Question

我正在使用android Navigation抽屉模板和片段来显示不同的视图。

正常情况下会自动生成MainActivity，activity_main.xml和content_main.xml。

我创建了两个java类; MusicFragment和MainFragment，当然还有我内容中的布局文件。

当我运行应用程序时，activity_main是启动的默认布局，我有欢迎内容显示，我使用导航抽屉导航到我的MusicFragment和MainFragment，这个代码用于替换onNavigationItemSelected方法中的当前视图是;

 if (id == R.id.nav_camara) {

        fm.beginTransaction().replace(R.id.content_frame, new MainFragment()).commit();


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

        fm.beginTransaction().replace(R.id.content_frame, new MusicFragment()).commit();

虽然我有一个很大的问题，但是当我选择导航抽屉并点击相机选项它显示片段视图但不替换来自activity_main的内容时，这两个都可以正常替换彼此，但是它显示了片段内容。 content_main并没有替换它。

这是我的MainActivity：

package com.justmikey.justmik;

import android.media.MediaPlayer;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v4.app.FragmentManager;
import android.support.v7.internal.widget.ButtonBarLayout;
import android.text.method.ScrollingMovementMethod;
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.widget.Button;
import android.widget.TextView;
import JustMikey.Fragments.MainFragment;
import JustMikey.Fragments.MusicFragment;

public class MainActivity extends AppCompatActivity
    implements NavigationView.OnNavigationItemSelectedListener {

//create a media player object called mp
MediaPlayer mp;
//declare my buttons play, pause and stop
Button play, pause,stop;

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

    //Set the textView scrollMain to scrollable
    TextView tv = (TextView) findViewById(R.id.scrollMain);
    tv.setMovementMethod(new ScrollingMovementMethod());

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

    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.main, 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) {
    android.app.FragmentManager fm = getFragmentManager();

    int id = item.getItemId();

    if (id == R.id.nav_camara) {

        fm.beginTransaction().replace(R.id.content_frame, new MainFragment()).commit();


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

        fm.beginTransaction().replace(R.id.content_frame, new MusicFragment()).commit();


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

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

    } 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;
}
}

content_main.xml：

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



<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"     android:layout_width="match_parent"
android:layout_height="match_parent"         android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
app:layout_behavior="@string/appbar_scrolling_view_behavior" tools:showIn="@layout/app_bar_main"
tools:context=".MainActivity"
android:background="#dbe4eb">



<FrameLayout
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:id="@+id/content_frame">

    <ImageView
        android:layout_width="355dp"
        android:layout_height="wrap_content"
        android:src="@drawable/jmmain"
        android:id="@+id/imageView2"
        android:layout_gravity="center_horizontal|top"
        android:layout_alignRight="@+id/content_frame"
        android:layout_alignEnd="@+id/content_frame" />

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="274dp"
        android:text="hello hello hello hello hello hello hello hello"
        android:id="@+id/scrollMain"
        android:layout_gravity="center_horizontal|bottom"
        android:layout_alignBottom="@+id/scrollView"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_marginBottom="28dp"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true"
        android:background="#ffffff"
        android:padding="10dp"
        />

    <ScrollView
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:id="@+id/scrollView"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_gravity="center">

    </ScrollView>


</FrameLayout>

</RelativeLayout>

Answer 1

FragmentTransaction只处理Fragment。他们不会替换/删除Fragment以外的任何内容。由于View content_frame中包含的FrameLayout仅在启动时需要，因此我们可以在第一个FragmentTransaction上删除它们。

为此，我们会创建一个成员boolean标记isStartup，初始化为true。在onNavigationItemSelected()方法中，我们会检查标记，如果是true，则删除View并将其更改为false。< / p>

声明并初始化任何方法之外的布尔值：

private boolean isStartup = true;

然后使用onNavigationItemSelected()方法进行检查和删除。

public boolean onNavigationItemSelected(MenuItem item) {
    android.app.FragmentManager fm = getFragmentManager();
    int id = item.getItemId();

    if(isStartup) {
        ((FrameLayout) findViewById(R.id.content_frame)).removeAllViews();
        isStartup = false;
    }

    if (id == R.id.nav_camara) {
        ...

}

Answer 2

我遇到了同样的问题。我无法用上述解决方案解决我的问题。但我找到了两种解决方案来解决它！

1-您可以将主页面的内容显示在其他视图组中。并将其隐藏在onNavigationItemSelected中，位于正确的位置：

content_main.xml：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#dbe4eb"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:context=".MainActivity"
tools:showIn="@layout/app_bar_main">

<FrameLayout
    android:id="@+id/content_frame"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

<LinearLayout
    android:id="@+id/my_linearLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <ImageView
        android:id="@+id/imageView2"
        android:layout_width="355dp"
        android:layout_height="wrap_content"
        android:layout_alignEnd="@+id/content_frame"
        android:layout_alignRight="@+id/content_frame"
        android:layout_gravity="center_horizontal|top"
        android:src="@drawable/jmmain" />

    <TextView
        android:id="@+id/scrollMain"
        android:layout_width="fill_parent"
        android:layout_height="274dp"
        android:layout_alignBottom="@+id/scrollView"
        android:layout_alignParentEnd="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentRight="true"
        android:layout_alignParentStart="true"
        android:layout_gravity="center_horizontal|bottom"
        android:layout_marginBottom="28dp"
        android:background="#ffffff"
        android:padding="10dp"
        android:text="hello hello hello hello hello hello hello hello" />

    <ScrollView
        android:id="@+id/scrollView"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_gravity="center"></ScrollView>
</LinearLayout>
</RelativeLayout>

MainActivity.java中的onNavigationItemSelected方法：

public boolean onNavigationItemSelected(MenuItem item) {
    // Handle navigation view item clicks here.
    int id = item.getItemId();

    if (id == R.id.main) {
        findViewById(R.id.my_linearLayout).setVisibility(View.VISIBLE);
        fragmentManager.popBackStack("fragment", POP_BACK_STACK_INCLUSIVE);
    } else if (id == R.id.one) {
        findViewById(R.id.my_linearLayout).setVisibility(View.GONE);
        fragmentManager.beginTransaction().replace(R.id.content_frame, new OneFragment()).addToBackStack("fragment").commit();
    } else if (id == R.id.tow) {
        findViewById(R.id.my_linearLayout).setVisibility(View.GONE);
        fragmentManager.beginTransaction().replace(R.id.content_frame, new SecondFragment()).addToBackStack("fragment").commit();
    }

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

2-第二种方法是考虑主页内容的片段。然后在onNavigationItemSelected方法中，我们将其视为与其他片段一样：

MainActivity.java中的onNavigationItemSelected方法：

    public boolean onNavigationItemSelected(MenuItem item) {
    // Handle navigation view item clicks here.
    int id = item.getItemId();

    if (id == R.id.main) {
        fragmentManager.beginTransaction().replace(R.id.content_frame, new HomeFragment()).addToBackStack("fragment").commit();
    } else if (id == R.id.one) {
        fragmentManager.beginTransaction().replace(R.id.content_frame, new OneFragment()).addToBackStack("fragment").commit();
    } else if (id == R.id.tow) {
        fragmentManager.beginTransaction().replace(R.id.content_frame, new SecondFragment()).addToBackStack("fragment").commit();
    }

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

注意：要在打开程序时显示主页面的内容，请在MainActivity中的onCreate（）中输入以下代码：

        fragmentManager.beginTransaction().replace(R.id.content_frame, new HomeFragment()).addToBackStack("fragment").commit();

替换导航抽屉中的片段视图的问题

2 个答案: