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我目前有這個問題。正因爲如此，我不能做任何其他的，因爲我不得不參考這個頁面。如果有人能指出我犯的錯誤，我將不勝感激。成功在logcat但空屏幕
我想查看某個特定產品的詳細信息，其中上一頁（列表）中的按鈕將ID參數傳遞給頁面（詳細信息）。 Java代碼或PHP代碼中沒有錯誤。我很確定這是因爲Logcat顯示相應的結果（因爲我在所有地方都添加了日誌）。但該頁面在模擬器中是空的。我不明白爲什麼會發生這種情況，因爲佈局與其他頁面一樣。如果你需要的代碼，其如下：
Java代碼： list.java
ListView lv = getListView();
lv.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
String pid = ((TextView) view.findViewById(R.id.pid)).getText()
.toString();
// Starting new intent
Intent in = new Intent(getApplicationContext(),
details.class);
// sending pid to next activity
in.putExtra(TAG_PID, pid);
// starting new activity and expecting some response back
startActivity(in);
}
});
Java代碼：details.java
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_book_details);
Intent i = getIntent();
// getting product id (pid) from intent
pid = i.getStringExtra(TAG_PID);
Log.d("pid is:",pid);
new GetProductDetails().execute();
}
class GetProductDetails extends AsyncTask<String, String, String> {
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(Details.this);
pDialog.setMessage("Loading. Please wait...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
}
protected String doInBackground(String... params) {
runOnUiThread(new Runnable() {
public void run() {
int success;
try {
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("pid", pid));
JSONObject json = jParser.makeHttpRequest(url_product_details, "GET", params);
Log.d("Single Product Details", json.toString());
success = json.getInt(TAG_SUCCESS);
if (success == 1) {
JSONArray productObj = json.getJSONArray(TAG_BOOK);
int i = productObj.length(); //line 1
JSONObject product = productObj.getJSONObject(i);
String title = "Title : "+ product.getString(TAG_TITLE);
String description = product.getString(TAG_DESCRIPTION);
HashMap<String, String> map = new HashMap<String, String>();
map.put(TAG_TITLE, title);
map.put(TAG_DESCRIPTION, description);
eventsList.add(map);
Log.d("Title", title);
Log.d("Description", description);
}
}
protected void onPostExecute(String file_url) {
pDialog.dismiss();
runOnUiThread(new Runnable() {
public void run() {
ListAdapter adapter = new SimpleAdapter(
Details.this, eventsList,
R.layout.list_item2, new String[] { TAG_PID, TAG_TITLE, TAG_DESCRIPTION},
new int[] { R.id.pid, R.id.title, R.id.description });
setListAdapter(adapter);
}
});
}
}
佈局：details.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<ListView
android:layout_marginTop="70dp"
android:id="@android:id/list"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_marginLeft="20dp"/>
</LinearLayout>
logcat：
04-15 00:05:28.005: D/All Products:(4345): {"success":1,"books":[{"author":"Agnesh","category":"Fiction","title":"The Immortals of Shiva","pid":"1","price":"150","description":"Life of Shiva","discount":"20%"},{"author":"Chetan Bhagat","category":"Drama","title":"3 Mistakes of My Life","pid":"14","price":"180","description":"Story of a 3 friends and their destiny","discount":"30%"},{"author":"Chetan Bhagat","category":"Comedy","title":"Two States","pid":"15","price":"175","description":"Love Story","discount":"5%"},{"author":"Charles Darwin","category":"Personality Developm","title":"How to win friends","pid":"16","price":"250","description":"Building your confidence","discount":"10%"},{"author":"Paulo Coelho","category":"Science Fiction","title":"Alchemist","pid":"17","price":"300","description":"In search of Gold","discount":"20%"},{"author":"Vivekananda","category":"Social Awareness","title":"Call to the Nation","pid":"18","price":"100","description":"Knowing yourself","discount":"5%"}]}
04-15 00:05:29.675: D/pid is:(4345): 18
04-15 00:05:30.995: D/Single Product Details(4345): {"book":[{"author":"Vivekananda","category":"Social Awareness","title":"Call to the Nation","pid":"18","price":"100","description":"Knowing yourself","discount":"5%"}],"success":1}
04-15 00:05:31.000: W/System.err(4345): org.json.JSONException: Index 1 out of range [0..1)
04-15 00:05:31.005: W/System.err(4345): at org.json.JSONArray.get(JSONArray.java:263)
04-15 00:05:31.005: W/System.err(4345): at org.json.JSONArray.getJSONObject(JSONArray.java:480)
04-15 00:05:31.005: W/System.err(4345): at com.spyraa.store.Details$GetProductDetails$1.run(Details.java:104)
04-15 00:05:31.005: W/System.err(4345): at android.os.Handler.handleCallback(Handler.java:587)
04-15 00:05:31.005: W/System.err(4345): at android.os.Handler.dispatchMessage(Handler.java:92)
04-15 00:05:31.005: W/System.err(4345): at android.os.Looper.loop(Looper.java:130)
