Java 如何修复：多个片段和活动_main之间的事务？

当我打开导航抽屉并滚动浏览不同的选项时（让我们称它们为A、B和C）。当我点击A、B或C时，

片段

布局没有打开，我卡在我的

活动\u主

布局上

以前，我将我的

content\u main

和我的

Activity\u main

作为两个单独的XML文件，并且我被告知我必须将

content\u main

代码放入

Activity\u main

（我这样做了），这就删除了

找不到id

的错误

这是我的

活动\u main

（现在）：

---

我认为你不应该更换主要的活动布局。

---

如果您的主活动布局中有一个与其父级宽度和高度相匹配的视图（如框架布局），那就更好了。

您可以在执行片段事务的位置添加java文件吗？请输入java代码。首先，您需要重命名

Activity\u main.xml

以使其包含所有小写字母，即

Activity\u main.xml

。请提供用于

片段

事务的Java代码。添加了我的代码，希望对您有所帮助。关于Activity_main.xml，我实际上把它作为Activity_main.xml。很抱歉用大写字母，我不完全明白你想说什么。如果我不在主活动中使用.replace，那么我在片段之间切换将不起作用？？如果我误解了，请纠正我。

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout
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:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:openDrawer="start">

<include
    layout="@layout/app_bar_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

<android.support.design.widget.NavigationView
    android:id="@+id/nav_view"
    android:layout_width="wrap_content"
    android:layout_height="match_parent"
    android:layout_gravity="start"
    android:fitsSystemWindows="true"
    app:headerLayout="@layout/nav_header_main"
    app:menu="@menu/activity_main_drawer" />

<LinearLayout
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ImageView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:srcCompat="@drawable/e"
        android:id="@+id/imageView7"
        android:layout_marginTop="96dp"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:contentDescription=""/>

    <ImageView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:srcCompat="@drawable/welcome"
        android:id="@+id/imageView2"
        android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"/>
</LinearLayout>

package mcshreker.pocketmath;

import android.app.FragmentTransaction;
import android.os.Build;
import android.os.Bundle;
import android.support.annotation.IdRes;
import android.support.annotation.Nullable;
import android.support.annotation.RequiresApi;
import android.support.v4.app.FragmentManager;
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.text.Layout;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;

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);

    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();


    return super.onOptionsItemSelected(item);
}

@RequiresApi(api = Build.VERSION_CODES.M)
@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {
    // Handle navigation view item clicks here.
    int id = item.getItemId();
    FragmentManager fragmentManager = getSupportFragmentManager();

    if (id == R.id.nav_first_layout) {
        fragmentManager.beginTransaction().replace
                (R.id.drawer_layout, new firstFragment()).commit();

        // Handle the camera action

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

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

    } else if (id == R.id.nav_second_layout) {
        fragmentManager.beginTransaction().replace
                (R.id.drawer_layout, new secondFragment()).commit();
    } else if (id == R.id.nav_third_layout) {
        fragmentManager.beginTransaction().replace
                (R.id.drawer_layout, new thirdFragment()).commit();
    } else if (id == R.id.nav_fourth_layout) {
        fragmentManager.beginTransaction().replace
                (R.id.drawer_layout, new fourthFragment()).commit();
    } else if (id == R.id.nav_fifth_layout) {
        fragmentManager.beginTransaction().replace
                (R.id.drawer_layout, new fifthFragment()).commit();
    } else if (id == R.id.nav_sixth_layout) {
        fragmentManager.beginTransaction().replace
                (R.id.drawer_layout, new sixthFragment()).commit();
    } else if (id == R.id.nav_seventh_layout) {
        fragmentManager.beginTransaction().replace
                (R.id.drawer_layout, new seventhFragment()).commit();
    } else if (id == R.id.nav_eighth_layout) {
        fragmentManager.beginTransaction().replace
                (R.id.drawer_layout, new eighthFragment()).commit();
    } else if (id == R.id.nav_ninth_layout) {
        fragmentManager.beginTransaction().replace
                (R.id.drawer_layout, new ninthFragment()).commit();
    }

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