Question

我是安乐斯和伊米的一位新来者,只是试图永久地储存地。

我想从<条码>参考性中提取这一条码,然后更新<条码>。

我正在阅读关于持久性储存的现有选择:。

I ve tried to use SharedPreferences but it s very unclear for me on how it should work.

我制作了非常简单的测试表。

MainActative.java

public class MainActivity extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
}

/* method that starts preferences */
public void openPreferences(View v) {
    Intent i = new Intent(this, Preferences.class);
    startActivity(i);
}

@Override
protected void onStart(){
    super.onStart();

    // Get preferences
    SharedPreferences preferences = getPreferences(0);
    String name = preferences.getString("name","Empty string!");

    // Create a RemoteViews layout
    RemoteViews views = new RemoteViews(getPackageName(),R.layout.main);       
    // set new text for labels
    views.setTextViewText(R.string.name, name);
}

@Override
protected void onStop(){
    super.onStop();

    // We need an Editor object to make preference changes.
    // All objects are from android.context.Context
    SharedPreferences preferences = getPreferences(0);
    SharedPreferences.Editor editor = preferences.edit();
    editor.putString("name", "This is a test");
    // Commit the edits!
    editor.commit();
}
}

Preferences.java

public class Preferences extends PreferenceActivity {
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            addPreferencesFromResource(R.xml.preferences);
        }
}

AndroidManifest.xml

<application android:icon="@drawable/icon" android:label="@string/app_name">
    <activity android:name=".MainActivity"
              android:label="@string/app_name">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity android:name=".Preferences" 
              android:label="@string/preferences_title">
    </activity>

</application>

The text of the TextView never changes, it is always set to the value I set on strings.xml.

你们能否帮助我了解我究竟做什么错了?

非常感谢。

Answer 1

你非常接近我的建议:

(1) 界定一些共同选择:

    public static final String MY_PREFERENCES = "MyPreferences";
    ...
    public static final SOME_PREFERENCE = "SomePreference";

2) 阅读来自共同选择

    SharedPreferences myPreferences;
    ...
    myPreferences = getSharedPreferences (MY_PREFERENCES, Context.MODE_PRIVATE);

3) 取消/更新共同的优惠:

    Editor editor = myPreferences.edit ();
    editor.putString (SOME_PREFERENCE, "abc");
    editor.commit ();

Answer 2

Quick example of saving/writing username, password into preferences.

SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(this);

Editor edit = preferences.edit();        
edit.putString("username", "abcd");        
edit.putString("password", "abcd#");        
edit.commit();

阅读用户名称的快速例子,优惠的密码。

SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(this);    

String strUsername = preferences.getString("username", null);   
String strPassword = preferences.getString("password", null);

Answer 3

我刚刚认识到了我有关<代码>的守则。共享参考书是正确的,但<编码>TextView从未更新过,因为我试图直接编辑自己,而不是“!

Just resolved this way:

    /* Update text of TextView */
    TextView t = (TextView) this.findViewById(R.id.name);
    // previously was R.string.name - not correct!
    t.setText(name);

许多人感谢您的帮助:

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