I. When you have a parent class, when you create your own object, first call the parent class constructor, there are two cases:
1. When the parent class does not have a constructor (ie, only the default implicit-free-free constructor), first call the implicit constructor, then call its own constructor;
Public class test () {public test () {} public test (int i) {system.out.println (i); public static void main (string args []) {test t = new test (1);} } Class Sup {}
Note: Either parent class has no explicit constructor, or the parent class must declare an explicit-free constructor, both of them! The parent class has other constructors - there is a refinement, but there is no construct The compile period error occurs when a compile period occurs.
2. When the parent class has an explicit constructor - indicates that the non-array constructor is stated, the no-argument is first modulated, and then the constructor is called.
Public class test extends sup {
Public test () {
}
Public Test (INT I) {
System.out.println (i);
}
Public static void main (string args []) {
Test T = New Test (1);
}
}
Class sup {
Public SUP () {// --------- Call the constructor
System.out.println (3);
}
Public SUP (INT I) {
System.out.println (4);
}
}
Second, the class with no parent class is to call your own constructor when you create your own object, and you don't have to call your own no-argument.
Public class test {
Public Test (INT I) {
System.out.println (i);
}
Public static void main (string args []) {
Test T = New Test (1);
}
}
