使用Sharedpreferences填充Listview

Question

在我的应用程序中，我有一个listview，其中包含一个字符串“Add New String”。当用户选择此项时，“警报”对话框会提示一个编辑文本和按钮。用户必须在此框中写入新String的名称，并且当用户单击必须添加到原始列表的按钮时。直到我已经完成了。但我的问题是当用户关闭此应用程序并重新启动时，然后列表中没有新添加的字符串。我必须以共享的偏好来做这件事。怎么可以用呢？这是我的代码。

MainActivity .java

public class MainActivity extends Activity {

    ListView lv;
    String add[]=new String[]{"Add new List"}; 
    final private static int DIALOG_LOGIN = 1;
    ArrayList<String> arr1;
    ArrayAdapter<String> adapter1;

    ArrayList<String> arr2 = new ArrayList<String>();
    ArrayAdapter<String> adapter2;

    int count = 0;
    int i=0;

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

        lv = (ListView)findViewById(R.id.listView1);
        adapter1 = new ArrayAdapter<String>(getBaseContext(), android.R.layout.simple_list_item_1, add);
        lv.setAdapter(adapter1);
        //onLoad();

        lv.setOnItemClickListener(new OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
                    long arg3) {
                // TODO Auto-generated method stub
                String data = lv.getItemAtPosition(arg2).toString();
                if(data == "Add new List")
                {
                     count = count + 1;
                     showDialog(DIALOG_LOGIN);
                }
            }
        });

    }


      @Override
     protected Dialog onCreateDialog(int id)
      {

      AlertDialog dialogDetails = null;

      switch (id)
      {
        case DIALOG_LOGIN:
        LayoutInflater inflater = LayoutInflater.from(this);
        View dialogview = inflater.inflate(R.layout.dialog, null);
        AlertDialog.Builder dialogbuilder = new AlertDialog.Builder(this);
        dialogbuilder.setView(dialogview);
        dialogDetails = dialogbuilder.create();
        break;
      }

      return dialogDetails;
     }

    @Override
     protected void onPrepareDialog(int id, Dialog dialog) {

      switch (id) {
      case DIALOG_LOGIN:
       final AlertDialog alertDialog = (AlertDialog) dialog;
       Button btnOk = (Button) alertDialog.findViewById(R.id.btnOk);
       final EditText etList = (EditText) alertDialog.findViewById(R.id.etList);


       btnOk.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            if(etList.length() <= 0)
            {
                etList.requestFocus();
                Toast.makeText(getBaseContext(), "Enter Name of List", 1000).show();
            }
            else
            {
                String name = etList.getText().toString();
                String newName[] = new String[]{};

                if(arr2.contains("Add new List"))
                {

                    arr2.add(name);
                    Toast.makeText(getBaseContext(), "" + name , 1000).show();
                    adapter2 = new ArrayAdapter<String>(getBaseContext(), android.R.layout.simple_list_item_1, arr2);
                    lv.setAdapter(adapter2);
                    adapter2.notifyDataSetChanged();
                    etList.setText("");
                    Toast.makeText(getBaseContext(), "" + count, 1000).show();

                    dismissDialog(DIALOG_LOGIN);
                }
                else
                {
                    arr2.add("Add new List");
                    arr2.add(name);
                    adapter2 = new ArrayAdapter<String>(getBaseContext(), android.R.layout.simple_list_item_1, arr2);
                    lv.setAdapter(adapter2);
                    adapter2.notifyDataSetChanged();
                    etList.setText("");
                    dismissDialog(DIALOG_LOGIN);
                }
                }
    }
    });

       break;
      }
     }  

    }

activity_main.xml中

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    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=".MainActivity" >

    <ListView
        android:id="@+id/listView1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true" >
    </ListView>

</RelativeLayout>

dialog.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <EditText
        android:id="@+id/etList"
        android:layout_width="wrap_content"
        android:layout_height="50dp"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginLeft="16dp"
        android:ems="10"
        android:hint="@string/etHint" >

        <requestFocus />
    </EditText>

    <Button
        android:id="@+id/btnOk"
        android:layout_width="wrap_content"
        android:layout_height="50dp"
        android:layout_alignParentTop="true"
        android:layout_toRightOf="@+id/etList"
        android:text="@string/ok" />

</RelativeLayout>

Answer 1

您可以使用btnOk的{​​{1}}方法将数据保存到共享偏好设置。您可以在onClick()方法的arr2.add(name);行之前保存数据。

使用共享偏好设置。

要获取共享偏好，

onClick()

要编辑和保存首选项，

SharedPreferences prefs = this.getSharedPreferences(
      "com.example.app", Context.MODE_PRIVATE);

要阅读偏好，

String myString = "TextHere";
prefs.edit().putString("com.example.app.myValue", myString).commit();