所以我正在尝试为ListView排序一个简单的ArrayAdapter.这是我尝试过的:
ListView lv;
String[] months = {
"January",
"February",
"march",
"April",
"May",
"June",
"July",
"August",
"September",
"October",
"November",
"December"
};
ArrayAdapter<String> adapter;
ArrayList<String> list;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
lv = (ListView) findViewById(R.id.listView1);
lv.setFastScrollEnabled(true);
adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, months);
lv.setAdapter(adapter);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onoptionsItemSelected(MenuItem item) {
// Todo Auto-generated method stub
switch (item.getItemId()) {
case R.id.sortasc:
list = new ArrayList<String>(Arrays.asList(months));
Collections.sort(list);
for (int i = 0; i < list.size(); i++) {
System.out.println(list.get(i));
}
adapter.clear();
adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, list);
adapter.notifyDataSetChanged();
return true;
case R.id.sortdesc:
return true;
default:
return super.onoptionsItemSelected(item);
}
}
但我得到UnsupportedOperationException,这有什么问题?我真的需要帮助.提前致谢!
解决方法:
在对项目进行排序后,您没有调用setAdapter(适配器).
使用如下
adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, list);
lv.setAdapter(adapter);
adapter.notifyDataSetChanged();
代替
adapter.clear(); // Useless
adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, list);
adapter.notifyDataSetChanged();
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