java - 转换计算器，结果有问题..随机答案不正确？

Question

好吧，我对整体成品有疑问，我对此很陌生，所以我无法发现哪里出了问题。我输入我的转换类型，例如:1(英寸-厘米)说我想知道 5 英寸是多少厘米，结果会是:12.7 厘米 = 55.0 ？对我来说，为什么这样做毫无意义，任何帮助都会很棒!

switch(Integer.parseInt(jTextField1.getText())){  
case 1:
InchesToCm();
break;
case 2:
CmToFeet();
break;
case 3:
MetresToYards();
break;
case 4:
KmToMetres();
break;
default:
jLabel8.setText("Error, try again");
break;

}








}                                        


private void InchesToCm() {
 double inches, centimetres;   //identify variables
String messageOut;

inches = Double.parseDouble(jTextField2.getText());          //get the text
centimetres = (inches*2.54);                                 //preform   
messageOut = centimetres + "cm = " + Math.round(inches) + inches;    //msg
jLabel8.setText(messageOut);
 } 
private void CmToFeet() {
double feet, centimetres;
String messageOut;

feet = Double.parseDouble(jTextField2.getText());
centimetres = (feet*30);
messageOut = centimetres + "cm = " + Math.round(feet) + feet;
jLabel8.setText(messageOut);

}
private void MetresToYards() {
double metres, yards;
String messageOut;

yards = Double.parseDouble(jTextField2.getText());
metres = (yards*0.91);
messageOut = metres + "m = " + Math.round(yards) + yards;
jLabel8.setText(messageOut);
}
private void KmToMetres() {
double miles, kilometres;
String messageOut;

miles = Double.parseDouble(jTextField2.getText());
kilometres = (miles*1.6);
messageOut = kilometres + "km = " + Math.round(miles) + miles;
jLabel8.setText(messageOut);
}

Answer 1

您连续两次打印 inches 变量，这让您感到困惑。 Math.round 返回值负责 5 以及 inches 本身的打印(double)负责 5.0。连接起来，它显示为 55.0。我怀疑您想要打印字符串 “英寸”:

messageOut = centimetres + "cm = " + Math.round(inches) + " inches";

应对其他方法进行类似的更改。