java 键入将数字转换为双倍
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Type casting a Number to double
提问by Vishal Kinjavdekar
I am trying to compute few calculations for my project and I get following java.lang.ClassCastExceptionfor
y2= (double) molWt[x];
我试图计算少量计算为我的项目，我获得以下java.lang.ClassCastException的
y2= (double) molWt[x];
molWtand distare two array of type Number and doublerespectively.
molWt和dist分别是 Number 和 类型的两个数组 double。
java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.Double
java.lang.ClassCastException: java.lang.Integer 不能转换为 java.lang.Double
public Double calcData(Number[] molWt, Double[] dist, String unk) {
Double y2,y1, newY = null;
Double x1,x2;
Double unkn = Double.parseDouble(unk.toString());
Double prev=0d;
Double slope;
for (int x = 0; x < dist.length; x++)
if (unkn > prev && unkn < dist[x]) {
y2 = (double) molWt[x];
y1 = (double) molWt[x - 1];
x2 = dist[x];
x1 = dist[x - 1];
slope = ((y2 - y1) / (x2 - x1));
newY = slope * (unkn - x1) + y1;
} else {
prev = dist[x];
}
return newY;
}
回答by Darth Android
Use Number.doubleValue():
y2 = molWt[x].doubleValue();
instead of trying to cast. Numbercannot be cast to a primitive double.
而不是尝试投射。Number不能强制转换为原始double.
回答by metin
you can use java.lang.Number.doubleValue() method to cast a number to a double object.
您可以使用 java.lang.Number.doubleValue() 方法将数字转换为双精度对象。
y2= molWt[x].doubleValue()
y2= molWt[x].doubleValue()
