public class PieChartView extends View {  private Paint mPaint;  private List<PieData>pieDataList;  // 餅狀圖初始繪制角度  private float mStartAngle = 0;  public PieChartView(Context context) {  this(context, null);  }  public PieChartView(Context context, @Nullable AttributeSet attrs) {  super(context, attrs);  init();  }  public void setData(List<PieData> dataList){  if (null == dataList || dataList.size() == 0)  return;  pieDataList = dataList;  invalidate(); //觸發onDraw  }  private void init() {  mPaint = new Paint();  mPaint.setAntiAlias(true);  mPaint.setStyle(Paint.Style.FILL);  mPaint.setStrokeWidth(4);  rectF = new RectF(100f, 100f, 600f, 600f); //正方形背景  }  private RectF rectF;  @Override  protected void onDraw(Canvas canvas) {  super.onDraw(canvas);  if (null == pieDataList || pieDataList.size() == 0)  return;  float currentAngle = mStartAngle;  for (int i = 0;i<pieDataList.size();i++){  PieData pieData = pieDataList.get(i);  mPaint.setColor(pieData.color);  canvas.drawArc(rectF,currentAngle,pieData.angle,true,mPaint); //畫弧  currentAngle += pieData.angle;  }  } } 

int values[] = {30, 30, 40}; //右側的圖的數據，{10, 20, 70} 圖左 List<PieData> pieDataList = new ArrayList<>(); PieData pieData1 = new PieData(); pieData1.percentage = (float) values[0] / 100; pieData1.angle = pieData1.percentage * 360; pieData1.color = Color.RED; pieDataList.add(pieData1); PieData pieData2 = new PieData(); pieData2.percentage = (float) values[1] / 100; pieData2.angle = pieData2.percentage * 360; pieData2.color = Color.GREEN; pieDataList.add(pieData2); PieData pieData3 = new PieData(); pieData3.percentage = (float) values[2] / 100; pieData3.angle = pieData3.percentage * 360; pieData3.color = Color.YELLOW; pieDataList.add(pieData3);  PieChartView pieChartView = new PieChartView(mContext); pieChartView.setData(pieDataList); addView(pieChartView);