Android seekbar实现可拖动进度条

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:orientation="vertical">
 
 <SeekBar
   android:id="@+id/seekBar"
   android:layout_width="match_parent"
   android:layout_height="wrap_content"
   android:max="100"
   android:progress="50" />
 
 <TextView
   android:id="@+id/tv1"
   android:layout_width="match_parent"
   android:layout_height="wrap_content"
    />
 
 <TextView
   android:id="@+id/tv2"
   android:layout_width="match_parent"
   android:layout_height="wrap_content" />
 
</LinearLayout>

package com.example.lenovo.seekbar;
 
import android.app.Activity;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.SeekBar;
import android.widget.TextView;
 
public class MainActivity extends Activity implements SeekBar.OnSeekBarChangeListener {
 
  private SeekBar seekBar;
  private TextView tv1;
  private TextView tv2;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    tv1=findViewById(R.id.tv1);
    tv2=findViewById(R.id.tv2);
    seekBar=findViewById(R.id.seekBar);
    //设置监听器 监听数值改变情况
    seekBar.setOnSeekBarChangeListener(this);
  }
  //数值改变
  @Override
  public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
    tv1.setText("正在拖动");
    tv2.setText("当前数值："+progress);
  }
  //开始拖动
  @Override
  public void onStartTrackingTouch(SeekBar seekBar) {
    tv1.setText("开始拖动");
  }
  //停止拖动
  @Override
  public void onStopTrackingTouch(SeekBar seekBar) {
    tv1.setText("停止拖动");
  }
}