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我一直堅持這個很長一段時間，這真的令人沮喪。基本上，應用程序以ListView開頭，其中包含Movie Titles，它們的Gross和Year。Android - 更新列表視圖
然後，用戶可以使用與菜單中的不同活動添加新電影，總值和年份。這些值然後返回到第一個活動並放置在列表的底部。
這是我的問題開始的地方。我遇到的第一個問題是應用程序Force在即將顯示新項目時關閉。現在，它根本不想顯示。下面的代碼：
public class Lab7_084106 extends ListActivity {
private SampleCustomAdapter adapter;
private ArrayList<MyMovies> movieList;
public static boolean Flag = false;
@SuppressWarnings("null")
@Override
public void onCreate(Bundle savedInstanceState) {
//create stuff
super.onCreate(savedInstanceState);
movieList = new ArrayList<MyMovies>();
Intent data = getIntent();
//Flag = data.getStringExtra("Flag");
String[] oldMovieList = getResources().getStringArray(R.array.movieArray);
String[] oldGrossList = getResources().getStringArray(R.array.worldwideGross);
String[] oldYearList = getResources().getStringArray(R.array.yearArray);
//if there's no new movie to display
if(!Flag){
for (int i = 0; i < oldMovieList.length; i++) {
MyMovies newMovie = new MyMovies();
newMovie.setMovie(oldMovieList[i] + "NEW");
newMovie.setGross(oldGrossList[i]);
newMovie.setYear(oldYearList[i]);
movieList.add(newMovie);
}
//adapter = new SampleCustomAdapter(movieList);
//setContentView(R.layout.row);
//setListAdapter(adapter);
}
else{
Toast.makeText(getApplicationContext(), "Else Entered", Toast.LENGTH_SHORT).show();
int newLength = 50; //oldMovieList.length + 1;
//create new array to store the new value
String[] newMovieArray = new String[newLength];
String[] newGrossArray = new String[newLength];
String[] newYearArray = new String[newLength];
//populate the new list with the old one plus the new one
for (int i = 0; i < newLength; i++) {
if(i != newLength - 1){
newMovieArray[i] = oldMovieList[i];
newGrossArray[i] = oldGrossList[i];
newYearArray[i] = oldYearList[i];
}
else{
newMovieArray[i] = data.getStringExtra("Title");
newGrossArray[i] = data.getStringExtra("Gross");
newYearArray[i] = data.getStringExtra("Year");
}
}
//populate the old one using the new list
for (int i = 0; i < newLength; i++) {
oldMovieList[i] = newMovieArray[i];
oldGrossList[i] = newGrossArray[i];
oldYearList[i] = newYearArray[i];
}
//display stuff
for (int i = 0; i < newLength; i++) {
MyMovies newMovie = new MyMovies();
newMovie.setMovie(oldMovieList[i]);
newMovie.setGross(oldGrossList[i]);
newMovie.setYear(oldYearList[i]);
movieList.add(newMovie);
}
//adapter = new SampleCustomAdapter(movieList);
//setListAdapter(adapter);
}
adapter = new SampleCustomAdapter(movieList);
setListAdapter(adapter);
ListView lv = getListView();
lv.setTextFilterEnabled(true);
//set stuff such that Page2 sends back a result to page 1
lv.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
TextView t = (TextView) view.findViewById(R.id.title);
String name = (String) t.getText();
Toast.makeText(getApplicationContext(), name, Toast.LENGTH_SHORT).show();
}
});
}
private class SampleCustomAdapter extends BaseAdapter {
private ArrayList<MyMovies> internalList;
String[] oldMovieList = getResources().getStringArray(R.array.movieArray);
String[] oldGrossList = getResources().getStringArray(R.array.worldwideGross);
String[] oldYearList = getResources().getStringArray(R.array.yearArray);
private ArrayList<MyMovies> GetSearchResults(){
ArrayList<MyMovies> results = new ArrayList<MyMovies>();
// make sure the arrays have the same length
for (int i = 0; i < oldMovieList.length; i++) {
MyMovies sr = new MyMovies();
sr.setMovie(oldMovieList[i]);
sr.setGross(oldGrossList[i]);
sr.setYear(oldYearList[i]);
results.add(sr);
}
return results;
}
public SampleCustomAdapter(ArrayList<MyMovies> contacts){
internalList = contacts;
}
@Override
public int getCount() {
// TODO Auto-generated method stub
return internalList.size();
}
@Override
public Object getItem(int index) {
// TODO Auto-generated method stub
return internalList.get(index);
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// NOTE: you can only do this if you have access to the Activity object
// which is why this is an inner class
LayoutInflater inflater = getLayoutInflater();
View view;
//System.out.println(parent.getClass().getName());
//System.out.println(position);
if (convertView==null){
view = inflater.inflate(R.layout.row, null);
}
else{
view = convertView;
}
// extract the views to be populated
TextView movie = (TextView) view.findViewById(R.id.title);
TextView gross = (TextView) view.findViewById(R.id.gross);
TextView date = (TextView) view.findViewById(R.id.date);
// extract the object that will fill these
MyMovies movies = GetSearchResults().get(position);
//MyMovies movies = internalList.get(position);
movie.setText(movies.getMovie());
gross.setText(movies.getGross());
date.setText(movies.getYear());
// return the view
return view;
}
}
//menu lawl
@Override
public boolean onCreateOptionsMenu(Menu menu){
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menupage1, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
//Handle item selection using item.getItemId()
switch(item.getItemId()){
case R.id.addMovie:
AddMovie();
break;
}
return true;
}
//end menu stuff lol
public void AddMovie(){
Intent intent2 = new Intent(this, com.Android.Lab7.addMovie.class);
startActivity(intent2);
finish();
}
}
如果用戶增加了電影的標誌Boolean變量主要是告訴。如果用戶添加了電影，它將進入else語句並從那裏更新。我真的很困惑在哪裏把這個if-else聲明。
我跑GetSearchResult函數SampleCustomAdapter的一些實驗，發現它直接影響ListView的輸出。我試着把if-else陳述放在那裏，但是我最終在ListView中得到了很多物品。
使用adapter.notifyDataSetChanged();會給出NullPointerException錯誤並指向我放置它的位置。所以即使這樣做：
MyMovies newMovie = new MyMovies();
newMovie.setMovie(data.getStringExtra("Title"));
newMovie.setGross(data.getStringExtra("Gross"));
newMovie.setYear(data.getStringExtra("Year"));
movieList.add(newMovie);
adapter.notifyDataSetChanged();
作爲else塊，它不起作用。我認爲這與我從string.xml資源文件夾獲取初始值而不是通過硬編碼或用戶輸入有關。
這個問題一直讓我感到沮喪，因爲2-3天前，幫助真的很感激。謝謝。
我曾嘗試過。但是，我會得到一個空指針或索引超出界限的錯誤。 – Razgriz 2012-08-21 13:35:09
檢查已更新的答案 – 2012-08-21 13:47:47
我明白了。我也更新了這個問題，我想我應該把它添加到我放置的第二塊代碼中？會發生什麼是隻顯示一部電影。 – Razgriz 2012-08-21 14:03:46