ToolbarLayout、AppBarLayout和NestedScrollView组合实现的滑动折叠及遇到的问题

布局activity_main.xml

<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/main_content"
    android:layout_width="match_parent"
    android:layout_height="match_parent">


    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        
        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary"
            app:layout_scrollFlags="scroll|enterAlways">

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="match_parent"
                android:layout_gravity="center"
                android:gravity="center"
                android:text="自定义标题" />
        android.support.v7.widget.Toolbar>
        
        <ImageView
            android:layout_width="match_parent"
            android:layout_height="200dp"
            android:background="@mipmap/c_head2" />
        
        <android.support.design.widget.TabLayout
            android:id="@+id/tabLayout"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="#80ffffff"
            app:tabIndicatorColor="@color/colorAccent"
            app:tabMode="scrollable"
            app:tabSelectedTextColor="@color/colorAccent"
            app:tabTextColor="@android:color/black" />
    android.support.design.widget.AppBarLayout>

    <android.support.v4.widget.NestedScrollView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:overScrollMode="never"
     app:layout_behavior="@string/appbar_scrolling_view_behavior">

        <LinearLayout
            android:id="@+id/ll_sc_content"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical">LinearLayout>
    android.support.v4.widget.NestedScrollView>
android.support.design.widget.CoordinatorLayout>

代码 MainActivity.java

package com.vianet21.nestedscrollview;

import android.support.design.widget.TabLayout;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.View;
import android.widget.LinearLayout;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    private List mData;

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

        initData(1);
        initView();
    }

    private void initData(int pager) {
        mData = new ArrayList<>();
        for (int i = 1; i < 50; i++) {
            mData.add("pager" + pager + " 第" + i + "个item");
        }
        Log.e("*****", mData.toString());
    }

    private void initView() {
        //设置ToolBar
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        toolbar.setTitle("");
        toolbar.setNavigationIcon(R.mipmap.arrow_back);
        setSupportActionBar(toolbar);//替换系统的actionBar

        //设置TabLayout
        TabLayout tabLayout = (TabLayout) findViewById(R.id.tabLayout);
        for (int i = 1; i < 10; i++) {
            tabLayout.addTab(tabLayout.newTab().setText("TAB" + i));
        }
        //TabLayout的切换监听
        tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                initData(tab.getPosition() + 1);
                setScrollViewContent();
            }

            @Override
            public void onTabUnselected(TabLayout.Tab tab) {

            }

            @Override
            public void onTabReselected(TabLayout.Tab tab) {

            }
        });
        setScrollViewContent();
    }

    /**
     * 刷新ScrollView的内容
     */
    private void setScrollViewContent() {
        //NestedScrollView下的LinearLayout
        LinearLayout layout = (LinearLayout) findViewById(R.id.ll_sc_content);
        layout.removeAllViews();
        for (int i = 0; i < mData.size(); i++) {
            View view = View.inflate(MainActivity.this, R.layout.item_layout, null);
            ((TextView) view.findViewById(R.id.tv_info)).setText(mData.get(i));
            //动态添加 子View
            layout.addView(view, i);
        }
    }
}

item_layout.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <TextView
        android:id="@+id/tv_info"
        android:layout_width="match_parent"
        android:layout_height="50dp" />
LinearLayout>

代码网上都有，本文主要记录我遇到的问题：
1，代码编写完了发现没问题，可是运行奔溃，debug发现setSupportActionBar()方法导致，错误日志：

Caused by: java.lang.IllegalStateException: This Activity already has an action bar supplied by the window decor. Do not request Window.FEATURE_SUPPORT_ACTION_BAR and set windowActionBar to false in your theme to use a Toolbar instead.

一般有2种情况：
第一，导包错误 import android.support.v7.widget.Toolbar;；
第二，用了此方法的activity要继承AppCompatActivity(ActionBarActivity也可以)，并且需要修改theme，
AndroidManifest.xml
android:theme="@style/AppTheme.Base">





styles.xml

2，错误日志

这种情况是由于依赖库的版本不一致导致的，把build.gradle中的 v4 v7 和其他依赖库版本改为一致即可：

compile 'com.android.support:appcompat-v7:23.1.1'
compile 'com.android.support:design:23.1.1'