我的导航抽屉出现问题,我想将FragHome
设置为我的默认启动主页。但我不能在这里实现它是我的代码:
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_nav);
activity = this;
auth = FirebaseAuth.getInstance();
dl = findViewById(R.id.nav_drawer);
dl.setVerticalScrollBarEnabled(false);
toggle = new ActionBarDrawerToggle(this, dl, R.string.nav_drawer_open, R.string.nav_drawer_close);
NavigationView nv = findViewById(R.id.nav);
nv.setCheckedItem(R.id.nav_home);
nv.setVerticalScrollBarEnabled(false);
dl.addDrawerListener(toggle);
toggle.syncState();
if (getSupportActionBar() != null) {
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
}
setContent(nv);
}
public static void finishThis() {
try {
if (activity != null) {
activity.finish();
}
} catch (Exception ex) {
ex.printStackTrace();
}
}
public void showHome() {
fragment = new FragHome();
if (fragment != null) {
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.replace(R.id.nav_home, fragment,fragment.getTag());
ft.commit();
}
}
public void onDisplay(View v) {
startActivity(new Intent(NavActivity.this, FragInfo.class));
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
if (toggle.onOptionsItemSelected(item)) {
return true;
}
return super.onOptionsItemSelected(item);
}
Fragment fragment = null;
public void selectItem(MenuItem i) {
switch (i.getItemId()) {
case R.id.nav_home:
fragment = new FragHome();
break;
case R.id.nav_eng:
fragment = new FragEng();
break;
case R.id.nav_math:
fragment = new FragMath();
break;
case R.id.nav_sci:
fragment = new FragSci();
break;
case R.id.nav_his:
fragment = new FragHistory();
break;
case R.id.exam:
fragment = new examMain();
break;
case R.id.nav_about:
fragment = new FragAbout();
break;
case R.id.nav_logout:
AlertDialog.Builder builder = new AlertDialog.Builder(this, R.style.navDialog);
builder.setMessage("Are you sure you want to log out?")
.setCancelable(false)
.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
if (auth.getCurrentUser() != null)
auth.signOut();
Intent intent = new Intent(NavActivity.this, LoginActivity.class);
startActivity(intent);
finish();
}
})
.setNegativeButton("No", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
dialog.cancel();
}
});
AlertDialog alert = builder.create();
alert.show();
default:
fragment = new FragHome();
}
if (fragment != null) {
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.replace(R.id.nav_home, fragment);
ft.commit();
}
DrawerLayout drawer = findViewById(R.id.nav_drawer);
drawer.closeDrawer(GravityCompat.START);
}
private void setContent(NavigationView v) {
v.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {
@Override
public boolean onNavigationItemSelected(@NonNull MenuItem item) {
selectItem(item);
return true;
}
});
}
@Override
public void onBackPressed() {
//You may also add condition if (doubleBackToExitPressedOnce || fragmentManager.getBackStackEntryCount() != 0) // in case of Fragment-based add
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.nav_drawer);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
if(fragment instanceof FragHome){
super.onBackPressed();
}else {
showHome();
}
}
}
}
答案 0 :(得分:1)
你永远不会在onCreate()中调用showHome()。参见下面的例子。
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_nav);
activity = this;
auth = FirebaseAuth.getInstance();
dl = findViewById(R.id.nav_drawer);
dl.setVerticalScrollBarEnabled(false);
toggle = new ActionBarDrawerToggle(this, dl, R.string.nav_drawer_open, R.string.nav_drawer_close);
NavigationView nv = findViewById(R.id.nav);
nv.setCheckedItem(R.id.nav_home);
nv.setVerticalScrollBarEnabled(false);
dl.addDrawerListener(toggle);
toggle.syncState();
if (getSupportActionBar() != null) {
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
}
setContent(nv);
showHome();
}
答案 1 :(得分:0)
你可以参加活动。
@Override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
FragmentTransaction tx = getSupportFragmentManager().beginTransaction();
tx.replace(R.id.content_frame, new FragmentA());
tx.commit();
}
private class DrawerItemClickListener implements ListView.OnItemClickListener {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
selectItem(position);
}
}
/** Swaps fragments in the main content view */
private void selectItem(int position) {
// Create a new fragment and specify the planet to show based on position
Fragment fragment = new PlanetFragment();
Bundle args = new Bundle();
args.putInt(PlanetFragment.ARG_PLANET_NUMBER, position);
fragment.setArguments(args);
// Insert the fragment by replacing any existing fragment
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction()
.replace(R.id.content_frame, fragment)
.commit();
// Highlight the selected item, update the title, and close the drawer
mDrawerList.setItemChecked(position, true);
setTitle(mPlanetTitles[position]);
mDrawerLayout.closeDrawer(mDrawerList);
}
@Override
public void setTitle(CharSequence title) {
mTitle = title;
getActionBar().setTitle(mTitle);
}
你必须看到绘制片段和导航的基本教程。 https://developer.android.com/training/implementing-navigation/nav-drawer.html