BottomNavigationView+ViewPager+Fragment

package com.shop.pet;

import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.design.widget.BottomNavigationView;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;


public class MainActivity extends AppCompatActivity {

    private TextView mTextMessage;
    private ViewPager mViewPager;
    private MenuItem mMenuItem;

    private BottomNavigationView navigation;


    private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
            = new BottomNavigationView.OnNavigationItemSelectedListener() {

        @Override
        public boolean onNavigationItemSelected(@NonNull MenuItem item) {
            switch (item.getItemId()) {
                case R.id.navigation_home:
                    mViewPager.setCurrentItem(0);
                    return true;
                case R.id.navigation_pet:
                    mViewPager.setCurrentItem(1);
                    return true;
                case R.id.navigation_find:
                    mViewPager.setCurrentItem(2);
                    return true;
                case R.id.navigation_message:
                    mViewPager.setCurrentItem(3);
                    return true;
                case R.id.navigation_my:
                    mViewPager.setCurrentItem(4);
                    return true;
            }
            return false;
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mViewPager = (ViewPager) findViewById(R.id.viewpager);

        navigation = (BottomNavigationView) findViewById(R.id.navigation);
        navigation.setLabelVisibilityMode(1);
        navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);

        setupViewPager(mViewPager);

    }

    private void setupViewPager(ViewPager viewPager) {
        ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());

        adapter.addFragment(R.id.f_home, BaseFragment.newInstance(0));
        adapter.addFragment(R.id.f_pet, BaseFragment.newInstance(1));
        adapter.addFragment(R.id.f_find, BaseFragment.newInstance(2));
        adapter.addFragment(R.id.f_message, BaseFragment.newInstance(3));
        adapter.addFragment(R.id.f_my, BaseFragment.newInstance(4));

        viewPager.setAdapter(adapter);


        viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

            }

            @Override
            public void onPageSelected(int position) {
                if (mMenuItem != null) {
                    mMenuItem.setChecked(false);
                } else {
                    navigation.getMenu().getItem(0).setChecked(false);
                }
                mMenuItem = navigation.getMenu().getItem(position);
                mMenuItem.setChecked(true);
            }

            @Override
            public void onPageScrollStateChanged(int state) {
            }
        });

    }

}

一些网友可能会遇到BottomNavigationView的Item项超过3时，不能完全显示文字，从代码中可以看到如下部分

    private boolean isShifting(int labelVisibilityMode, int childCount) {
        return labelVisibilityMode == -1 ? childCount > 3 : labelVisibilityMode == 0;
    }

所以代码中将labelVisibilityMode设置掉即可。