内容纲要

底部导航栏切换Fragment进行显示

创建Fragment对象

通常会有多个Fragment用于切换

用Fragment[] fragments保存为集合

private FrameLayout frame_home;

private Fragment[] fragments;

private HomeFragment homeFragment;

private int lastfragment = 0;

显示Fragment对象

加载Fragment视图

private void initView() {

//加载Fragment

homeFragment = new HomeFragment();

//Fragments集合

fragments = new Fragment[]{homeFragment};

//加载FrameLayout布局

frame_home = (FrameLayout) findViewById(R.id.frame_home);

//设置fragment到布局

getSupportFragmentManager().beginTransaction().replace(R.id.frame_home,homeFragment).show(homeFragment).commit();

}

切换Fragment

管理多个Fragment并切换

切换到指定Fragment

//切换fragment

private void switchFragment(int lastfragment, int index) {

FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();

//隐藏上个Fragment

transaction.hide(fragments[lastfragment]);

if (!fragments[index].isAdded()) {

transaction.add(R.id.frame_home, fragments[index]);

}

transaction.show(fragments[index]).commitAllowingStateLoss();

}

底部导航栏点击事件监听器

//底部导航栏点击响应事件

private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener

= new BottomNavigationView.OnNavigationItemSelectedListener() {

@Override

public boolean onNavigationItemSelected(@NonNull MenuItem item) {

switch (item.getItemId()) {

case R.id.nav_home:

if (lastfragment != 0) {

switchFragment(lastfragment, 0);

lastfragment = 0;

}

ToastUtil.showToast(getApplicationContext(), "点击了nav_home");

return true;

case R.id.nav_zoom:

// if (lastfragment != 1) {

// switchFragment(lastfragment, 1);

// lastfragment = 1;

// }

ToastUtil.showToast(getApplicationContext(), "点击了nav_zoom");

return true;

case R.id.nav_user:

ToastUtil.showToast(getApplicationContext(), "点击了nav_user");

return true;

default:

break;

}

return false;

}

};