04-15 00:05:31.010: W/System.err(4345): at android.app.ActivityThread.main(ActivityThread.java:3691)
04-15 00:05:31.010: W/System.err(4345): at java.lang.reflect.Method.invokeNative(Native Method)
04-15 00:05:31.010: W/System.err(4345): at java.lang.reflect.Method.invoke(Method.java:507)
04-15 00:05:31.010: W/System.err(4345): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:907)
04-15 00:05:31.010: W/System.err(4345): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:665)
04-15 00:05:31.015: W/System.err(4345): at dalvik.system.NativeStart.main(Native Method)
04-15 00:05:31.020: D/AndroidRuntime(4345): Shutting down VM
04-15 00:05:31.020: W/dalvikvm(4345): threadid=1: thread exiting with uncaught exception (group=0x4001e578)
04-15 00:05:31.030: E/AndroidRuntime(4345): FATAL EXCEPTION: main
04-15 00:05:31.030: E/AndroidRuntime(4345): java.lang.NullPointerException
04-15 00:05:31.030: E/AndroidRuntime(4345): at android.widget.SimpleAdapter.getCount(SimpleAdapter.java:93)
04-15 00:05:31.030: E/AndroidRuntime(4345): at android.widget.ListView.setAdapter(ListView.java:485)
04-15 00:05:31.030: E/AndroidRuntime(4345): at android.app.ListActivity.setListAdapter(ListActivity.java:265)
04-15 00:05:31.030: E/AndroidRuntime(4345): at com.spyraa.store.Details$GetProductDetails$2.run(Details.java:166)
04-15 00:05:31.030: E/AndroidRuntime(4345): at android.app.Activity.runOnUiThread(Activity.java:3743)
04-15 00:05:31.030: E/AndroidRuntime(4345): at com.spyraa.store.Details$GetProductDetails.onPostExecute(Details.java:156)
04-15 00:05:31.030: E/AndroidRuntime(4345): at com.spyraa.store.Details$GetProductDetails.onPostExecute(Details.java:1)
04-15 00:05:31.030: E/AndroidRuntime(4345): at android.os.AsyncTask.finish(AsyncTask.java:417)
04-15 00:05:31.030: E/AndroidRuntime(4345): at android.os.AsyncTask.access$300(AsyncTask.java:127)
04-15 00:05:31.030: E/AndroidRuntime(4345): at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:429)
04-15 00:05:31.030: E/AndroidRuntime(4345): at android.os.Handler.dispatchMessage(Handler.java:99)
04-15 00:05:31.030: E/AndroidRuntime(4345): at android.os.Looper.loop(Looper.java:130)
04-15 00:05:31.030: E/AndroidRuntime(4345): at android.app.ActivityThread.main(ActivityThread.java:3691)
04-15 00:05:31.030: E/AndroidRuntime(4345): at java.lang.reflect.Method.invokeNative(Native Method)
04-15 00:05:31.030: E/AndroidRuntime(4345): at java.lang.reflect.Method.invoke(Method.java:507)
04-15 00:05:31.030: E/AndroidRuntime(4345): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:907)
04-15 00:05:31.030: E/AndroidRuntime(4345): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:665)
04-15 00:05:31.030: E/AndroidRuntime(4345): at dalvik.system.NativeStart.main(Native Method)
新的logcat：
04-15 01:37:50.695: D/pid is:(8773): 18
04-15 01:37:52.285: D/Single Product Details(8773): {"book":[{"author":"Vivekananda","category":"Social Awareness","title":"Call to the Nation","pid":"18","price":"100","description":"Knowing yourself","discount":"5%"}],"success":1}
04-15 01:37:52.295: D/AndroidRuntime(8773): Shutting down VM
04-15 01:37:52.295: W/dalvikvm(8773): threadid=1: thread exiting with uncaught exception (group=0x4001e578)
04-15 01:37:52.305: E/AndroidRuntime(8773): FATAL EXCEPTION: main
04-15 01:37:52.305: E/AndroidRuntime(8773): java.lang.NullPointerException
04-15 01:37:52.305: E/AndroidRuntime(8773): at com.spyraa.bookstore.BookDetails$GetProductDetails$1.run(BookDetails.java:127)
04-15 01:37:52.305: E/AndroidRuntime(8773): at android.os.Handler.handleCallback(Handler.java:587)
04-15 01:37:52.305: E/AndroidRuntime(8773): at android.os.Handler.dispatchMessage(Handler.java:92)
04-15 01:37:52.305: E/AndroidRuntime(8773): at android.os.Looper.loop(Looper.java:130)
04-15 01:37:52.305: E/AndroidRuntime(8773): at android.app.ActivityThread.main(ActivityThread.java:3691)
04-15 01:37:52.305: E/AndroidRuntime(8773): at java.lang.reflect.Method.invokeNative(Native Method)
04-15 01:37:52.305: E/AndroidRuntime(8773): at java.lang.reflect.Method.invoke(Method.java:507)
04-15 01:37:52.305: E/AndroidRuntime(8773): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:907)
04-15 01:37:52.305: E/AndroidRuntime(8773): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:665)
04-15 01:37:52.305: E/AndroidRuntime(8773): at dalvik.system.NativeStart.main(Native Method)
04-15 01:38:00.015: I/Process(8773): Sending signal. PID: 8773 SIG: 9
太感謝你了！
莫非你一個很好的教程發佈LogCat的輸出？ – thomas88wp
@ thomas88wp，yup，已更新。 –
您使用的是列表適配器嗎？ –