Android拖动条的实现代码

<?xml version="1.0" encoding="utf-8"?> 
<android.support.constraint.constraintlayout xmlns:android="http://schemas.android.com/apk/res/android" 
 xmlns:app="http://schemas.android.com/apk/res-auto" 
 xmlns:tools="http://schemas.android.com/tools" 
 android:layout_width="match_parent" 
 android:layout_height="match_parent" 
 tools:context="com.amy.seekbartest.mainactivity"> 
 
 <textview 
  android:id="@+id/textview1" 
  android:layout_width="wrap_content" 
  android:layout_height="wrap_content" 
  android:text="当前值：50" 
  android:textsize="16sp" 
  android:paddingtop="40dp" 
  android:paddingleft="15dp" 
  tools:layout_editor_absolutey="0dp" 
  tools:layout_editor_absolutex="0dp" /> 
 <!-- 拖动条 --> 
 <seekbar 
  android:id="@+id/seekbar1" 
  android:layout_height="wrap_content" 
  android:max="100" 
  android:layout_width="match_parent" 
  android:progress="50" 
  android:paddingtop="10dp" 
  tools:layout_editor_absolutey="0dp" 
  tools:layout_editor_absolutex="32dp" /> 
</android.support.constraint.constraintlayout> 

package com.amy.seekbartest; 
 
import android.support.v7.app.appcompatactivity; 
import android.os.bundle; 
import android.view.view; 
import android.widget.seekbar; 
import android.widget.textview; 
import android.widget.toast; 
 
public class mainactivity extends appcompatactivity { 
 
 private seekbar seekbar;//拖动条 
 @override 
 protected void oncreate(bundle savedinstancestate) { 
  super.oncreate(savedinstancestate); 
  setcontentview(r.layout.activity_main); 
  final textview result = (textview) findviewbyid(r.id.textview1); 
  seekbar = (seekbar) findviewbyid(r.id.seekbar1); 
  seekbar.setonseekbarchangelistener(new seekbar.onseekbarchangelistener() { 
   @override 
   public void onprogresschanged(seekbar seekbar, int progress, boolean fromuser) { 
    result.settext("当前值："+progress); 
   } 
 
   @override 
   public void onstarttrackingtouch(seekbar seekbar) { 
    toast.maketext(mainactivity.this,"开始滑动",toast.length_short).show(); 
   } 
 
   @override 
   public void onstoptrackingtouch(seekbar seekbar) { 
    toast.maketext(mainactivity.this,"结束滑动",toast.length_short).show(); 
   } 
  }); 
 } 
}