Giới thiệu
Bài viết này minh họa cách phát hiện khi người dùng cuộn đến đầu hoặc cuối của ScrollView trong Android.
Các bước thực hiện
Bước 1: Tạo dự án mới
Mở Android Studio, chọn File → New Project và điền đầy đủ thông tin để tạo dự án mới.
Bước 2: Thiết kế giao diện (res/layout/activity_main.xml)
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="https://schemas.android.com/apk/res/android"
xmlns:tools="https://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<ScrollView
android:id="@+id/scrollView"
android:layout_width="match_parent"
android:layout_height="match_parent">
<WebView
android:id="@+id/webView"
android:layout_width="match_parent"
android:layout_height="wrap_content">
</WebView>
</ScrollView>
</RelativeLayout>
Bước 3: Viết code xử lý (src/MainActivity.java)
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewTreeObserver;
import android.webkit.WebView;
import android.widget.ScrollView;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity implements View.OnTouchListener, ViewTreeObserver.OnScrollChangedListener {
ScrollView scrollView;
WebView webView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
scrollView = findViewById(R.id.scrollView);
webView = findViewById(R.id.webView);
scrollView.setOnTouchListener(this);
scrollView.getViewTreeObserver().addOnScrollChangedListener(this);
webView.loadData(getResources().getString(R.string.sample_data), "text/html", null);
}
public void onScrollChanged() {
View view = scrollView.getChildAt(scrollView.getChildCount() - 1);
int topDetector = scrollView.getScrollY();
int bottomDetector = view.getBottom() - (scrollView.getHeight() + scrollView.getScrollY());
if (bottomDetector == 0) {
Toast.makeText(getBaseContext(), "Đã cuộn đến cuối ScrollView", Toast.LENGTH_SHORT).show();
}
if (topDetector <= 0) {
Toast.makeText(getBaseContext(), "Đã cuộn đến đầu ScrollView", Toast.LENGTH_SHORT).show();
}
}
@Override
public boolean onTouch(View v, MotionEvent event) {
return false;
}
}
Bước 4: Thêm nội dung HTML (res/values/strings.xml)
<resources>
<string name="app_name">Sample</string>
<string name="sample_data">
<![CDATA[<html>]]>
<![CDATA[<style>]]>
p.small {
line-height: 1.5;
font-size: 12px;
}
<![CDATA[</style>]]>
<![CDATA[<body><p align="justify" class="small">]]>
Chupa chups carrot cake pastry cupcake caramels sugar plum chocolate cupcake tootsie roll.
Cupcake chocolate donut caramels sesame snaps brownie cake halvah.
Sesame snaps sesame snaps gummies candy carrot cake.
Fruitcake bonbon liquorice topping biscuit candy canes fruitcake marzipan cake.
Tart tootsie roll tart gummi bears apple pie danish powder pastry gummies.
Tiramisu sesame snaps icing pudding. Marzipan sweet roll cookie marshmallow.
Tiramisu bear claw bear claw sesame snaps pie marzipan.
Icing candy candy canes danish. Tart lollipop jujubes cake soufflé.
Cheesecake bear claw marshmallow chocolate cake donut sweet.
Tootsie roll topping chocolate bar cupcake cake oat cake oat cake bonbon cotton candy.
Jelly-o croissant dragée lemon drops chocolate bar. Gingerbread cotton candy oat cake marshmallow.
<![CDATA[<br><br>]]>
Lemon drops carrot cake wafer jelly cheesecake chocolate cake gingerbread.
Dessert cookie oat cake pie. Liquorice liquorice dragée lollipop danish jujubes pudding carrot cake.
Jelly beans cotton candy sweet caramels gummies pastry. Wafer wafer muffin sweet roll.
Chocolate topping gummi bears gummies. Oat cake bonbon brownie chocolate bar.
Tart tart gingerbread chupa chups chocolate bar gummies.
<![CDATA[<br><br>]]>
Lemon drops muffin bear claw cake gingerbread apple pie lollipop cheesecake.
Powder bear claw marshmallow. Tootsie roll gummi bears wafer brownie.
Sesame snaps soufflé bear claw chocolate danish candy.
Wafer oat cake ice cream pastry cake muffin toffee tootsie roll. Cake oat cake marshmallow.
Gummi bears gingerbread cake danish muffin marzipan donut cotton candy.
Ice cream topping cake candy gummi bears brownie. Marshmallow chocolate icing candy canes topping.
Pastry gummies powder sesame snaps sugar plum sugar plum.
Lemon drops gummies gummi bears tootsie roll powder jelly-o jelly-o.
Lollipop jujubes sweet brownie croissant soufflé chupa chups bear claw.
Sugar plum sugar plum lollipop croissant lemon drops sweet jujubes soufflé sweet roll.
<![CDATA[<br><br>]]>
Liquorice jelly-o candy lollipop croissant sweet icing brownie biscuit.
Wafer dessert cake marzipan gummies jujubes bonbon tootsie roll ice cream.
Chocolate bar bear claw candy canes lemon drops jelly apple pie cotton candy jujubes.
Donut toffee candy canes dragée cake toffee. Icing cookie biscuit cheesecake dragée.
Gummi bears tiramisu sesame snaps muffin halvah. Sweet jujubes chocolate cake muffin pie bonbon cupcake.
Pastry jujubes pastry fruitcake. Jelly beans dessert gingerbread cupcake gingerbread marshmallow carrot cake.
Macaroon carrot cake candy canes jelly powder. Soufflé macaroon liquorice candy canes lollipop.
Marzipan fruitcake fruitcake gummi bears gummies chocolate cake. Jelly sesame snaps topping sweet.
<![CDATA[<br><br>]]>
Chupa chups macaroon muffin. Topping jujubes biscuit tart jujubes pudding.
Brownie oat cake cookie. Lemon drops pudding tiramisu dessert marzipan.
Danish cake candy canes bonbon. Gummi bears carrot cake apple pie lollipop.
Tart candy canes chocolate cake lemon drops carrot cake topping cheesecake apple pie cake.
Bear claw pudding macaroon croissant halvah caramels.
Danish cake pastry sugar plum lollipop ice cream gummi bears gummi bears sugar plum.
Chocolate macaroon tootsie roll. Halvah tootsie roll sweet roll powder gummi bears chocolate cake.
Sugar plum gingerbread brownie. Wafer chocolate cake bonbon ice cream biscuit dragée tiramisu croissant apple pie.
<![CDATA[</p></body></html>]]>
</string>
</resources>
Bước 5: Cấu hình Manifest (androidManifest.xml)
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="https://schemas.android.com/apk/res/android"
package="app.com.sample">
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
Chạy ứng dụng
Kết nối thiết bị Android thực với máy tính. Trong Android Studio, mở file activity và nhấn biểu tượng Run trên thanh công cụ. Chọn thiết bị di động của bạn và kiểm tra màn hình hiển thị.
