Question

我有一个选项菜单。当活动失去焦点时，所选的选项菜单项保持状态，但当我的活动被销毁时，所有选项都将被重置。

如何从销毁状态恢复后保存所选首选项的状态？有问题可视化如何为代码实现Shared Preferences。

（只有布尔值需要，但我已经包含了静态菜单项。）

public final static int MENU_SOMETHING_MODE_ON = 1;
public final static int MENU_SOMETHING_MODE_OFF = 2;
public final static int MENU_FULLSCREEN_ON = 3;
public final static int MENU_FULLSCREEN_OFF = 4;
public final static int MENU_SOUND_ON = 5;
public final static int MENU_SOUND_OFF = 6;
public final static int MENU_FASTER = 7;
public final static int MENU_SLOWER = 8;
public final static int MENU_SOMETHING = 9;
public final static int MENU_EXTRAS = 10;

private static boolean soundOn = true;
private static boolean mFaster = true;

private boolean fullscreen = true;

@Override
public boolean onCreateOptionsMenu(Menu menu)
{
    super.onCreateOptionsMenu(menu);
    menu.add(0, MENU_SOMETHING, 0, R.string.menu_new_something);
    menu.add(0, MENU_SOMETHING_MODE_ON, 0,
             R.string.menu_something_on);
    menu.add(0, MENU_SOMETHING_MODE_OFF, 0,
             R.string.menu_something_off);
    menu.add(0, MENU_FULLSCREEN_ON, 0, R.string.menu_fullscreen_on);
    menu.add(0, MENU_FULLSCREEN_OFF, 0, R.string.menu_fullscreen_off);
    menu.add(0, MENU_SOUND_ON, 0, R.string.menu_sound_on);
    menu.add(0, MENU_SOUND_OFF, 0, R.string.menu_sound_off);
    menu.add(0, MENU_FASTER, 0, R.string.menu_faster);
    menu.add(0, MENU_SLOWER, 0, R.string.menu_slower);
    menu.add(0, MENU_EXTRAS, 0, R.string.menu_extras);
    return true;
}

@Override
public boolean onPrepareOptionsMenu(Menu menu)
{
    super.onPrepareOptionsMenu(menu);
    menu.findItem(MENU_SOUND_ON).setVisible(!getSoundOn());
    menu.findItem(MENU_SOUND_OFF).setVisible(getSoundOn());
    menu.findItem(MENU_SOMETHING_ON).setVisible(
        getMode() == SOMETHING_NORMAL);
    menu.findItem(MENU_SOMETHING_OFF).setVisible(
        getMode() != SOMETHING_NORMAL);
    menu.findItem(MENU_FULLSCREEN_ON).setVisible(!fullscreen);
    menu.findItem(MENU_FULLSCREEN_OFF).setVisible(fullscreen);
    menu.findItem(MENU_FASTER).setVisible(getFaster());
    menu.findItem(MENU_SLOWER).setVisible(!getFaster());
    return true;
}


@Override
public boolean onOptionsItemSelected(MenuItem item)
{
    switch (item.getItemId()) {
    case MENU_SOMETHING:

     AlertDialog.Builder alt_bld = new AlertDialog.Builder(this);   

     alt_bld.setMessage("Are you sure?")
     .setCancelable(false)
     .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
             public void onClick(DialogInterface dialog, int id) {
                 //  Action for 'YES' Button
                 something.new();
             }
      })
     .setNegativeButton("No", new DialogInterface.OnClickListener() {
             public void onClick(DialogInterface dialog, int id) {
                 //  Action for 'NO' Button
                 dialog.cancel();
             }
      });
      AlertDialog alert = alt_bld.create();
      // Title for AlertDialog
      alert.setTitle("Something");
      // Icon for AlertDialog
      alert.setIcon(R.drawable.dialog);
      alert.show();


      return true;
    case MENU_SOMETHING_ON:
      setMode(THIS_SOMETHING);
      return true;
    case MENU_SOMETHING_OFF:
      setMode(THIS_NORMAL);
      return true;
    case MENU_FULLSCREEN_ON:
      fullscreen = true;
      setFullscreen();
      return true;
    case MENU_FULLSCREEN_OFF:
      fullscreen = false;
      setFullscreen();
      return true;
    case MENU_SOUND_ON:
      setSoundOn(true);
      return true;
    case MENU_SOUND_OFF:
      setSoundOn(false);
      return true;
    case MENU_FASTER:
      setFaster(false);
      return true;
    case MENU_SLOWER:
      setSlower(true);
      return true;
    case MENU_EXTRAS:
      startExtras();
      return true;
    }
    return false;
}

private void setFullscreen()
{
    if (fullscreen) {
      getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);
      getWindow().clearFlags(
          WindowManager.LayoutParams.FLAG_FORCE_NOT_FULLSCREEN);
    } else {
      getWindow().clearFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);
      getWindow().addFlags(
          WindowManager.LayoutParams.FLAG_FORCE_NOT_FULLSCREEN);
    }
    mView.requestLayout();
}

public synchronized static void setMode(int newMode)
{
    Mode = newMode;
}

public synchronized static int getMode()
{
    return Mode;
}

public synchronized static boolean getSoundOn()
{
    return soundOn;
}

public synchronized static void setSoundOn(boolean so)
{
    soundOn = so;
}

public synchronized static boolean getFaster()
{
    return Faster;
}

public synchronized static void setFaster(boolean dont)
{
    Faster = dont;
}

Answer 1

This is a fantastic tutorial关于如何创建偏好活动以及如何获取/设置这些偏好。如果您选择不实施偏好活动，它还将向您展示如何使用共享偏好。

几乎所有用户都熟悉偏好活动，因为这是他们调整手机设置的方式。

虽然不是实施“选项”的唯一方式，或者甚至可能不是最佳方式，但它运行良好，具有很大的灵活性，并且实现简单快捷。

保存选项菜单共享首选项

1 个答案: