Java 浮子式铸造isn'；t工作正常，始终计算为0.0

代码：

我在谷歌上搜索了一下，还没有找到答案。好吧，我输入的是正确的，但它的计算结果一直是0.0。在计算过程中，我甚至尝试将

360

、

percentage

和

100

类型转换为float，但仍然不起作用

EDIT1: 完整代码：

double percentage = 0.7711627906976745;
mSweepAngle = (float)(360*(percentage/(double)100));

---

请注意，已成功地从另一个活动传递了百分比，当前正在传递0.7711627906976745。

您正在从构造函数调用

init

，而执行此计算的是

init

。因此，无论您使用什么机制来设置

百分比

，在计算完成之前都不会发生

---

我郑重建议学习使用调试器。单步执行代码会立即告诉您发生了什么。

当我运行此程序时（后面是

System.out.println（mSweepAngle）；

），它给了我

2.776186

。您确定除了此代码之外没有其他问题吗？事实上，您不需要所有这些铸件。由于

percentage

已经是

double

，它的除法和乘法返回

double

值（编译器将

int

转换为

double

）。您提到的问题是，当您对整数进行除法时（v.g.

4/10

返回

0

），是否可能有一个名为

msweapangle

的字段，以及一个名为

msweapangle

的局部变量来屏蔽它？或者你在一个物体上做这个计算，然后在另一个物体上检查值？像这样的？请给我们看你所有的代码，不仅仅是这两行-这两行都很好。显示a。请检查我的编辑，我添加了完整的代码。

package se.kiendys.petrus.da171a.uppg3.budgetapp;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.RectF;
import android.graphics.Paint.Style;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;

public class PieChartView extends View {

    private Paint piechartItem1Paint;
    private Paint piechartItem2Paint;
    private Paint piechartBorderPaint;
    private Paint infoBorderPaint;
    private Paint infoBackgroundPaint;
    private Paint infoTextPaint;
    private RectF oval;

    private int mWidth;
    private int mHeight;
    private int mMarginLeft;
    private int mMarginTop;
    private float mStartAngle;
    private float mSweepAngle;

    private double percentage;

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

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

    public void init() {
        piechartItem1Paint = new Paint();                   // the piechart items color
        piechartItem2Paint = new Paint();                   // the piechart items color
        piechartBorderPaint = new Paint();                  // the piechart border color
        infoTextPaint = new Paint();                        // the info text color
        infoBackgroundPaint = new Paint();                  // the info background color
        infoBorderPaint = new Paint();                      // the info border color

        mWidth = 200;       // circle width
        mHeight = 200;      // circle height
        mMarginLeft = 10;   // circle and info margin
        mMarginTop = 10;    // circle and info margin
        mStartAngle = 0;    // the starting angle of the arc, begins at the rightmost part of the circle (an angle of 0 degrees correspond to the geometric angle of 0 degrees, or 3 o'clock on a watch)
                            // and through incrementation moves clockwise, the units are degrees

        oval = new RectF(mMarginLeft, mMarginTop, mWidth, mHeight); // sets the shape and size (boundaries) of the drawn circle

        piechartItem1Paint.setAntiAlias(true);
        piechartItem1Paint.setStyle(Style.FILL);
        piechartItem1Paint.setStrokeWidth(0.5f);
        piechartItem2Paint.setAntiAlias(true);
        piechartItem2Paint.setStyle(Style.FILL);
        piechartItem2Paint.setStrokeWidth(0.5f);

        piechartItem1Paint.setColor(0xCCFEFEFE);    // blue color
        piechartItem2Paint.setColor(0xCC343434);    // green color

//      double temp = (360*((double)percentage/(double)100));
//      Log.d(BudgetConstants.DEBUG_TAG, "temp: "+temp);
//      mSweepAngle = (float)temp;
//      Log.d(BudgetConstants.DEBUG_TAG, "init mSweepAngle: "+mSweepAngle);
//      mSweepAngle = (float)(360*(percentage/(double)100));
//      mSweepAngle = (float)(percentage/100.0*360);
        Log.d(BudgetConstants.DEBUG_TAG, "init mSweepAngle: "+mSweepAngle);
    }

    public void setDistributionPercentage(double percentage) {
        this.percentage = percentage;
        Log.d(BudgetConstants.DEBUG_TAG, "percentage: "+percentage);
    }

    protected void onDraw(Canvas canvas) {
        Log.d(BudgetConstants.DEBUG_TAG, "onDraw fired!");

        canvas.drawArc(oval, mStartAngle, mSweepAngle, true, piechartItem1Paint);
        Log.d(BudgetConstants.DEBUG_TAG, "startAngle1: "+mStartAngle+", sweepAngle1: "+mSweepAngle);
        canvas.drawArc(oval, mSweepAngle, (360-mSweepAngle), true, piechartItem2Paint);
        Log.d(BudgetConstants.DEBUG_TAG, "startAngle2: "+mSweepAngle+", sweepAngle2: "+(360-mSweepAngle));
    }

}