我知道网上有关于notifyDataSetChanged()的信息；以及如何使用它，但我似乎无法弄清楚如何在我的具体情况下使用它。我不知道是否应该在我的活动、适配器类或什么中调用它。我只是希望 listView 在行滚动离开屏幕时不要更改用户之前输入的文本以返回到默认文本。
MainActivity.java
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.app.Activity;
import android.view.KeyEvent;
import android.view.View;
import android.view.inputmethod.EditorInfo;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.ViewSwitcher;
import java.util.ArrayList;
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final ArrayList<String> Chores = new ArrayList<>();
Chores.add("");
final ListAdapter MyAdapter = new CustomAdapter(this, Chores);
ListView listViewObject = (ListView)findViewById(R.id.customListView_ID);
listViewObject.setAdapter(MyAdapter);
listViewObject.setOnItemClickListener(
new AdapterView.OnItemClickListener(){
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id){
String ChoreString = String.valueOf(parent.getItemAtPosition(position));
}
}
);
final Button button = (Button) findViewById(R.id.button_ID);
button.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
Chores.add("");
((ArrayAdapter)MyAdapter).notifyDataSetChanged();
}
});
}
}
自定义适配器.java
import android.content.Context;
import android.content.DialogInterface;
import android.support.annotation.NonNull;
import android.support.v7.app.AlertDialog;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.ImageView;
import android.widget.TextView;
import java.util.ArrayList;
import static com.example.emilythacker.chorelist.R.id.textView_ID;
class CustomAdapter extends ArrayAdapter{
public CustomAdapter(Context context, ArrayList choreText) {
super(context, R.layout.custon_listview_row, choreText);
}
@NonNull
@Override
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater myInflater = LayoutInflater.from(getContext());
View customView = myInflater.inflate(R.layout.custon_listview_row, parent, false);
ImageButton imageButton = (ImageButton) customView.findViewById(R.id.imageButton_ID);
final TextView textView = (TextView) customView.findViewById(textView_ID);
textView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//what happens when textView is clicked
AlertDialog alertDialog = new AlertDialog.Builder(getContext()).create();
final EditText input = new EditText(getContext());
input.setHint("hint");
alertDialog.setView(input);
alertDialog.setTitle("Set Chore");
alertDialog.setMessage("Alert message to be shown");
alertDialog.setButton(AlertDialog.BUTTON_NEUTRAL, "OK", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
//this will set text to "hello" only if user does not enter anything into input
//textView.setText("hello");
//this also will only work if there is no input entered into input...which will change textView into empty space
textView.setText(input.getText().toString());
//works the same with or without dialog.dismiss();
dialog.dismiss();
}
});
alertDialog.show();
}
});
imageButton.setImageResource(R.drawable.clock);
return customView;
}
}
该问题不是由notifyDataSetChanged()引起的；但是因为您没有在适配器中重用视图，也没有设置要在 getView() 中设置的数据
最好尝试使用viewholder模式或使用recyclerview。
class CustomAdapter extends ArrayAdapter{
ArrayList<String> choreText;
public CustomAdapter(Context context, ArrayList choreText) {
super(context, R.layout.custon_listview_row, choreText);
this.choreText = choreText;
}
@NonNull
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder;
if (convertView == null) {
LayoutInflater layoutInflater = LayoutInflater.from(getContext());
convertView = layoutInflater.inflate(R.layout.custon_listview_row, parent, false);
holder = new ViewHolder();
holder.imageButton = (ImageButton) customView.findViewById(R.id.imageButton_ID);
holder.textView = (TextView) customView.findViewById(textView_ID);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
holder.textView.setText(choreText.get(position));
holder.textView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//what happens when textView is clicked
AlertDialog alertDialog = new AlertDialog.Builder(getContext()).create();
final EditText input = new EditText(getContext());
input.setHint("hint");
alertDialog.setView(input);
alertDialog.setTitle("Set Chore");
alertDialog.setMessage("Alert message to be shown");
alertDialog.setButton(AlertDialog.BUTTON_NEUTRAL, "OK", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
//this will set text to "hello" only if user does not enter anything into input
//textView.setText("hello");
//this also will only work if there is no input entered into input...wich will change textView into empty space
textView.setText(input.getText().toString());
//works the same with or without dialog.dismiss();
dialog.dismiss();
}
});
alertDialog.show();
}
});
holder.imageButton.setImageResource(R.drawable.clock);
return customView;
}
static class ViewHolder {
ImageButton imageButton;
TextView textView;
}
}
Chores.add("");2.滚动时，它将重新创建视图，更好地选择使用视图持有者。
3.要保留视图数据，请创建一个数组来存储编辑文本的文本数据。
// initialise the array inside constructor
stringArray = new String[choreText.size()] ;
4.每次确定后，单击将数据保存到数组中并调用notifyDataSetChanged
alertDialog.setButton(AlertDialog.BUTTON_NE UTRAL, "OK", new DialogInterface.OnClickListener()
{ public void onClick(DialogInterface dialog, int which) {
//this will set text to "hello" only if user does not enter anything into input
textView.setText("hello");
//this also will only work if there is no input entered into input...which will change textView into empty space
textView.setText(input.getText().toString());
stringArray[position]=input.getText().toString();
notifyDataSetChanged();
//works the same with or without
dialog.dismiss(); dialog.dismiss(); } });
4.设置数组中保留的文本，在你的getview中添加这一行
textview.setText(stringArray[position]==null?"":stringArray[position];