Android实现底部菜单的跳转--BottomNavigationView

效果图：

1.新建一个一个Activity

2.在分别新建三个Activity，放置底部按钮对应的界面

Sub1Activity.java如下：其余Activity.java文件对照于此

package com.huilian.manager;

import android.support.annotation.Nullable;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.TextView;

public class Sub1Activity extends Fragment {
    private TextView textView;
    private Button button;
    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        //不同的Activ