我们如何让 Activity 在启动时默认出现？

Question

我制作了一个带有导航抽屉的应用程序，其启动时的默认 activity 是 HomeActivity。我希望 UserActivity 在启动时默认启动。我试着用 AndroidManifest.xml 来做，但没有用。你能告诉我另一种方法吗，比如在 HomeActivity 中使用 intent 或其他东西，以便它在应用程序打开时立即加载到 UserActivity？

HomeActivity.java

package thenerdimite.nuttybuddies;

import android.app.Activity;
import android.app.Fragment;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.view.LayoutInflater;
import android.view.View;
import android.support.design.widget.NavigationView;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.view.ViewGroup;

public class HomeActivity extends AppCompatActivity
        implements NavigationView.OnNavigationItemSelectedListener {

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

    @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.home, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    @SuppressWarnings("StatementWithEmptyBody")
    @Override
    public boolean onNavigationItemSelected(MenuItem item) {
        // Handle navigation view item clicks here.
        int id = item.getItemId();
        android.app.FragmentManager fragmentmanager = getFragmentManager();
        if (id == R.id.nav_activity_user) {
            fragmentmanager.beginTransaction()
                    .replace(R.id.content_frame
                            , new UserActivity())
                    .commit ();
        } else if (id == R.id.nav_activity_blog) {
            fragmentmanager.beginTransaction()
                    .replace(R.id.content_frame
                            , new BlogActivity())
                    .commit ();
        } else if (id == R.id.nav_activity_Chat) {
            fragmentmanager.beginTransaction()
                    .replace(R.id.content_frame
                            , new ChatActivity())
                    .commit ();
        } else if (id == R.id.nav_activity_fbgroup) {
            fragmentmanager.beginTransaction()
                    .replace(R.id.content_frame
                            , new FBGroupActivity())
                    .commit ();

        } else if (id == R.id.nav_share) {

        } else if (id == R.id.nav_send) {

        }

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

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="thenerdimite.nuttybuddies">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity
            android:name=".HomeActivity"
            android:label="@string/app_name"
            android:theme="@style/AppTheme.NoActionBar">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".BlogActivity" />
        <activity android:name=".ChatActivity" />
        <activity android:name=".FBGroupActivity" />
        <activity android:name=".UserActivity"></activity>
    </application>

</manifest>

UserActivity.java

package thenerdimite.nuttybuddies;

import android.app.Fragment;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class UserActivity extends Fragment {

    View myView;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, Bundle savedInstanceState) {
        myView = inflater.inflate(R.layout.activity_user, container, false);
        return myView;
    }
}

activity_home_drawer.xml

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">

    <group android:checkableBehavior="single">
        <item
            android:id="@+id/nav_activity_user"
            android:icon="@drawable/ic_menu_camera"
            android:title="Home" />
        <item
            android:id="@+id/nav_activity_blog"
            android:icon="@drawable/ic_menu_gallery"
            android:title="Blog" />
        <item
            android:id="@+id/nav_activity_Chat"
            android:icon="@drawable/ic_menu_slideshow"
            android:title="Chat Room" />
        <item
            android:id="@+id/nav_activity_fbgroup"
            android:icon="@drawable/ic_menu_manage"
            android:title="Facebook Group" />
    </group>

    <item android:title="Communicate">
        <menu>
            <item
                android:id="@+id/nav_share"
                android:icon="@drawable/ic_menu_share"
                android:title="About Us" />
            <item
                android:id="@+id/nav_send"
                android:icon="@drawable/ic_menu_send"
                android:title="Click Here to Report App related Issues" />
        </menu>
    </item>

</menu>

任何帮助都会很棒。谢谢！

Answer 1

在 AndroidManifest 中删除这个

<intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter>

并将其添加到您要在开始时显示的activity

Answer 2

你好@Bhavesh 我以为你正在使用片段所以你不需要在清单中声明只需将最后放在你将在 UserActivity 中的创建方法中

getSupportFragmentManager().beginTransaction()
                .replace(R.id.content_frame, new UserActivity())
                .commit();

Answer 3

在HomeActivity的OnCreate中添加onNavigationItemSelected

public class HomeActivity extends AppCompatActivity
    implements NavigationView.OnNavigationItemSelectedListener {

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

 ......


 ......

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

 if (savedInstanceState == null) {
          MenuItem item =  navigationView.getMenu().getItem(0);
          onNavigationItemSelected(item);
    }
  }
}

并从 AndroidManifest.xml

中删除这一行

<activity android:name=".UserActivity"></activity>

我们如何让 Activity 在启动时默认出现？

How can we make an Activity appear by default at launch?

android

android-activity

android-manifest

launching-application