使用 Intent 和 SharedPreferences 在 onResume() 中处理切换状态

Question

我编写了一个程序，我在其中使用 Timer 并使用 Toggle 状态控制该计时器，

喜欢：我的 Toggle 的默认状态是 OFF，一旦我将切换状态从 OFF 更改为 ON，TIMER 就会启动，当我再次更改为 OFF 时，它会根据要求停止计时器。

但是当我的计时器打开并且我切换到其他活动然后再次返回到切换活动然后将切换状态从开启更改为关闭时，问题就开始了 - 它仍然运行计时器...

ToggleActivity.java：

public class ToggleActivity extends Activity implements OnCheckedChangeListener {

    ToggleButton toggleButton;
    TextView text;

    Timer timer;
    TimerTask timerTask;
    final Handler handler = new Handler();

    Button btnSwitchActivity;

    boolean toggleState;
    SharedPreferences sharedPreferences;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_toggle);           

        toggleButton = (ToggleButton) findViewById(R.id.toggleButton);
        text = (TextView) findViewById(R.id.textView1);
        btnSwitchActivity = (Button) findViewById(R.id.btnSwitchActivity);

        sharedPreferences = getApplicationContext().getSharedPreferences("toggleState",0);

        toggleButton.setOnCheckedChangeListener(this);

        btnSwitchActivity.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                Intent intentSwitchActivity = new Intent(ToggleActivity.this, SwitchActivity.class);
                startActivity(intentSwitchActivity);
                }
            });

        }

        @Override
        public void onCheckedChanged(CompoundButton arg0, boolean isChecked) {      

            if(isChecked)
            {               
                SharedPreferences.Editor editor = sharedPreferences.edit();
                editor.putBoolean("toggleState", true);
                editor.commit();

                text.setText("ON");

                startTimer();

            } else 
            {       

                SharedPreferences.Editor editor = sharedPreferences.edit();
                editor.putBoolean("toggleState", false);
                editor.commit();

                text.setText("OFF");

                if (timer != null) {
                    timer.cancel();
                    timer = null;
                }
            }

        }


        public void startTimer() {

            timer = new Timer();            
            initializeTimerTask();          
            timer.schedule(timerTask, 1000, 5000);

        }

        public void stoptimertask(View v) {

            if (timer != null) {
                timer.cancel();
                timer = null;
            }

        }

        public void initializeTimerTask() {

            timerTask = new TimerTask() {

                public void run() {

                    handler.post(new Runnable() {

                        public void run() {
                            Calendar calendar = Calendar.getInstance();
                            SimpleDateFormat simpleDateFormat = new SimpleDateFormat("dd:MMMM:yyyy HH:mm:ss a");
                            final String strDate = simpleDateFormat.format(calendar.getTime());

                            int duration = Toast.LENGTH_SHORT;  
                            Toast toast = Toast.makeText(getApplicationContext(), strDate, duration);
                            toast.show();
                        }

                    });

                }

            };

        }

        public void onResume() {
            super.onResume();

            toggleState = sharedPreferences.getBoolean("toggleState", false);
            Log.v("toggleState-onResume()", Boolean.toString(toggleState));
            if (toggleState) {
                toggleButton.setChecked(true);
            } else {
                toggleButton.setChecked(false);
            }

        }

}

SwitchActivity.java：

public class SwitchActivity extends Activity {

    Button btnToggleActivity;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_switch);

        btnToggleActivity = (Button) findViewById(R.id.btnToggleActivity);
        btnToggleActivity.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                Intent intent = new Intent(SwitchActivity.this, ToggleActivity.class);
                startActivity(intent);
                /**
                 * if i use finish() instead of Intent to switch to ToggleActivity 
                 * my Timer works fine
                 */
                // finish
            }
        });
    }

}

activity_toggle.xml：

<LinearLayout 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:gravity="center"
    android:background="#ffffff"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:orientation="vertical"
    tools:context=".ToggleActivity" >

    <ToggleButton
        android:id="@+id/toggleButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@drawable/toggle_selector"
        android:checked="false"
        android:text=""
        android:textOff=""
        android:textOn="" />

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"        
        android:layout_marginTop="20dp"
        android:layout_marginBottom="20dp"
        android:text="@string/string_toggle_off"
        android:textAppearance="?android:attr/textAppearanceMedium" />

    <Button 
        android:id="@+id/btnSwitchActivity"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/string_btn_switch"/>

</LinearLayout>

activity_switch.xml：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:background="#ffffff"
    android:orientation="vertical" >

    <Button 
        android:id="@+id/btnToggleActivity"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/string_btn_goback"
        />

</LinearLayout>

Answer 1

您可能应该通过覆盖 onSaveInstanceState 来将切换按钮的状态保存在 savedInstanceState 包中。

@Override
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        outstate.putBoolean("KEY", yourButton.isToggle())
    }

然后您可以通过阅读在活动的 onCreate 中提供给您的 savedInstanceState 包来访问它，或者如果您在片段中工作，则可以通过 onCreateView/onViewCreated 来访问它。

希望这会有所帮助。