ViewPager自带点击变色，图片

最新推荐文章于 2020-02-17 21:14:42 发布

qq_43559002

最新推荐文章于 2020-02-17 21:14:42 发布

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本文链接：https://blog.youkuaiyun.com/qq_43559002/article/details/85337729

本文详细介绍了一款基于Android的主界面设计与实现过程，包括使用BottomNavigationView进行底部导航、ViewPager实现滑动切换不同Fragment的功能，以及如何通过FragmentPagerAdapter来管理多个Fragment。文章还讲解了如何设置ViewPager的OffscreenPageLimit以避免每次切换时重新创建Fragment，提高应用性能。

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import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
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.v4.widget.DrawerLayout;
import android.support.v7.app.AppCompatActivity;
import android.view.MenuItem;
import android.view.View;
import android.widget.TextView;
import android.widget.Toast;

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

import jiaoyibo.bawei.com.jiaoyibo20190109.base.BaseActivity;
import jiaoyibo.bawei.com.jiaoyibo20190109.fragment.FragmentOne;
import jiaoyibo.bawei.com.jiaoyibo20190109.fragment.FragmentThree;
import jiaoyibo.bawei.com.jiaoyibo20190109.fragment.FragmentTwo;

public class MainActivity extends BaseActivity implements View.OnClickListener {

    private TextView mTextMessage;
    //获取布局的集合
    private List<Fragment> list = new ArrayList<>();
    //自带的点击跳转页面
    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;
        }
    };
    private BottomNavigationView navigation;
    private ViewPager viewPager;

    @Override
    protected void initData() {
        //添加布局
        list.add(new FragmentOne());
        list.add(new FragmentTwo());
        list.add(new FragmentThree());
        //viewPager适配
        viewPager.setAdapter(new FragmentPagerAdapter(getSupportFragmentManager()) {
            @Override
            public Fragment getItem(int i) {
                return list.get(i);
            }

            @Override
            public int getCount() {
                return list.size();
            }
        });
        /**
         * viewpager每次切换的时候， 会重新创建当前界面及左右界面三个界面，
         * 每次切换都要重新oncreate,
         * 所以只要设置viewPager setOffscreenPageLimit即可避免这个问题
         */
        viewPager.setOffscreenPageLimit(list.size());
        //设置viewPager监听
        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) {

            }
        });
    }

    @Override
    protected void initView() {
        viewPager = findViewById(R.id.viewPager);
        mTextMessage = (TextView) findViewById(R.id.message);
        navigation = (BottomNavigationView) findViewById(R.id.navigation);
  navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
    }

    @Override
    protected int getLayoutId() {
        return R.layout.activity_main;
    }
}