Question

我正在尝试在弹出对话框中添加editText，以供用户编写笔记/任务，但是单击“添加”按钮后无法保存editText中的值，消息没有显示在ListView上。这是代码：

   public class MainActivity extends AppCompatActivity {

    private ListView listView;
    public static ArrayList<String> notes = new ArrayList<>();
    public static CustomAdapter arrayAdapter;
    private CheckBox checkBox;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        CheckBox checkBox = (CheckBox) findViewById(R.id.checkBox);
        ListView listView = (ListView) findViewById(R.id.listView);
        FloatingActionButton fab = (FloatingActionButton)findViewById(R.id.fab);

        SharedPreferences sharedPreferences =
                getApplicationContext().getSharedPreferences
                        ("com.example.assignment2", Context.MODE_PRIVATE);

        HashSet<String> set = (HashSet<String>)
                sharedPreferences.getStringSet("notes", null);

        if (set == null) {

            notes.add("Empty");

        } else {

            notes = new ArrayList(set);

        }

        arrayAdapter = new CustomAdapter
                (this, R.layout.simplerow, notes);

        listView.setAdapter(arrayAdapter);

        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                final EditText input = new EditText(MainActivity.this);
               AlertDialog ad = new AlertDialog.Builder(MainActivity.this)
                    .setTitle("Add Task")
                    .setMessage("Enter Message")
                    .setIcon(android.R.drawable.ic_input_add)
                    .setView(input)
                    .setPositiveButton("Add", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {

                      String task = input.getText().toString();
                      notes.add(task);
                        arrayAdapter.notifyDataSetChanged();

                        SharedPreferences sharedPreferences =
                                getApplicationContext().getSharedPreferences
                                        ("com.example.assignment2",
                                                Context.MODE_PRIVATE);

              HashSet<String> set = new HashSet(notes);

              sharedPreferences.edit().putStringSet("notes", set).commit();
                    }
                })
                        .setNegativeButton("Cancel", null)
                        .create();
                ad.show();
            }

            });

对话框看起来像this。我期望该消息将被保存并在单击“添加”按钮后显示here 有人愿意帮助吗？ :( 笔记是一个 ArrayList 。

Answer 1

在Activity的onCreate方法中移动这行颂歌。

private SharedPreferences sharedPreferences;

在onCreate

sharedPreferences = getApplicationContext()
                              .getSharedPreferences("com.example.assignment2",
                                            Context.MODE_PRIVATE);

无法在Alertdialog中更新EditText值

1 个答案: