小编Jon*_*tis的帖子

我正在创建一个包含用户名和密码字段的登录窗口,每个我都想放置图标.当我向EditText字段添加图标时,我无法更改图标的大小.

图标在EditText字段内,因为我想在聚焦时更改EditText背景.

我试图将图标和EditText视图放在LinearLayout中,但是当EditText聚焦时我无法更改布局背景.

我的EditText代码:

<EditText
    android:id="@+id/user_name_edit_text"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_marginLeft="35dp"
    android:layout_marginRight="35dp"
    android:layout_marginTop="35dp"
    android:background="@drawable/custom_border_selector"
    android:drawablePadding="5dp"
    android:hint="@string/username"
    android:singleLine="true"
    android:textColor="#757575"
    android:textSize="15sp"
    android:drawableLeft="@drawable/ic_person_grey_24dp"
    />

EditText visual:

我是初学者程序员,只是怨恨开始android开发.看了很多答案,找不到女巫适合我的答案.我在操作栏中添加了后退箭头按钮,但无法弄清楚如何将导航添加到第一个加载的屏幕.

MainActivity.java

public class MainActivity extends AppCompatActivity
    implements NavigationView.OnNavigationItemSelectedListener {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    ActionBar actionBar = getSupportActionBar();

    if (actionBar != null){
        actionBar.setDisplayHomeAsUpEnabled(true);
        actionBar.setHomeButtonEnabled(true);
    }

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    final 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);

    getSupportFragmentManager().addOnBackStackChangedListener(new FragmentManager.OnBackStackChangedListener() {
        @Override
        public void onBackStackChanged() {
            toggle.setDrawerIndicatorEnabled(getSupportFragmentManager().getBackStackEntryCount() == 0);
        }
    });
}

@Override
public void onBackPressed() {
    DrawerLayout drawer …