public class ActivityCollector {

    private static List<Activity> activities = new ArrayList<Activity>();

    public static void addActivity(Activity activity) {
        activities.add(activity);
    }

    public static void removeActivity(Activity activity) {
        activities.remove(activity);
    }

    public static void finishAll() {
        for (Activity activity : activities) {
            activity.finish();
        }
    }
}

public class BaseActivity extends AppCompatActivity {

    private ForceOfflineReceiver receiver;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ActivityCollector.addActivity(this);
    }

    @Override
    protected void onResume() {
        super.onResume();
        IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction("com.example.broadcastbestpractice.FORCE_OFFLINE");
        receiver = new ForceOfflineReceiver();
        registerReceiver(receiver,intentFilter);
    }

    @Override
    protected void onPause() {
        super.onPause();
        if(receiver != null){
            unregisterReceiver(receiver);
            receiver = null;
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        ActivityCollector.removeActivity(this);
    }

    class ForceOfflineReceiver extends BroadcastReceiver {
        @Override
        public void onReceive(Context context, Intent intent) {
            AlertDialog.Builder builder = new AlertDialog.Builder(context);
            builder.setTitle("warning");
            builder.setMessage(" 拜拜了您勒");
            builder.setCancelable(false);
            builder.setPositiveButton("OJBK", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    ActivityCollector.finishAll();
                    Intent i = new Intent(context,LoginActivity.class);
                    context.startActivity(i);
                }
            });
            builder.show();
        }
    }
}

public class LoginActivity extends BaseActivity {
    private EditText accoutEdit;
    private EditText passwordEdit;
    private Button login;

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

        accoutEdit=(EditText) findViewById(R.id.accout);
        passwordEdit=(EditText) findViewById(R.id.password);
        login = (Button)  findViewById(R.id.login);

        login.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v) {
                String account = accoutEdit.getText().toString();
                String password = passwordEdit.getText().toString();
                if(account.equals("") || password.equals("")){
                    Toast.makeText(LoginActivity.this,"请输入完整的内容",Toast.LENGTH_SHORT).show();
                }
                if(account.equals("gzh666") && password.equals("123456")){
                    Intent intent = new Intent(LoginActivity.this,MainActivity.class);
                    startActivity(intent);
                    finish();
                }else {
                    Toast.makeText(LoginActivity.this," 密码或者账号错误",Toast.LENGTH_SHORT).show();
                }


            }
        });

public class MainActivity extends BaseActivity {

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

        Button forceOffline  = (Button) findViewById(R.id.force_offline);
        forceOffline.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v) {
                Intent intent = new Intent("com.example.broadcastbestpractice.FORCE_OFFLINE");
                sendBroadcast(intent);
            }
        });

    }
}

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/b">

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="60dp">

        <TextView
            android:layout_gravity="center_vertical"
            android:layout_width="90dp"
            android:layout_height="wrap_content"
            android:text="账号:"
            android:textSize="18sp"/>
        <EditText
            android:id="@+id/accout"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:layout_gravity="center_vertical"/>
    </LinearLayout>

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="60dp">

        <TextView
            android:layout_gravity="center_vertical"
            android:layout_width="90dp"
            android:layout_height="wrap_content"
            android:text="密码:"
            android:textSize="18sp"/>
        <EditText
            android:id="@+id/password"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:layout_gravity="center_vertical"
            android:inputType="textPassword"/>
    </LinearLayout>

    <Button
        android:id="@+id/login"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:text="登陆"/>

</LinearLayout>

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

    <Button
        android:id="@+id/force_offline"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="下机下机 回家睡觉"/>



</LinearLayout>

class Solution {
    public int[] twoSum(int[] numbers, int target) {
        int left=0,right=numbers.length-1;
        while( numbers[left]+numbers[right] != target){
            if( (numbers[left]+numbers[right])>target ){
                right--;
            }else if((numbers[left]+numbers[right])<target){
                left++;
            }else {
                return new int[]{left+1,right+1};
            }
        }   
        return  new int[]{left+1,right+1};
    }
}