我有 2 种不同的活动,我可以在它们之间更改。但是当我转到第二个活动并按回时,列表视图没有显示。我似乎找不到问题所在。
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
currentLayout = R.layout.activity_main;
db = new TodoDbHelper(this);
todos = db.getAllTodos();
nrOfTodos = todos.size();
//For ListView
mListView = (ListView) findViewById(R.id.gradientBackground);
mAdapter = new TodoAdapter<String>(this, R.layout.text_view_item_default);
mListView.setAdapter(mAdapter);
//Calculate height of screen
Display display = getWindowManager().getDefaultDisplay();
Point size = new Point();
display.getSize(size);
int width = size.x;
int height = size.y;
listItemSize = height/10;
SCREEN_WIDTH = width;
createTodoItems();
}
public void createTodoItems() {
refresh();
mAdapter.clear();
for(int i = 0; i < nrOfTodos; i++) {
String title = todos.get(i).getTitle();
mAdapter.add(title);
//System.out.println(title);
//System.out.println(mAdapter);
}
mListView.setAdapter(mAdapter);
ImageButton b = (ImageButton) findViewById(R.id.addButton);
b.bringToFront();
}
public void refresh() {
todos = db.getAllTodos();
nrOfTodos = todos.size();
}
@Override
public void onBackPressed() {
System.out.println("" + this.findViewById(android.R.id.content).getRootView());
System.out.println("" + currentLayout);
if(R.layout.activity_add_todo == currentLayout) {
setContentView(R.layout.activity_main);
currentLayout = R.layout.activity_main;
createTodoItems();
Log.d("onBackPressed", "We're going back.");
}
}
我两次都做同样的"createTodoItems()",但第二次似乎无关紧要。
此外,在第二个创建TodoItems()之后,mAdapter似乎是一样的。mAdapter 中的值仍然相同。
添加新项目时出现相同问题。它只是不会从列表视图中呈现任何内容。
尝试添加此函数 notifyDataSetChanged(),可能会有所帮助:
public void createTodoItems() {
refresh();
mAdapter.clear();
for(int i = 0; i < nrOfTodos; i++) {
title = todos.get(i).getTitle();
mAdapter.add(title);
//System.out.println(title);
//System.out.println(mAdapter);
}
mListView.setAdapter(mAdapter);
mAdapter.notifyDataSetChanged();
ImageButton b = (ImageButton) findViewById(R.id.addButton);
b.bringToFront();
}