Android java:绘制正弦波形图像

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.View;

public class SineWaveView extends View {
    private Paint paint;
    private float amplitude; // 振幅
    private float frequency; // 频率
    private float phase; // 相位

    public SineWaveView(Context context) {
        super(context);
        init();
    }

    public SineWaveView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    private void init() {
        paint = new Paint();
        paint.setColor(Color.BLUE);
        paint.setStrokeWidth(2);
        paint.setStyle(Paint.Style.STROKE);
        amplitude = 100;
        frequency = 0.01f;
        phase = 0;
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        int width = getWidth();
        int height = getHeight();
        float midY = height / 2;

        float startX = 0;
        float startY = midY;

        float endX;
        float endY;

        for (float x = startX; x < width; x += 1) {
            endX = x;
            endY = (float) (midY + amplitude * Math.sin(frequency * x + phase));
            canvas.drawLine(startX, startY, endX, endY, paint);
            startX = endX;
            startY = endY;
        }
    }
}

public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        SineWaveView sineWaveView = findViewById(R.id.sineWaveView);
    }
}

<com.example.myapplication.SineWaveView
    android:id="@+id/sineWaveView"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />