为啥这是一个遥不可及的声明？ [关闭]
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【中文标题】为啥这是一个遥不可及的声明？ [关闭]【英文标题】：Why is this an unreachable statement? [closed]为什么这是一个遥不可及的声明？ [关闭] 【发布时间】：2013-01-23 23:17:29 【问题描述】：在此代码的底部，我收到“无法访问的语句”错误。我已经尝试了一些事情，但无法弄清楚为什么会这样。错误在代码的底部（我已经用 // 注释了错误所在的位置）请帮助我指出正确的方向，我被难住了！
/**
* Describes a certain model.
*
* @author (Joshua Baker)
* @version (1.0)
*/
public class Model
public static final int IN_PER_FOOT = 12;
public static final int BASE_RATE = 60;
public static final int TALL_INCHES = 67;
public static final double THIN_POUNDS = 140.0;
public static final int TALL_THIN_BONUS = 5;
public static final int TRAVEL_BONUS = 4;
public static final int SMOKER_DEDUCTION = 10;
private String firstName;
private String lastName;
private int heightInInches;
private double weightInPounds;
private boolean travel;
private boolean smokes;
private String newHeight;
private int perHourRate;
/**
* Default constructor
*/
public Model()
setFirstName ("");
setLastName ("");
setHeightInInches (0);
setWeightInPounds (0.0);
setTravel (false);
setSmokes (false);
/**
*
*/
public Model (String whatIsFirstName, String whatIsLastName, int whatIsHeight, double whatIsWeight,
boolean canTravel, boolean smoker)
setFirstName (whatIsFirstName);
setLastName (whatIsLastName);
setHeightInInches (whatIsHeight);
setWeightInPounds (whatIsWeight);
setTravel (canTravel);
setSmokes (smoker);
/**
*@return first name
*/
public String getFirstName()
return firstName;
/**
*@return last name
*/
public String getLastName()
return lastName;
/**
*@return height in inches
*/
public int getHeightInInches()
return heightInInches;
/**
*@return the converted height
*/
public String getNewHeight()
return newHeight;
/**
*@return weight in pounds
*/
public double getWeightInPounds()
return weightInPounds;
/**
*@return models pay per hour rate
*/
public int getPerHourRate()
return perHourRate;
/**
*@return travel
*/
public boolean getTravel()
return travel;
/**
*@return smokes
*/
public boolean getSmokes()
return smokes;
/**
* models first name
*/
public void setFirstName(String whatIsFirstName)
firstName = whatIsFirstName;
/**
* models last name
*/
public void setLastName(String whatIsLastName)
lastName = whatIsLastName;
/**
* models height in inches
*/
public void setHeightInInches(int whatIsHeight)
if (whatIsHeight >0)
heightInInches = whatIsHeight;
/**
* models weight in pounds
*/
public void setWeightInPounds(double whatIsWeight)
if (whatIsWeight >0)
weightInPounds = whatIsWeight;
/**
* can model travel
*/
public void setTravel(boolean canTravel)
travel = canTravel;
/**
* does model smoke
*/
public void setSmokes(boolean smoker)
smokes = smoker;
/**
* Converts to feet and inches
*/
public String convertheightToFeetInches()
int leftOver = (heightInInches %= IN_PER_FOOT);
int newHeight = (heightInInches % IN_PER_FOOT);
return newHeight + "Foot" + leftOver + "Inches";
/**
*
*/
public int calculatePayPerHour()
if (heightInInches >= TALL_INCHES && (weightInPounds <= THIN_POUNDS))
perHourRate = BASE_RATE + TALL_THIN_BONUS;
return perHourRate;
