Introduce Variable

To increase readability and sometimes to increase performance, introducing temporary variables into a method is necessary. For example, consider the code in Listing 7.4.

Listing 7.4. Calculate Vacation Days
public int getVacationDays( ) { 
 int X; 

 X = (int)(10 * java.lang.Math.random()); 

 if (X + 2 < 5 ) 
 { 
   return X + 2; 
 } 
 if (X + 2 > 5 ) 
 { 
   return X + 2 - (X + 2) / 7; 
 } 

 if (X + 2 == 5) 
 { 
   return 5; 
 } 
   return X; 
 }

In Listing 7.4, notice the number of times that X + 2 is used. Every time that expression is evaluated, a calculation takes place. Calculations are typically one of the more CPU-intensive operations.

By using Introduce Variable, a temporary variable can be created to replace the expression X + 2. To display the Introduce ...

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