Android ListView 在 saveButton 之后没有更新，而是在 onItemSelected 之后更新
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【中文标题】Android ListView 在 saveButton 之后没有更新，而是在 onItemSelected 之后更新【英文标题】：Android ListView is not updating after saveButton, but after onItemSelected 【发布时间】：2016-07-12 18:12:38 【问题描述】：我目前正在开发一款适用于学校的 android 应用程序。我已经查看了论坛并尝试自己解决问题，但我似乎无法弄清楚为什么当我按下保存按钮时我的 ListView 不会自动更新。我实际上必须在更新之前按下下拉菜单并选择和项目。谁能看看它，让我知道我做错了什么？
谢谢！
activity_main.xml
<GridLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/GridLayout1"
android:layout_
android:layout_
android:columnCount="1"
android:orientation="horizontal"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.physicalactivitytracker.MainActivity" >
<Spinner
android:id="@+id/activityDropDown"
android:layout_
android:layout_
android:layout_gravity="start"
android:background="@android:drawable/btn_dropdown"
android:entries="@array/activity_array"
android:spinnerMode="dropdown" >
<requestFocus/>
</Spinner>
<LinearLayout android:layout_gravity="fill_horizontal"
android:focusable="true"
android:focusableInTouchMode="true">
<EditText
android:id="@+id/infoText"
android:layout_
android:layout_
android:layout_weight="1"
android:layout_gravity="bottom|fill_horizontal"
android:ems="10"
android:hint="@string/infoHint"
android:imeOptions="actionDone"
android:singleLine="true"
android:lines="1"
android:inputType="number" />
<ImageButton
android:id="@+id/saveButton"
android:layout_
android:layout_
android:contentDescription="@string/saveDescription"
android:src="@android:drawable/ic_menu_save" />
</LinearLayout>
<LinearLayout android:gravity="fill_horizontal" >
<Button
android:id="@+id/soFarButton"
style="android:buttonBarStyle"
android:layout_
android:layout_
android:text="@string/psf" />
<Button
android:id="@+id/startOverButton"
style="android:buttonBarStyle"
android:layout_
android:layout_
android:text="@string/so" />
</LinearLayout>
<LinearLayout
android:layout_
android:layout_gravity="fill"
android:layout_marginTop="@dimen/activity_vertical_margin"
android:background="@android:color/holo_blue_bright"
android:orientation="vertical"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin" >
<TextView
android:id="@+id/textView1"
android:layout_
android:layout_
android:layout_gravity="fill_horizontal"
android:gravity="center_horizontal"
android:text="@string/taggedSearches"
android:textAppearance="?android:attr/textAppearanceMedium" />
<ListView
android:id="@android:id/list"
android:layout_
android:layout_
android:layout_gravity="fill"
android:layout_weight="1" />
</LinearLayout>
activity_list.xml
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/textView"
android:layout_
android:layout_
android:gravity="center_vertical"
android:textAppearance="?android:attr/textAppearanceMedium" >
MainActivity.java
package com.example.physicalactivitytracker;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import android.app.AlertDialog;
import android.app.ListActivity;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.SharedPreferences;
import android.net.Uri;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.inputmethod.InputMethodManager;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.AdapterView.OnItemLongClickListener;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends ListActivity
private static final String SEARCHES = "searches";
private Spinner activityDropDown;
private ImageButton saveButton;
private EditText infoText;
private SharedPreferences savedSearches;
private ArrayList<String> tags;
private ArrayAdapter<String> adapter;
@Override
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
addItemsOnSpinner();
// get references
activityDropDown = (Spinner) findViewById(R.id.activityDropDown);
infoText = (EditText) findViewById(R.id.infoText);
activityDropDown.setOnItemSelectedListener(acList);
//Get Users Saved Searches
savedSearches = getSharedPreferences(SEARCHES, MODE_PRIVATE);
// Store Saved Info to List
tags = new ArrayList<String>(savedSearches.getAll().keySet());
// Create Array Adapter
adapter = new ArrayAdapter<String>(this, R.layout.activity_list_item, tags);
setListAdapter(adapter);
// Register Listener to Save Searches