else
perHourRate = BASE_RATE;
return perHourRate;
if (travel) //unreachable statement
perHourRate = BASE_RATE + TRAVEL_BONUS;
return perHourRate;
else
perHourRate = BASE_RATE;
return perHourRate;
if (smokes) //unreachable statement
perHourRate = BASE_RATE - SMOKER_DEDUCTION;
return perHourRate;
else
/**
* Displays details
*/
public void displayInfo()
System.out.print("Name : " + getFirstName() + " ");
System.out.println(getLastName());
System.out.println("Height : " + getNewHeight() + "inches");
System.out.println("Weight : " + getWeightInPounds() + "pounds");
System.out.print("Travel : " + getTravel() + " " );
System.out.print("Smokes : " + getSmokes() );
System.out.println("Hourly rate : " + getPerHourRate() );
【问题讨论】：
下次，请添加有问题的代码。要找到隐藏在单个方法中的单个注释，需要滚动大量代码。 【参考方案1】：这是因为您的程序将从您的第一个 if block 或相应的 else 块返回：-
if (heightInInches >= TALL_INCHES && (weightInPounds <= THIN_POUNDS))
perHourRate = BASE_RATE + TALL_THIN_BONUS;
return perHourRate;
else
perHourRate = BASE_RATE;
return perHourRate;
System.out.println("This will never get printed. And will show compiler error");
所以，两个return语句中的任何一个都会被执行。因此，任何进一步的代码都无法访问。
似乎您希望获得所有service rates 的累积总和以获得最终的perHourRate，为此，您可以从每个if-else 块中删除return statement。然后对于第一个块之后的所有if-else 块，不要将current price 分配给perHourRate，而是执行compound addition +=。
此外，由于您正在处理实例字段 - perHourRate，因此您根本不需要返回它。您对perHourRate 所做的更改可以使用getPerHourRate() 获得。因此，将返回类型更改为void。
您可以尝试将您的calculatePayPerHour 方法更新为以下方法：
public void calculatePayPerHour()
if (heightInInches >= TALL_INCHES && (weightInPounds <= THIN_POUNDS))
perHourRate = BASE_RATE + TALL_THIN_BONUS; // Initial assignment
else
perHourRate = BASE_RATE; // Initial assignment
/** Rest of the assignment will be compound assignment, since you
are now updating the `perHourRate` **/
if (travel)
perHourRate += TRAVEL_BONUS;
// You don't need an else now. Since BASE_RATE is already added
if (smokes)
perHourRate -= SMOKER_DEDUCTION;
【讨论】：
现在很有意义！谢谢你们的帮助:) @JoshuaBaker.. 不客气 :) @JoshuaBaker.. 您可以将答案标记为已接受。【参考方案2】：在您的 calculatePayPerHour 方法中，您有一个 if/else 并且永远不会到达该语句，因为在这两种情况下您都返回一个结果：
if (heightInInches >= TALL_INCHES && (weightInPounds <= THIN_POUNDS))
perHourRate = BASE_RATE + TALL_THIN_BONUS;
return perHourRate; // you return in the if
else
perHourRate = BASE_RATE;
return perHourRate; // you return in the else
... the execution will never reach here
【讨论】：
【参考方案3】：if (heightInInches >= TALL_INCHES && (weightInPounds <= THIN_POUNDS))
perHourRate = BASE_RATE + TALL_THIN_BONUS;
return perHourRate; // <------------
else
perHourRate = BASE_RATE;
return perHourRate; // <------------
无论您的身高或体重如何，这两个返回中的一个都会触发，因此它之后的任何语句都不会被执行。这与下面的代码相同。
if (heightInInches >= TALL_INCHES && (weightInPounds <= THIN_POUNDS))
perHourRate = BASE_RATE + TALL_THIN_BONUS;
else
perHourRate = BASE_RATE;
return perHourRate;
//unreachable
【讨论】：
【参考方案4】：在代码上方的 if/else 中，您已经有 2 个返回语句... 这意味着它永远不会到达下面的代码..
【讨论】：
【参考方案5】： 在您的方法public int calculatePayPerHour() 中，第一个 if else 语句在任何情况下都会返回一个值（在 if 和 else 块中）。
如果您试运行该程序，您将看到 控制流 将永远不会到达此块下方的语句，因此您的异常。
【讨论】：
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