MainActivity-优快云博客

本文介绍了一个Android应用中实现底部导航栏与视图分页器结合的方法。通过BottomNavigationView和ViewPager组件，文章展示了如何创建切换不同页面的功能，并保持与底部导航项的一致性。代码示例中包含了MainActivity的实现细节，包括FragmentPagerAdapter的使用，以及如何响应导航项选择事件。

package com.example.work1;

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

import com.example.work1.fragment.Fragmentone;
import com.example.work1.fragment.Fragmentthree;
import com.example.work1.fragment.Fragmenttwo;

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

public class MainActivity extends AppCompatActivity {

private TextView mTextMessage;
private ViewPager viewpager;
private List<Fragment>list;

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

    @Override
    public boolean onNavigationItemSelected(@NonNull MenuItem item) {
        switch (item.getItemId()) {
            case R.id.navigation_home:
               viewpager.setCurrentItem(0);
                return true;
            case R.id.navigation_dashboard:
               viewpager.setCurrentItem(1);
                return true;
            case R.id.navigation_notifications:
                viewpager.setCurrentItem(2);
                return true;
        }
        return false;
    }
};

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

    viewpager=findViewById(R.id.viewpager);
    list=new ArrayList<Fragment>();
    Fragmentone fragmentone=new Fragmentone();
    Fragmenttwo fragmenttwo=new Fragmenttwo();
    Fragmentthree fragmentthree=new Fragmentthree();

    list.add(fragmentone);
    list.add(fragmenttwo);
    list.add(fragmentthree);

    viewpager.setAdapter(new FragmentPagerAdapter(getSupportFragmentManager()) {
        @Override
        public Fragment getItem(int i) {

            return list.get(i);
        }

        @Override
        public int getCount() {
            return 3;
        }
    });
    mTextMessage = (TextView) findViewById(R.id.message);
    final BottomNavigationView navigation = (BottomNavigationView) findViewById(R.id.navigation);
    navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);

    viewpager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
        @Override
        public void onPageScrolled(int i, float v, int i1) {

        }

        @Override
        public void onPageSelected(int i) {
            switch (i){
                case 0:
                    navigation.setSelectedItemId(R.id.navigation_home);
                    break;
                case 1:
                    navigation.setSelectedItemId(R.id.navigation_dashboard);
                    break;
                case 2:
                    navigation.setSelectedItemId(R.id.navigation_notifications);
                    break;
            }
        }

        @Override
        public void onPageScrollStateChanged(int i) {

        }
    });
}

}