java 函数的参数传递

The Java programming language always uses call by value. That means that the method gets a copy of all parameter values. In particular, the method cannot modify the contents of any parameter variables that are passed to it.

For example, consider the following call:

double percent = 10;harry.raiseSalary(percent);

No matter how the method is implemented, we know that after the method call, the value of percent is still 10.

Let us look a little more closely at this situation. Suppose a method tried to triple the value of a method parameter:

public static void tripleValue(double x) // doesn't work{   x = 3 * x;}

Let's call this method:

double percent = 10;tripleValue(percent);

However, this does not work. After the method call, the value of percent is still 10. Here is what happens: