Question

我是Android开发新手，我想在我的代码中添加time picker。我遵循了相同的教程，但是当我使用模拟器时，它不起作用。即使genymotion告诉我，我的应用程序执行存在问题（我的代码中没有错误），当我将showTimePickerDialog()放入onCreate()时，错误就开始了。这是我的代码：

public class MainActivity extends AppCompatActivity
        implements NavigationView.OnNavigationItemSelectedListener {
    Button button_stpd;
    static final int DIALOG_ID = 0 ;
    int hour_x;
    int minute_x ;

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

         showTimePickerDialog();
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
            setSupportActionBar(toolbar);


        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
            fab.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                            .setAction("Action", null).show();
                }
            });

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        drawer.setDrawerListener(toggle);
            toggle.syncState();

        NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);

        FragmentManager fm = getFragmentManager();
        fm.beginTransaction().replace(R.id.Acceuil, new Acceuil()).commit();

            showTimePickerDialog();
    }

    public void showTimePickerDialog(){
        button_stpd = (Button)findViewById(R.id.temps_btn);
        button_stpd.setOnClickListener(
                new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        showDialog(DIALOG_ID);
                    }
                }
        );

    }

    @Override
    protected Dialog onCreateDialog (int id){
        if (id == DIALOG_ID)
            return new TimePickerDialog(MainActivity.this, kTimePickerListner,hour_x,minute_x,false);
        return null;
    }

    protected TimePickerDialog.OnTimeSetListener kTimePickerListner =
            new TimePickerDialog.OnTimeSetListener() {
                @Override
                public void onTimeSet(TimePicker view, int hourOfDay, int minute) {
                    hour_x = hourOfDay;
                    minute_x = minute;
                    Toast.makeText(MainActivity.this,hour_x + ":"+minute_x, Toast.LENGTH_SHORT).show();
                }
            };


    @Override
    public void onBackPressed() {
        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        if (drawer.isDrawerOpen(GravityCompat.START)) {
            drawer.closeDrawer(GravityCompat.START);
        } else {
            super.onBackPressed();
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }



    @SuppressWarnings("StatementWithEmptyBody")
    @Override
    public boolean onNavigationItemSelected(MenuItem item) {
        // Handle navigation view item clicks here.
        int id = item.getItemId();
        FragmentManager fragmentManager = getFragmentManager() ;



        if (id == R.id.nav_Acceuil) {
            fragmentManager.beginTransaction().replace(R.id.Acceuil, new Acceuil()).commit() ;
            // Handle the camera action
        } else if (id == R.id.nav_Messagerie) {
            fragmentManager.beginTransaction().replace(R.id.Acceuil, new Messagerie()).commit() ;


        } else if (id == R.id.nav_Notification){
            fragmentManager.beginTransaction().replace(R.id.Acceuil, new Notification()).commit() ;


        } else if (id == R.id.nav_Paramétres) {
            fragmentManager.beginTransaction().replace(R.id.Acceuil, new Parametre()).commit() ;

        }
        else if (id == R.id.nav_Calories) {
            fragmentManager.beginTransaction().replace(R.id.Acceuil, new Calcule()).commit() ;

        }

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        drawer.closeDrawer(GravityCompat.START);
        return true;
    }

}

Answer 1

  button_stpd = (Button)findViewById(R.id.temps_btn);
    button_stpd.setOnClickListener(...

此代码将您在Java代码中使用的Button与您在xml布局中的Button相关联。这样的代码应该只写一次，因为它是你的一部分你使用两次的showTimePickerDialog（）方法，这是个大问题。

如果你想用另一种方法进行启动，以便onCreate看起来干净，那很好，但只使用该方法一次。例如，它可以被称为initiateViews（），您可以在其中执行以下操作：

 button_stpd = (Button)findViewById(R.id.temps_btn);
 button_stpd.setOnClickListener(... 
 Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
 setSupportActionBar(toolbar);

但是，根据我的理解，第二次使用showTimePickerDialog()时，您真正想要的是showDialog(DIALOG_ID);

时间选择器android

1 个答案: