Android 为什么切换活动时我的listview为空?
我创建了两个不同的活动来显示具有不同结果的JSON数组,并将其显示到listview中。 首先,我创建菜单活动,用按钮Button1和Button2控制切换活动。 然后,我创建了两个activitiy类Activity1和Activity2,以在listview中显示我的JSON数组。 当我单击按钮1时,它工作并在listview中的Activity1上显示我的JSON数组。 但当我点击按钮2时,它什么也不显示。为什么活动2的列表视图项目丢失 这是我的listview占位符listview占位符: 这是我的菜单活动菜单活动: 这是我在listview WeeklyFlashActivity上显示JSON数组的活动所有活动基本上彼此相似不同的只是获取JSON的URL:Android 为什么切换活动时我的listview为空?,android,android-listview,android-activity,Android,Android Listview,Android Activity,我创建了两个不同的活动来显示具有不同结果的JSON数组,并将其显示到listview中。 首先,我创建菜单活动,用按钮Button1和Button2控制切换活动。 然后,我创建了两个activitiy类Activity1和Activity2,以在listview中显示我的JSON数组。 当我单击按钮1时,它工作并在listview中的Activity1上显示我的JSON数组。 但当我点击按钮2时,它什么也不显示。为什么活动2的列表视图项目丢失 这是我的listview占位符listview占位符
public class WeeklyFlashActivity extends ListActivity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.listplaceholder);
ArrayList<HashMap<String, String>> mylist = new ArrayList<HashMap<String, String>>();
JSONObject json = JSONfunctions.getJSONfromURL("http://www.greenfields.co.id:502/Service1.svc/json/weeklyflash/id");
try
{
JSONArray weeklyflash = json.getJSONArray("GetReportResult");
for(int i=0;i<weeklyflash.length();i++)
{
HashMap<String, String> map = new HashMap<String, String>();
JSONObject e = weeklyflash.getJSONObject(i);
//map.put("type", String.valueOf(i));
map.put("type", e.getString("type"));
map.put("total", e.getString("total"));
mylist.add(map);
}
}
catch(JSONException e)
{
Log.e("log_tag", "Error parsing data "+e.toString());
}
ListAdapter adapter = new SimpleAdapter(this, mylist , R.layout.wfid,
new String[] { "type", "total" },
new int[] { R.id.item_title, R.id.item_subtitle });
setListAdapter(adapter);
Button btnClose = (Button) findViewById(R.id.buttonClose);
btnClose.setOnClickListener(new View.OnClickListener() {
public void onClick(View arg0) {
//Closing SecondScreen Activity
finish();
}
});
}
}
可能是json出现在不同的url上,可能彼此不同…@Dhereshsingh我检查了所有url,它正确地显示了json格式,不同的只是total的值所有json键都相同?比如说结果?类型?总数?所有的键都是一样的?嗨,试试这个静态数组列表。@Dhereshsingh是的,所有的键都是一样的。。
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:padding="7dp"
>
<TextView
android:id="@+id/item_title"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceMedium"
android:padding="2dp"
android:textSize="20dp" />
<TextView
android:id="@+id/item_subtitle"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:padding="2dp"
android:textSize="13dp" />
</LinearLayout>
public class MenuActivity extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// TODO Auto-generated method stub
Button btnIndonesia = (Button) findViewById(R.id.button1);
Button btnMalaysia = (Button) findViewById(R.id.button2);
Button btnSingapore = (Button) findViewById(R.id.button3);
Button btnHongkong = (Button) findViewById(R.id.button4);
//Listening to button event
btnIndonesia.setOnClickListener(new View.OnClickListener() {
public void onClick(View arg0) {
//Starting a new Intent
Intent indonesiaScreen = new Intent(getApplicationContext(), WeeklyFlashActivity.class);
startActivity(indonesiaScreen);
}
});
btnMalaysia.setOnClickListener(new View.OnClickListener() {
public void onClick(View arg0) {
//Starting a new Intent
Intent malaysiaScreen = new Intent(getApplicationContext(), WeeklyFlashMyActivity.class);
startActivity(malaysiaScreen);
}
});
btnSingapore.setOnClickListener(new View.OnClickListener() {
public void onClick(View arg0) {
//Starting a new Intent
Intent singaporeScreen = new Intent(getApplicationContext(), WeeklyFlashSgActivity.class);
startActivity(singaporeScreen);
}
});
btnHongkong.setOnClickListener(new View.OnClickListener() {
public void onClick(View arg0) {
//Starting a new Intent
Intent hongkongScreen = new Intent(getApplicationContext(), WeeklyFlashHkActivity.class);
startActivity(hongkongScreen);
}
});
}
}
public class WeeklyFlashActivity extends ListActivity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.listplaceholder);
ArrayList<HashMap<String, String>> mylist = new ArrayList<HashMap<String, String>>();
JSONObject json = JSONfunctions.getJSONfromURL("http://www.greenfields.co.id:502/Service1.svc/json/weeklyflash/id");
try
{
JSONArray weeklyflash = json.getJSONArray("GetReportResult");
for(int i=0;i<weeklyflash.length();i++)
{
HashMap<String, String> map = new HashMap<String, String>();
JSONObject e = weeklyflash.getJSONObject(i);
//map.put("type", String.valueOf(i));
map.put("type", e.getString("type"));
map.put("total", e.getString("total"));
mylist.add(map);
}
}
catch(JSONException e)
{
Log.e("log_tag", "Error parsing data "+e.toString());
}
ListAdapter adapter = new SimpleAdapter(this, mylist , R.layout.wfid,
new String[] { "type", "total" },
new int[] { R.id.item_title, R.id.item_subtitle });
setListAdapter(adapter);
Button btnClose = (Button) findViewById(R.id.buttonClose);
btnClose.setOnClickListener(new View.OnClickListener() {
public void onClick(View arg0) {
//Closing SecondScreen Activity
finish();
}
});
}
}