Android界面编程之SeekBar/RatingBar

SeekBar：
SeekBar是进度条。我们使用进度条时，可以使用系统默认的进度条；也可以自定义进度条的图片和滑块图片等。
RatingBar
评分条，与拖动条类似
用星星表示进
度
示例：
  

<ImageView
        android:id="@+id/imageView2"
        android:layout_width="300dp"
        android:layout_height="300dp"
        app:srcCompat="@drawable/img1"
        tools:layout_editor_absoluteY="0dp"
        tools:layout_editor_absoluteX="8dp" />

    <SeekBar
        android:id="@+id/seekBar"
        android:layout_width="368dp"
        android:layout_height="wrap_content"
        tools:layout_editor_absoluteX="8dp"
        android:max="255"
        android:progress="255"
        app:layout_constraintTop_toBottomOf="@+id/imageView2"/>

    <RatingBar
        android:id="@+id/ratingBar"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        tools:layout_editor_absoluteX="0dp"
        android:numStars="5"
        android:stepSize="0.5"
        android:rating="5"
        app:layout_constraintTop_toBottomOf="@+id/seekBar"/>
    //setpSize是最少的单位是多少
    //numStarts是星星数量

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        final ImageView imageView = (ImageView)findViewById(R.id.imageView2);
        final SeekBar seekBar = (SeekBar)findViewById(R.id.seekBar);
        final RatingBar ratingBar = (RatingBar)findViewById(R.id.ratingBar);
        seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
            @Override
            public void onProgressChanged(SeekBar seekBar, int i, boolean b) {
                imageView.setImageAlpha(i);
                ratingBar.setRating(i*5.0f/255);
            }

            @Override
            public void onStartTrackingTouch(SeekBar seekBar) {

            }

            @Override
            public void onStopTrackingTouch(SeekBar seekBar) {

            }
        });
        ratingBar.setOnRatingBarChangeListener(new RatingBar.OnRatingBarChangeListener() {
            @Override
            public void onRatingChanged(RatingBar ratingBar, float v, boolean b) {
                imageView.setImageAlpha((int)v*255/5);
                seekBar.setProgress((int)v*255/5);
//设置SeekBar的值
            }
        });

    }
}