大家好我想打this Lazylist动态。我曾试图与图片第一击打其用武力来关闭。请指导如果我的做法是错误的。 这里是code
公共类测试延伸活动{
ListView控件列表;
LazyAdapter适配器;
私有String [] mStrings;
@覆盖
公共无效的onCreate(包savedInstanceState){
super.onCreate(savedInstanceState);
的setContentView(R.layout.main);
ArrayList的<字符串> listItems中的=新的ArrayList<字符串>();
尝试 {
网址叽叽喳喳=新的URL(
http://midsweden.gofreeserve.com/proj/androidjson.php?identifier=123);
的URLConnection TC = twitter.openConnection();
的BufferedReader在=新的BufferedReader(新的InputStreamReader(
tc.getInputStream()));
串线;
而((行= in.readLine())!= NULL){
JSONArray JA =新JSONArray(线);
的for(int i = 0; I< ja.length();我++){
的JSONObject祚=(的JSONObject)ja.get(我);
listItems.add(jo.getString(http://midsweden.gofreeserve.com/proj/admin/pictures/file87619.jpg));
}
}
}赶上(MalformedURLException异常E){
// TODO自动生成的catch块
e.printStackTrace();
}赶上(IOException异常E){
// TODO自动生成的catch块
e.printStackTrace();
}赶上(JSONException E){
// TODO自动生成的catch块
e.printStackTrace();
}
mStrings = listItems.toArray(新的String [listItems.size());
名单=(ListView控件)findViewById(R.id.list);
适配器=新LazyAdapter(这一点,mStrings);
list.setAdapter(适配器);
按钮B =(按钮)findViewById(R.id.button1);
b.setOnClickListener(听众);
}
@覆盖
公共无效的onDestroy()
{
adapter.imageLoader.stopThread();
list.setAdapter(空);
super.onDestroy();
}
公共OnClickListener监听器=新OnClickListener(){
公共无效的onClick(查看为arg0){
adapter.imageLoader.clearCache();
adapter.notifyDataSetChanged();
}
};
}
logcat的
1月7日至九日:00:51.825:WARN / dalvikvm(12674):主题ID = 3:线程退出与未捕获的异常(组= 0x4001e390)
一月七日至九日:00:51.835:ERROR / AndroidRuntime(12674):未捕获的处理程序:螺纹主力退出,由于未捕获的异常
一月七日至九日:00:51.865:ERROR / AndroidRuntime(12674):java.lang.RuntimeException的:无法启动的活动ComponentInfo {com.droidnova.android.howto.optionmenu / com.droidnova.android.howto.optionmenu.Test} :显示java.lang.NullPointerException
一月七日至九日:00:51.865:ERROR / AndroidRuntime(12674):在android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2596)
一月七日至九日:00:51.865:ERROR / AndroidRuntime(12674):在android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2621)
一月七日至九日:00:51.865:ERROR / AndroidRuntime(12674):在android.app.ActivityThread.access $ 2200(ActivityThread.java:126)
一月七日至九日:00:51.865:ERROR / AndroidRuntime(12674):在android.app.ActivityThread $ H.handleMessage(ActivityThread.java:1932)
一月七日至九日:00:51.865:ERROR / AndroidRuntime(12674):在android.os.Handler.dispatchMessage(Handler.java:99)
一月七日至九日:00:51.865:ERROR / AndroidRuntime(12674):在android.os.Looper.loop(Looper.java:123)
一月七日至九日:00:51.865:ERROR / AndroidRuntime(12674):在android.app.ActivityThread.main(ActivityThread.java:4595)
一月七日至九日:00:51.865:ERROR / AndroidRuntime(12674):在java.lang.reflect.Method.invokeNative(本机方法)
一月七日至九日:00:51.865:ERROR / AndroidRuntime(12674):在java.lang.reflect.Method.invoke(Method.java:521)
一月七日至九日:00:51.865:ERROR / AndroidRuntime(12674):在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run(ZygoteInit.java:860)
一月七日至九日:00:51.865:ERROR / AndroidRuntime(12674):在com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
一月七日至九日:00:51.865:ERROR / AndroidRuntime(12674):在dalvik.system.NativeStart.main(本机方法)
一月七日至九日:00:51.865:ERROR / AndroidRuntime(12674):由:显示java.lang.NullPointerException
一月七日至九日:00:51.865:ERROR / AndroidRuntime(12674):在com.droidnova.android.howto.optionmenu.LazyAdapter.getCount(LazyAdapter.java:27)
一月七日至九日:00:51.865:ERROR / AndroidRuntime(12674):在android.widget.ListView.setAdapter(ListView.java:431)
一月七日至九日:00:51.865:ERROR / AndroidRuntime(12674):在com.droidnova.android.howto.optionmenu.Test.onCreate(Test.java:35)
一月七日至九日:00:51.865:ERROR / AndroidRuntime(12674):在android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
一月七日至九日:00:51.865:ERROR / AndroidRuntime(12674):在android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2544)
一月七日至九日:00:51.865:ERROR / AndroidRuntime(12674):11 ...更多
一月七日至九日:00:51.895:信息/工艺(82):发送信号。 PID:12674 SIG:3
七月九日01:00:51.895:信息/ dalvikvm(12674):主题ID = 7:反应以信号3
解决方案
您空指针异常是getCount将()第27行:
产生的原因:显示java.lang.NullPointerException
在com.droidnova.android.howto.optionmenu.LazyAdapter.getCount(LazyAdapter.java:27)
您可以通过改变getCount将()来解决这个sympton:
公众诠释getCount将(){
如果(数据!= NULL){
返回data.length;
}
返回0;
}
Hello everyone i want to make this Lazylist dynamic . i have tried with images first buts its coming with force to close . Please guide if my approach is wrong. Here is code
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
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 exception
07-09 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.NullPointerException
07-09 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.access$2200(ActivityThread.java:126)
07-09 01:00:51.865: ERROR/AndroidRuntime(12674): at android.app.ActivityThread$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.NullPointerException
07-09 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 more
07-09 01:00:51.895: INFO/Process(82): Sending signal. PID: 12674 SIG: 3
07-09 01:00:51.895: INFO/dalvikvm(12674): threadid=7: reacting to signal 3
解决方案
Your NullPointer Exception is in getCount() line 27:
Caused by: java.lang.NullPointerException
at com.droidnova.android.howto.optionmenu.LazyAdapter.getCount(LazyAdapter.java:27)
You could fix the sympton by changing getCount() to:
public int getCount() {
if(data != null){
return data.length;
}
return 0;
}