如何在android的画布上绘制折线？

public class LineChartView extends View {
    private Paint linePaint;
    private Path linePath;

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

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

    private void init() {
        linePaint = new Paint();
        linePaint.setColor(Color.RED);
        linePaint.setStrokeWidth(5);
        linePaint.setStyle(Paint.Style.STROKE);

        linePath = new Path();
    }

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

        int startX = 100;
        int startY = 500;
        int endX = 800;
        int endY = 200;

        linePath.moveTo(startX, startY);
        linePath.lineTo(endX, endY);

        canvas.drawPath(linePath, linePaint);
    }
}

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

        LinearLayout container = findViewById(R.id.container);
        LineChartView lineChartView = new LineChartView(this);
        container.addView(lineChartView);
    }
}