");
            subtitle = jObject.getString("subtitle");
            commentCount = jObject.getInt("comment_count");
            content = jObject.getString("content_html");
            date = jObject.getString("creation_date");
            ID = jObject.getString("id");
            slug = jObject.getString("slug");
            array = jObject.getJSONArray("tags_list");
            tags = new String[array.length()];
            for (int j = 0; j < array.length(); j++) {
                tags[j] = array.getString(j);
            }

            for (String tag : tags) {
                if (tag.equals(this.tag))
                {
                    Post additive = new Post(img, title, subtitle,
                            commentCount, content, date, ID, slug, tags);
                    magazines.add(additive);
                    Log.d("SplashActivity", additive.toString());
                }
            }

        }

    } catch (JSONException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    return magazines;
}

StoryListActivity第27行:

public void loadItems() {
    (findViewById(R.id.progress_bar)).setVisibility(View.GONE);
    getSupportFragmentManager().beginTransaction()
    .replace(R.id.loading, new StoryListFragment()).commit();
}

StoryItemsActivity(MagazinePagesActivity和StoryListActivity扩展了这个类;这个类扩展了JSONItemsActivity,SplashActivity也扩展了它):

package com.dailybruin.bruinframework.channels;

import java.util.ArrayList;

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

import com.dailybruin.bruinframework.R;
import com.dailybruin.bruinframework.base.BaseActivity;
import com.dailybruin.bruinframework.base.URLBuilder;
import android.os.Bundle;

public abstract class StoryItemsActivity extends JSONItemsActivity {

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
}

public String sourceURL()
{
    return URLBuilder.getPostsURL(getString(R.string.slug));
}

public ArrayList<Item> parseJSON(String jsonString) {
    // Using pre-downloaded and parsed JSON
    return SplashActivity.downloadedItems;
}
}

1 个答案:

答案 0 :(得分:0)

检查这部分代码。第27行。这是空的,因此导致NPE。

Caused by: java.lang.NullPointerException 10-16 19:23:12.632: E/AndroidRuntime(828): at com.dailybruin.bruinframework.channels.StoryListActivity.loadItems(StoryListActivity.java:27)