学习日志18
底部导航栏+ViewPager滑动切换页面
1.view简介
一个页面切换的组件，我们可以往里面填充多个View，然后我们可以通过触摸屏幕左右滑动 切换不同的View。
2.案例演示
在project视图中写入几个Java类，与上一个博客使用的方法相同就不显示了。
2.1在activity_mian.xml文件中写入
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="net.nell.fragmentdemo.MainActivity">
<RelativeLayout
android:id="@+id/ly_top_bar"
android:layout_width="match_parent"
android:layout_height="48dp"
android:background="@color/bg_topbar">
<TextView
android:id="@+id/txt_topbar"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_centerInParent="true"
android:gravity="center"
android:text="提醒"
android:textColor="@color/text_topbar"
android:textSize="18sp" />
<View
android:layout_width="match_parent"
android:layout_height="2px"
android:layout_alignParentBottom="true"
android:background="@color/div_white" />
</RelativeLayout>
<RadioGroup
android:id="@+id/rg_tab_bar"
android:layout_width="match_parent"
android:layout_height="56dp"
android:layout_alignParentBottom="true"
android:background="@color/bg_white"
android:orientation="horizontal">
<RadioButton
android:id="@+id/rb_channel"
style="@style/tab_menu_item"
android:drawableTop="@drawable/tab_menu_channel"
android:text="@string/tab_menu_alert" />
<RadioButton
android:id="@+id/rb_message"
style="@style/tab_menu_item"
android:drawableTop="@drawable/tab_menu_message"
android:text="@string/tab_menu_profile" />
<RadioButton
android:id="@+id/rb_better"
style="@style/tab_menu_item"
android:drawableTop="@drawable/tab_menu_better"
android:text="@string/tab_menu_pay" />
<RadioButton
android:id="@+id/rb_setting"
style="@style/tab_menu_item"
android:drawableTop="@drawable/tab_menu_setting"
android:text="@string/tab_menu_setting" />
</RadioGroup>
<View
android:id="@+id/div_tab_bar"
android:layout_width="match_parent"
android:layout_height="2px"
android:layout_above="@id/rg_tab_bar"
android:background="@color/div_white" />
<androidx.viewpager.widget.ViewPager
android:id="@+id/vpager"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_above="@id/div_tab_bar"
android:layout_below="@id/ly_top_bar" />
</RelativeLayout>
2.2创建一个新的类写入代码
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.view.ViewGroup;
public class MyFragmentPagerAdapter extends FragmentPagerAdapter {
private final int PAGER_COUNT = 4;
private MyFragment1 myFragment1 = null;
private MyFragment2 myFragment2 = null;
private MyFragment3 myFragment3 = null;
private MyFragment4 myFragment4 = null;
public MyFragmentPagerAdapter(FragmentManager fm) {
super(fm);
myFragment1 = new MyFragment1();
myFragment2 = new MyFragment2();
myFragment3 = new MyFragment3();
myFragment4 = new MyFragment4();
}
@Override
public int getCount() {
return PAGER_COUNT;
}
@Override
public Object instantiateItem(ViewGroup vg, int position) {
return super.instantiateItem(vg, position);
}
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
System.out.println("position Destory" + position);
super.destroyItem(container, position, object);
}
@Override
public Fragment getItem(int position) {
Fragment fragment = null;
switch (position) {
case MainActivity.PAGE_ONE:
fragment = myFragment1;
break;
case MainActivity.PAGE_TWO:
fragment = myFragment2;
break;
case MainActivity.PAGE_THREE:
fragment = myFragment3;
break;
case MainActivity.PAGE_FOUR:
fragment = myFragment4;
break;
}
return fragment;
}
}
2.3在主方法中写入代码
import android.os.Bundle;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity implements RadioGroup.OnCheckedChangeListener,
ViewPager.OnPageChangeListener {
//UI Objects
private TextView txt_topbar;
private RadioGroup rg_tab_bar;
private RadioButton rb_channel;
private RadioButton rb_message;
private RadioButton rb_better;
private RadioButton rb_setting;
private ViewPager vpager;
private MyFragmentPagerAdapter mAdapter;
//几个代表页面的常量
public static final int PAGE_ONE = 0;
public static final int PAGE_TWO = 1;
public static final int PAGE_THREE = 2;
public static final int PAGE_FOUR = 3;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mAdapter = new MyFragmentPagerAdapter(getSupportFragmentManager());
bindViews();
rb_channel.setChecked(true);
}
private void bindViews() {
txt_topbar = (TextView) findViewById(R.id.txt_topbar);
rg_tab_bar = (RadioGroup) findViewById(R.id.rg_tab_bar);
rb_channel = (RadioButton) findViewById(R.id.rb_channel);
rb_message = (RadioButton) findViewById(R.id.rb_message);
rb_better = (RadioButton) findViewById(R.id.rb_better);
rb_setting = (RadioButton) findViewById(R.id.rb_setting);
rg_tab_bar.setOnCheckedChangeListener(this);
vpager = (ViewPager) findViewById(R.id.vpager);
vpager.setAdapter(mAdapter);
vpager.setCurrentItem(0);
vpager.addOnPageChangeListener(this);
}
@Override
public void onCheckedChanged(RadioGroup group, int checkedId) {
switch (checkedId) {
case R.id.rb_channel:
vpager.setCurrentItem(PAGE_ONE);
break;
case R.id.rb_message:
vpager.setCurrentItem(PAGE_TWO);
break;
case R.id.rb_better:
vpager.setCurrentItem(PAGE_THREE);
break;
case R.id.rb_setting:
vpager.setCurrentItem(PAGE_FOUR);
break;
}
}
//重写ViewPager页面切换的处理方法
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
@Override
public void onPageSelected(int position) {
}
@Override
public void onPageScrollStateChanged(int state) {
//state的状态有三个，0表示什么都没做，1正在滑动，2滑动完毕
if (state == 2) {
switch (vpager.getCurrentItem()) {
case PAGE_ONE:
rb_channel.setChecked(true);
break;
case PAGE_TWO:
rb_message.setChecked(true);
break;
case PAGE_THREE:
rb_better.setChecked(true);
break;
case PAGE_FOUR:
rb_setting.setChecked(true);
break;
}
}
}
}