如何在 Android Studio 中保存内部收集的数据？

Question

我正在为我的独立学习创建一个简单的笔记应用程序。问题是，每当退出应用程序时，创建的注释都会被删除，并且应用程序会完全重置。我已经阅读了几个首选项和 saveoninstance 方法的教程，但无论我尝试多少种不同的实现方式，我似乎都无法弄清楚。

public class Home extends Activity {
//Declaration of variables
private Button mNoteButton;
private String mText;
private ListView myList;
private int index;
public static final String TAG = Note.class.getSimpleName();
ArrayList<String> myArrayList= new ArrayList<String>();
ArrayAdapter<String> myAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_home);

    //Setting the list item to blank
    if (mText == null) {
        mText = "";
    }
    Log.d(TAG, mText);

    //creating adapter to insert myListArray into the ListView
    myAdapter=new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,myArrayList);
    //Setting the adapter to myArrayList
    myList= (ListView) findViewById(R.id.noteList);
    myList.setAdapter(myAdapter);
    //Creating and setting the new note button
    mNoteButton = (Button)findViewById(R.id.newNoteButton);
    //When button is clicked
    mNoteButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            newNote();
        }
    });
    //When an item in the list is clicked
    myList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            //Taking the data in the item selected and sending it to the EditNote.java
            index = position;
            //Selecting item data
            String old = myArrayList.get(index);
            Intent intent = new Intent(Home.this, EditNote.class);
            intent.putExtra("note_text", old);
            startActivityForResult(intent, 1);
        }
    });
}

private void newNote()
{
    //Starts and sends data to Note.java and creates a new note
    Intent intent = new Intent(this, Note.class);
    startActivityForResult(intent, 0);
}
protected void onActivityResult(int requestCode, int resultCode, Intent DATA) {
    super.onActivityResult(requestCode, resultCode, DATA);
    //Data from the Note activity is received
    if (requestCode == 1 && resultCode == RESULT_OK)
    {
        //Gets data and saves it to myListArray as new edit
        Bundle save = DATA.getExtras();
        String extra = save.getString("note");
        myArrayList.set(index, extra);
        myList.setAdapter(myAdapter);
    }
    if (requestCode == 0 && resultCode == RESULT_OK) {
        //Gets data and saves it to myListArray as new note
        Bundle pack = DATA.getExtras();
        String pageText = pack.getString("note");
        myArrayList.add(pageText);
        myList.setAdapter(myAdapter);
    }

这是不保存收集的字符串的代码。有人可以帮我弄清楚如何实现其中一种方法来保存此数据，以便在应用程序被销毁后可以检索它吗？

Answer 1

一种选择是将字符串作为文件写入内部存储：

http://developer.android.com/guide/topics/data/data-storage.html#filesInternal

String FILENAME = "yourFileName";
String extra = save.getString("note");
FileOutputStream fileOutputStream = openFileOutput(FILENAME, Context.MODE_PRIVATE);
fileOutputStream.write(extra.getBytes());
fileOutputStream.close();

当然，当您

打开应用程序时，您还必须读取文件，以便设置以前保存的任何注释：

1. 调用 openFileInput（） 并向其传递要读取的文件的名称。这将返回一个 FileInputStream。
2. 使用 read（） 从文件中读取字节。
3. 然后使用 close（） 关闭流。

您可能会发现此信息有助于将 fileInputStream 转换为字符串：如何在java中将FileInputStream转换为字符串？