android-动态的惰性列表

概述大家好,我想使thisLazylist动态化.我首先尝试过使用图像,但是用力将其关闭.如果我的方法错误,请指导.这是代码publicclassTestextendsActivity{ListViewlist;LazyAdapteradapter;privateString[]mStrings;@OverridepublicvoidonCreate(Bu

大家好,我想使this LazyList动态化.我首先尝试过使用图像,但是用力将其关闭.如果我的方法错误,请指导.
这是代码

public class Test extends Activity {    ListVIEw List;    LazyAdapter adapter;    private String[] mStrings;    @OverrIDe    public voID onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentVIEw(R.layout.main);        ArrayList<String> ListItems = new ArrayList<String>();        try {            URL twitter = new URL(                    "http://mIDsweden.gofreeserve.com/proj/androIDJson.PHP?IDentifIEr=123");            URLConnection tc = twitter.openConnection();            BufferedReader in = new BufferedReader(new inputStreamReader(                    tc.getinputStream()));            String line;            while ((line = in.readline()) != null) {                JsONArray ja = new JsONArray(line);                for (int i = 0; i < ja.length(); i++) {                    JsONObject jo = (JsONObject) ja.get(i);                    ListItems.add(jo.getString("http://mIDsweden.gofreeserve.com/proj/admin/pictures/file87619.jpg"));                }            }        } catch (MalformedURLException e) {            // Todo auto-generated catch block            e.printstacktrace();         } catch (IOException e) {            // Todo auto-generated catch block            e.printstacktrace();        } catch (JsONException e) {            // Todo auto-generated catch block            e.printstacktrace();        }        mStrings = ListItems.toArray(new String[ListItems.size()]);         List=(ListVIEw)findVIEwByID(R.ID.List);        adapter=new LazyAdapter(this, mStrings);         List.setAdapter(adapter);         button b=(button)findVIEwByID(R.ID.button1);         b.setonClickListener(Listener);        }    @OverrIDe    public voID onDestroy()    {        adapter.imageLoader.stopThread();        List.setAdapter(null);        super.onDestroy();    }    public OnClickListener Listener=new OnClickListener(){        public voID onClick(VIEw arg0) {            adapter.imageLoader.clearCache();            adapter.notifyDataSetChanged();        }    };}

logcat的

07-09 01:00:51.825: WARN/dalvikvm(12674): threadID=3: thread exiting with uncaught exception (group=0x4001e390)07-09 01:00:51.835: ERROR/AndroIDRuntime(12674): Uncaught handler: thread main exiting due to uncaught exception07-09 01:00:51.865: ERROR/AndroIDRuntime(12674): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.droIDnova.androID.howto.optionmenu/com.droIDnova.androID.howto.optionmenu.Test}: java.lang.NullPointerException07-09 01:00:51.865: ERROR/AndroIDRuntime(12674):     at androID.app.ActivityThread.performlaunchActivity(ActivityThread.java:2596)07-09 01:00:51.865: ERROR/AndroIDRuntime(12674):     at androID.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2621)07-09 01:00:51.865: ERROR/AndroIDRuntime(12674):     at androID.app.ActivityThread.access00(ActivityThread.java:126)07-09 01:00:51.865: ERROR/AndroIDRuntime(12674):     at androID.app.ActivityThread$H.handleMessage(ActivityThread.java:1932)07-09 01:00:51.865: ERROR/AndroIDRuntime(12674):     at androID.os.Handler.dispatchMessage(Handler.java:99)07-09 01:00:51.865: ERROR/AndroIDRuntime(12674):     at androID.os.Looper.loop(Looper.java:123)07-09 01:00:51.865: ERROR/AndroIDRuntime(12674):     at androID.app.ActivityThread.main(ActivityThread.java:4595)07-09 01:00:51.865: ERROR/AndroIDRuntime(12674):     at java.lang.reflect.Method.invokeNative(Native Method)07-09 01:00:51.865: ERROR/AndroIDRuntime(12674):     at java.lang.reflect.Method.invoke(Method.java:521)07-09 01:00:51.865: ERROR/AndroIDRuntime(12674):     at com.androID.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)07-09 01:00:51.865: ERROR/AndroIDRuntime(12674):     at com.androID.internal.os.ZygoteInit.main(ZygoteInit.java:618)07-09 01:00:51.865: ERROR/AndroIDRuntime(12674):     at dalvik.system.NativeStart.main(Native Method)07-09 01:00:51.865: ERROR/AndroIDRuntime(12674): Caused by: java.lang.NullPointerException07-09 01:00:51.865: ERROR/AndroIDRuntime(12674):     at com.droIDnova.androID.howto.optionmenu.LazyAdapter.getCount(LazyAdapter.java:27)07-09 01:00:51.865: ERROR/AndroIDRuntime(12674):     at androID.Widget.ListVIEw.setAdapter(ListVIEw.java:431)07-09 01:00:51.865: ERROR/AndroIDRuntime(12674):     at com.droIDnova.androID.howto.optionmenu.Test.onCreate(Test.java:35)07-09 01:00:51.865: ERROR/AndroIDRuntime(12674):     at androID.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)07-09 01:00:51.865: ERROR/AndroIDRuntime(12674):     at androID.app.ActivityThread.performlaunchActivity(ActivityThread.java:2544)07-09 01:00:51.865: ERROR/AndroIDRuntime(12674):     ... 11 more07-09 01:00:51.895: INFO/Process(82): Sending signal. PID: 12674 SIG: 307-09 01:00:51.895: INFO/dalvikvm(12674): threadID=7: reacting to signal 3

解决方法:

您的NullPointer异常在getCount()第27行中：

Caused by: java.lang.NullPointerExceptionat com.droIDnova.androID.howto.optionmenu.LazyAdapter.getCount(LazyAdapter.java:27)

您可以通过将getCount()更改为以下内容来修复症状：

public int getCount() {    if(data != null){        return data.length;    }    return 0;}

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