ImageButton saveButton = (ImageButton) findViewById(R.id.saveButton);
saveButton.setOnClickListener(saveButtonListener);
// Register listener to touches on list
getListView().setOnItemClickListener(itemClickListener);
// Set Listener on long click item to edit/delete/etc
getListView().setOnItemLongClickListener(itemLongClickListener);
//end on create
//saveButtonListener for Saving Info to List
public OnClickListener saveButtonListener = new OnClickListener()
@Override
public void onClick(View v)
// create info tags that match drop down activity
if (infoText.getText().length() > 0 && infoText.getText().toString().matches(".*\\d+.*")
&& activityDropDown.getSelectedItem().toString().matches("Walking"))
addTaggedSearch(activityDropDown.getSelectedItem().toString() + " " + infoText.getText().toString()
+ " Miles");
infoText.setText(""); // clear infoText
else if (infoText.getText().length() > 0 && infoText.getText().toString().matches(".*\\d+.*")
&& activityDropDown.getSelectedItem().toString().matches("Running"))
addTaggedSearch(activityDropDown.getSelectedItem().toString() + " " + infoText.getText().toString()
+ " Miles");
infoText.setText(""); // clear infoText
else if (infoText.getText().length() > 0 && infoText.getText().toString().matches(".*\\d+.*")
&& activityDropDown.getSelectedItem().toString().matches("Stairs"))
addTaggedSearch(activityDropDown.getSelectedItem().toString() + " " + infoText.getText().toString()
+ " Number of Floors");
infoText.setText(""); // clear infoText
else if (infoText.getText().length() > 0 && infoText.getText().toString().matches(".*\\d+.*")
&& activityDropDown.getSelectedItem().toString().matches("Generic"))
addTaggedSearch(activityDropDown.getSelectedItem().toString() + " " + infoText.getText().toString()
+ " Calories");
infoText.setText(""); // clear infoText
else // display message asking user to enter info
// create new alert
AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
// set alert message to display
builder.setMessage(R.string.missingMessage);
// provide an OK button to dismiss dialog
builder.setPositiveButton(R.string.OK, null);
// create the alert dialog from builder
AlertDialog errorDialog = builder.create();
errorDialog.show(); // displays error dialog
; // end OnClickListener
// add new search to save file and refresh buttons
private void addTaggedSearch(String tag)
// get a SharedPrefrences.Editor to store info
SharedPreferences.Editor preferencesEditor = savedSearches.edit();
preferencesEditor.putString(tag, tag); // store search
preferencesEditor.apply(); // store updated preference
// add info
if (!tags.add(tag))
tags.add(tag); // add new tag
adapter.notifyDataSetChanged(); // rebind tags to ListView
// end add tag
// itemClickListenerListener opens tag info
OnItemClickListener itemClickListener = new OnItemClickListener()
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id)
//show tag info
; // end itemClickListener
//itemLongCLickListener displays a dialog allowing user to delete or edit saves list item
OnItemLongClickListener itemLongClickListener = new OnItemLongClickListener()
@Override
public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id)
// get tag that user clicked
final String tag = ((TextView) view).getText().toString();
// create new alert dialog
AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
// set the AlertDialog Title
builder.setTitle(getString(R.string.shareEditDeleteTitle, tag));
// set list of items to display in alert
builder.setItems(R.array.dialog_items, new DialogInterface.OnClickListener()
// respond to touch by sharing, editing or deleting
@Override
public void onClick(DialogInterface dialog, int which)
switch (which)
case 0: //share
shareSearch(tag);
break;
case 1: //edit
// sets infoText to match tag
infoText.setText(tag);
infoText.setText(savedSearches.getString(tag, ""));
break;
case 2: // delete
deleteSearch(tag);
break;
//end DialogInterface.OnClickListener
); // end call to builder.setItems
// set AlertDialog negative Button
builder.setNegativeButton(getString(R.string.cancel), new DialogInterface.OnClickListener()
// called when cancel button is clicked
public void onClick(DialogInterface dialog, int id)
dialog.cancel(); //dismiss AlertDialog
