Chương trình Demo cách sử dung Scroll trong android

Scroll được hiểu là thanh cuộn. Khi dữ liệu dài quá màn hình, thì người dùng sẽ sử dụng thanh cuộn để scroll lên hoặc xuống.
Giao diện minh họa:

Đầu tiên ta tạo layout:
activity_main.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout 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" 

 android:paddingLeft="@dimen/activity_horizontal_margin"   

 android:paddingRight="@dimen/activity_horizontal_margin"    

 android:paddingTop="@dimen/activity_vertical_margin"    

 android:paddingBottom="@dimen/activity_vertical_margin" 

 tools:context=".MainActivity">

 <ScrollView  android:id="@+id/scrollView"       

              android:layout_width="wrap_content"       

              android:layout_height="wrap_content">
<LinearLayout          

 android:orientation="vertical"           

 android:layout_width="match_parent"           

 android:layout_height="wrap_content">
           <Button               android:layout_width="wrap_content"               android:layout_height="wrap_content"               android:text="Xin Chào"               ></Button>
           <Button               android:layout_width="wrap_content"               android:layout_height="wrap_content"               android:text="Xin Chào"               ></Button>
           <Button               android:layout_width="wrap_content"               android:layout_height="wrap_content"               android:text="Xin Chào"               ></Button>
           <Button               android:layout_width="wrap_content"               android:layout_height="wrap_content"               android:text="Xin Chào"               ></Button>

           <Button               android:layout_width="wrap_content"               android:layout_height="wrap_content"               android:text="Xin Chào"               ></Button>
           <Button               android:layout_width="wrap_content"               android:layout_height="wrap_content"               android:text="Xin Chào"               ></Button>
           <Button               android:layout_width="wrap_content"               android:layout_height="wrap_content"               android:text="Xin Chào"               ></Button>
           <Button               android:layout_width="wrap_content"               android:layout_height="wrap_content"               android:text="Xin Chào"               ></Button>
           <Button               android:layout_width="wrap_content"               android:layout_height="wrap_content"               android:text="Xin Chào"               ></Button>
           <Button               android:layout_width="wrap_content"               android:layout_height="wrap_content"               android:text="Xin Chào"               ></Button>
           <Button               android:layout_width="wrap_content"               android:layout_height="wrap_content"               android:text="Xin Chào"               ></Button>
           <Button               android:layout_width="wrap_content"               android:layout_height="wrap_content"               android:text="Xin Chào"               ></Button>
       </LinearLayout>
   </ScrollView>
</LinearLayout>

Sau đó:

Xử lý trong class MainActivity.java

package com.example.minhtung.demoscroll;

import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.ViewTreeObserver;
import android.widget.ScrollView;
import android.widget.Scroller;
import android.widget.Toast;

public class MainActivity extends ActionBarActivity implements ViewTreeObserver.OnScrollChangedListener{
    ScrollView sc;
    @Override    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        sc=(ScrollView)findViewById(R.id.scrollView); //Tim id scrollView bên layout        sc.getViewTreeObserver().addOnScrollChangedListener(this); //Lấy ViewTree sau đó add vào sự kiện Scroll change    }
    @Override    public void onScrollChanged() {
        Toast.makeText(MainActivity.this,"bạn đã scroll",Toast.LENGTH_SHORT).show();//xuất ra thông báo    }
}

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