如何從單擊的ListView項目編輯保存的數據？

Question

我有兩個活動。在CreateAccount課程中，我正在製作一個listView，其中包含用戶保存的所有帳戶。在Accounts類中，我正在保存數據，該數據類似於CreateAccount類中的listView中的新行。

我希望當一個listView項目被選中，能夠編輯保存的信息，並按下Save按鈕保存新的數據。我的問題是，當我編輯保存的信息並單擊「保存」按鈕時，它不會更改此帳戶，但會使用更改後的信息創建另一個帳戶。你能幫我解決這個問題嗎？

這裏是我的代碼

public class CreateAccount extends ListActivity { 

Intent intent; 
Button button3; 
ListView listView; 
ArrayList<String> listItems = new ArrayList<String>(); 
ArrayAdapter<String> adapter; 
SharedPreferences preferences; 

public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_create_account); 
    listView = (ListView) findViewById(android.R.id.list); 
    button3 = (Button) findViewById(R.id.button3); 

    button3.setOnClickListener(new View.OnClickListener() { 

     @Override 
     public void onClick(View v) { 
      Intent intent = new Intent(CreateAccount.this, Accounts.class); 
      startActivity(intent); 

     } 
    }); 

    listView = (ListView) findViewById(android.R.id.list); 
    SharedPreferences preferences = PreferenceManager 
      .getDefaultSharedPreferences(this); 
    int num = Accounts.num; 
    num = preferences.getInt("Account_num", num); 
    List<String> list = new LinkedList<String>(); 
    for (int i = 1; i <= num; i++) { 
     list.add(preferences.getString("account_name_" + i, "")); 
    } 
    listItems.addAll(list); 
    ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, 
      android.R.layout.simple_list_item_1, listItems); 
    listView.setAdapter(adapter); 

    OnItemClickListener listener = new OnItemClickListener() { 
     public void onItemClick(AdapterView<?> parent, View view, 
       int position, long id) { 
      Intent intent = new Intent(CreateAccount.this, Accounts.class); 
      intent.putExtra("position", position); 
      startActivity(intent); 
     } 
    }; 
    listView.setOnItemClickListener(listener); 
} 
} 


public class Accounts extends Activity { 
static EditText webSite; 
EditText userName; 
EditText pass; 
Button save; 
SharedPreferences preferences; 
Intent intent; 
static int num; 

public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_accounts); 

    webSite = (EditText) findViewById(R.id.editText2); 
    userName = (EditText) findViewById(R.id.editText3); 
    pass = (EditText) findViewById(R.id.editText4); 
    save = (Button) findViewById(R.id.save_button); 
    intent = getIntent(); 

    save.setOnClickListener(new View.OnClickListener() { 

     @Override 
     public void onClick(View v) { 

      SharedPreferences app_preferences = PreferenceManager 
        .getDefaultSharedPreferences(Accounts.this); 
      SharedPreferences.Editor editor = app_preferences.edit(); 
      int num; 
      num = app_preferences.getInt("Account_num", 0); 
      num++; 
      editor.putInt("Account_num", num); 
      String list = webSite.getText().toString(); 
      editor.putString("account_name_" + num, list); 
      editor.putString("account_user_" + num, userName.getText() 
        .toString()); 

      editor.putString("account_pass_" + num, pass.getText() 
        .toString()); 
      editor.commit(); 
      Intent myIntent = new Intent(Accounts.this, CreateAccount.class); 
      startActivity(myIntent); 

     } 

    }); 

    num = intent.getIntExtra("position", -1); 
    num++; 
    if (num != -1) { 

     String list = intent.getStringExtra("account_name_"); 
     preferences = PreferenceManager 
       .getDefaultSharedPreferences(Accounts.this); 
     webSite.setText(preferences.getString("account_name_" + num, 
       webSite.getText().toString())); 
     userName.setText(preferences.getString("account_user_" + num, 
       userName.getText().toString())); 
     pass.setText(preferences.getString("account_pass_" + num, pass 
       .getText().toString())); 
    } 
} 
} 

Answer 1

你的問題是，您更改與 「account_name_」 + NUM的關鍵。 SharedPreferences是一個關鍵的價值商店。如果將put方法應用於相同的鍵，則可以更改這些值。