Android 中SeekBar拖动条控件的基本用法

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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=".SeekBarActivity"
    android:orientation="vertical"
    >
    <SeekBar
        android:id="@+id/seek_bar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:max="100"
        android:thumb="@drawable/seekbar_point"
        />
    <TextView
        android:id="@+id/tv_seek_bar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="当前进度为"
        android:gravity="center"
        android:textSize="17sp"
        android:textColor="@color/black"
        />
</LinearLayout>

public class SeekBarActivity extends AppCompatActivity implements SeekBar.OnSeekBarChangeListener {
    private SeekBar seek_bar;
    private TextView tv_seek_bar;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_seek_bar);
        seek_bar = findViewById(R.id.seek_bar);
        tv_seek_bar = findViewById(R.id.tv_seek_bar);
        //给拖动条设置拖动变更监听器
        seek_bar.setOnSeekBarChangeListener(this);
        //设置拖动条的当前进度
        seek_bar.setProgress(50);
    }
    //在进度变更时触发。第三个参数为true表示用户拖动，为false表示代码设置进度
    @Override
    public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
        String desc = "当前进度为:" + seekBar.getProgress() + ",最大进度为" + seekBar.getMax();
        tv_seek_bar.setText(desc);
    }
    //在开始拖动进度时触发
    @Override
    public void onStartTrackingTouch(SeekBar seekBar) {
    }
    //在停止拖动进度时触发
    @Override
    public void onStopTrackingTouch(SeekBar seekBar) {
    }
}