); // end call to setNegativeButon
builder.create().show(); //display AlertDialog
return true;
// end method onItemLongClick
; // end onItemLongClick declaration
//allow user to choose an app for sharing saved items
private void shareSearch(String tag)
// create Intent to share urlString
Intent shareIntent = new Intent();
shareIntent.setAction(Intent.ACTION_SEND);
shareIntent.putExtra(Intent.EXTRA_SUBJECT, getString(R.string.shareSubject));
shareIntent.putExtra(Intent.EXTRA_TEXT, getString(R.string.shareMessage));
shareIntent.setType("text/plain");
// display apps that can share text
startActivity(Intent.createChooser(shareIntent, getString(R.string.shareSearch)));
// deletes search after user confirms the delete operation
private void deleteSearch(final String tag)
// create new AlertDialog
AlertDialog.Builder confirmBuilder = new AlertDialog.Builder(this);
// set the AlertDialog message
confirmBuilder.setMessage(getString(R.string.confirmMessage, tag));
// set AlertDialog negative message
confirmBuilder.setNegativeButton(getString(R.string.cancel), new DialogInterface.OnClickListener()
// called when Cancel is clicked
public void onClick(DialogInterface dialog, int id)
dialog.cancel(); // dismiss dialog
); // end call to setNegativeButton
// set the AlertDialogs positive button
confirmBuilder.setPositiveButton(getString(R.string.delete), new DialogInterface.OnClickListener()
// called when Cancel button is clicked
public void onClick(DialogInterface dialog, int id)
tags.remove(tag); // remove tag from tags
// get SharePrefrences.Editor to remove saved info
SharedPreferences.Editor preferencesEditor = savedSearches.edit();
preferencesEditor.remove(tag); // remove search
preferencesEditor.apply(); // save the changes
// rebind tags ArrayList to ListView to show updates list
adapter.notifyDataSetChanged();
// end OnClickListener
); // end call to setPositiveButton
confirmBuilder.create().show(); // display AlertDialog
// end method Delete Search
public void addItemsOnSpinner()
activityDropDown = (Spinner) findViewById(R.id.activityDropDown);
List<String> list = new ArrayList<String>();
list.add("Walking");
list.add("Running");
list.add("Stairs");
list.add("Generic");
ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, list);
dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
activityDropDown.setAdapter(dataAdapter);
// on Item Select Update infoText Hint
public OnItemSelectedListener acList = new OnItemSelectedListener()
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id)
String selectedItem = parent.getItemAtPosition(position).toString();
if(selectedItem.equals("Walking"))
infoText.setHint("# of Miles Walked");
else if(selectedItem.equals("Running"))
infoText.setHint("# of Miles Ran");
else if(selectedItem.equals("Stairs"))
infoText.setHint("# of Floors Walked");
else if(selectedItem.equals("Generic"))
infoText.setHint("# of Calories Burned");
@Override
public void onNothingSelected(AdapterView<?> arg0)
// TODO Auto-generated method stub
;
public void addListenerOnSpinnerItemSelection()
activityDropDown = (Spinner) findViewById(R.id.activityDropDown);
activityDropDown.setOnItemSelectedListener(new CustomOnItemSelectedListener());
public void addListenerOnButton()
activityDropDown = (Spinner) findViewById(R.id.activityDropDown);
saveButton = (ImageButton) findViewById(R.id.saveButton);
@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)
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings)
return true;
return super.onOptionsItemSelected(item);
【问题讨论】：
【参考方案1】：我实际上找到了我的问题的答案……哈。
如果你仔细看看
public OnClickListener saveButtonListener = new OnClickListener()
@Override
public void onClick(View v)
// create info tags that match drop down activity
if (infoText.getText().length() > 0 && infoText.getText().toString().matches(".*\\d+.*")
&& activityDropDown.getSelectedItem().toString().matches("Walking"))
addTaggedSearch(activityDropDown.getSelectedItem().toString() + " " + infoText.getText().toString()
+ " Miles");
infoText.setText(""); // clear infoText
你可以看到我忘记添加了
adapter.notifyDataSetChanged();
这会阻止应用正确更新。
感谢任何试图解决这个问题的人，很抱歉浪费了任何人的时间:)
【讨论】：
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