Android：应用程序关闭后将值保留在列表中

我目前正在尝试开发一个用作购物清单的应用程序，用户在其中输入文本EditText，按Button，然后将该值保存到List，然后更新ListView以其价值。该应用程序运行良好，除非用户退出应用程序，在这种情况下，用户输入的所有值都不会保存。这是我迄今为止尝试存储的List.

public class MainActivity extends ListActivity {

    private static final String SHARED_PREFS_NAME = "MY_SHARED_PREF";

    ArrayList<String> mylist = new ArrayList<String>();
    ArrayAdapter<String> adapter;

    @Override
    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        ListView listview = (ListView) findViewById(android.R.id.list);

        Button btn = (Button) findViewById(R.id.button);

        mylist = (ArrayList<String>) getArray();

        adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, mylist);

        OnClickListener listener = new OnClickListener() {          
            @Override
            public void onClick(View v) {                               
                EditText edit = (EditText) findViewById(R.id.edittext);
                mylist.add(edit.getText().toString());
                edit.setText("");               
                adapter.notifyDataSetChanged();
            }
        };

        btn.setOnClickListener(listener);

        listview.setAdapter(adapter);   

    }

    public boolean saveArray() {

        SharedPreferences sp = this.getSharedPreferences(SHARED_PREFS_NAME, Activity.MODE_PRIVATE);
        SharedPreferences.Editor mEdit1 = sp.edit();
        Set<String> set = new HashSet<String>();
        set.addAll(mylist);        
        mEdit1.putStringSet("list", set);

        return mEdit1.commit();     

    }

    public List<String> getArray() {

        SharedPreferences sp = this.getSharedPreferences(SHARED_PREFS_NAME, Activity.MODE_PRIVATE);
        Set<String> set = sp.getStringSet("list", new HashSet<String>());
        return new ArrayList<String>(set);
    }

}

并在我的.xml我有布局文件

<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" >

    <EditText
        android:id="@+id/edittext"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:ems="10" >

        <requestFocus />
    </EditText>

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_below="@+id/edittext"
        android:text="Button" />

    <ListView
        android:id="@android:id/list"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_below="@+id/button" >
    </ListView>

</RelativeLayout>

我有它，以便可以将值输入到ListView正确，但是ListView应用程序退出并重新打开后不会保存其值。有谁知道为什么会发生这种情况？

您的问题的解决方案如下：

我尝试并修改了你的代码也感谢这个link https://stackoverflow.com/questions/7057845/save-arraylist-to-sharedpreferences:

public class MainActivity extends ListActivity {

    private static final String SHARED_PREFS_NAME = "MY_SHARED_PREF";
    ArrayList<String> mylist = new ArrayList<String>();
    ArrayAdapter<String> adapter;

    @Override
    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        ListView listview = (ListView) findViewById(R.id.list);
        Button btn = (Button) findViewById(R.id.button);

        //NOTE: acquire array from shared preferences
        mylist = getArray();

        adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, mylist);

        OnClickListener listener = new OnClickListener() {          
            @Override
            public void onClick(View v) {                               
                EditText edit = (EditText) findViewById(R.id.edittext);
                mylist.add(edit.getText().toString());
                edit.setText("");               
                adapter.notifyDataSetChanged();
            }
        };
        btn.setOnClickListener(listener);
        listview.setAdapter(adapter);        
    }

    public boolean saveArray() {
        SharedPreferences sp = this.getSharedPreferences(SHARED_PREFS_NAME, Activity.MODE_PRIVATE);
        SharedPreferences.Editor mEdit1 = sp.edit();
        Set<String> set = new HashSet<String>();
        set.addAll(mylist);
        mEdit1.putStringSet("list", set);
        return mEdit1.commit();
    }

    public ArrayList<String> getArray() {
        SharedPreferences sp = this.getSharedPreferences(SHARED_PREFS_NAME, Activity.MODE_PRIVATE);

        //NOTE: if shared preference is null, the method return empty Hashset and not null          
        Set<String> set = sp.getStringSet("list", new HashSet<String>());

        return new ArrayList<String>(set);
    }
}

..并在关闭应用程序之前调用 SaveArray ()

public void onStop() {
    saveArray();
    super.onStop();
}

或者，每次添加元素时保存数组（all'onclick 按钮会覆盖当前列表中的共享首选项）