private static void changeString(String s) {
s = new String("new string");
}
public static void main(String[] args) {
String s = new String("old string");
changeString(s);
System.out.println(s); // expect "new string"
}
How could I make the output of "new string" happen with s as the only argument to method changeString?
thanks.
Java main method is the entry point of any java program. Its syntax is always public static void main(String[] args) . You can only change the name of String array argument, for example you can change args to myStringArgs .
In order to pass the reference, we pass the object of the class in the place of the actual parameter and the formal parameter of a class object type has the same reference to each other that's why with the help of the formal parameter object of class any changes will be reflected in both objects formal and actual ...
Pass-by-value means that when you call a method, a copy of each actual parameter (argument) is passed. You can change that copy inside the method, but this will have no effect on the actual parameter. Unlike many other languages, Java has no mechanism to change the value of an actual parameter.
Arguments in Java are always passed-by-value. During method invocation, a copy of each argument, whether its a value or reference, is created in stack memory which is then passed to the method.
In Java arguments are passed by value, object arguments pass a reference to the object, this means that you can change the reference of the argument, but that does not change the object you passed the reference to. You have two possibilities, return the new object (preferred) or pass reference to a container that can receive the new reference (collection, array, etc.) For example:
private static String changeStringAndReturn(String s) {
return new String("new string");
}
private static void changeStringInArray(String[] s) {
if (null != s && 0 < s.length) {
s[0] = new String("new string");
}
}
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