[英]java logic issue in method
當我嘗試運行此代碼時,它將不斷返回錯誤的值,並且我無法弄清楚哪里出了問題。 我將10添加到catUp后,它可以正確打印,但是當我檢查該值是否大於199時,由於某種原因它會通過該if語句。 同樣,當我在upCategory方法的末尾將其打印出來時,它的值為1,但是當我在主窗口中打印時,它的值為3。
public void upCategory()
{
double catUp = radioXM.getCurrentStaion();
catUp += 10;
System.out.println(catUp);
if (catUp > 199.0);
{
catUp = 1;
radioXM.setCurrentStation(catUp);
System.out.println(catUp);
}
radioXM.setCurrentStation(catUp);
System.out.println(catUp);
}
public static void main (String [] args) {
AutoRadioSystem c = new AutoRadioSystem();
c.selectRadio();
double b = c.getCurrentStation();
System.out.println(b);
// this changes the radio to XM
c.selectRadio();
double d = c.getCurrentStation();
System.out.println(d);
//this is suppose to change the station up by 10 but gives incorrect value
c.upCategory();
double f = c.getCurrentStation();
System.out.println(f);
}
附帶的其他代碼...
public abstract class Radio
{
double currentStation;
RadioSelectionBar radioSelectionBar;
public Radio()
{
this.currentStation = getMin_Station();
}
public abstract double getMax_Station();
public abstract double getMin_Station();
public abstract double getIncrement();
public void up()
{
}
public void down()
{
}
public double getCurrentStaion()
{
return this.currentStation;
}
public void setCurrentStation(double freq)
{
currentStation += freq;
}
public void setStation(int buttonNumber, double station)
{
}
public double getStation(int buttonNumber)
{
return 0.0;
}
public String toString()
{
String message = ("" + currentStation);
return message;
}
public boolean equals (Object o)
{
if (o == null)
return false;
if (! (o instanceof Radio))
return false;
Radio other = (Radio) o;
return this.currentStation == other.currentStation;
}
public class XMRadio extends Radio
{
private static final double Max_Station = 199;
private static final double Min_Station = 1;
private static final double Increment = 1;
public XMRadio()
{
}
public double getMax_Station()
{
return this.Max_Station;
}
public double getMin_Station()
{
return this.Min_Station;
}
public double getIncrement()
{
return this.Increment;
}
public String toString()
{
String message = ("XM "+ currentStation );
return message;
}
}
這行是問題所在:
if (catUp > 199.0);
Java的把分號作為機構的if
語句,然后在下面的括號中的塊if
成為一個正常的塊,並始終執行。
要將大括號中的塊附加到if
語句,請刪除分號:
if (catUp > 199.0)
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