asked on interface inheritance of same method
6. Multiple inheritance of state is not allowed:
Remember that Java does not allow a class inherits two or more classes directly. To understand why multiple inheritance is not allowed, consider the following example:
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public class A {
public void methodA() {
}
public void foo() {
}
}
public class B {
public void methodB() {
}
public void foo() {
}
}
Suppose that we want to write a class C that extends both A and B like this:
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public class C extends A, B {
public void methodC() {
foo();
}
}
As you can see, both A and B has a method called foo(), so which foo() method the class C invokes exactly? from A or B? This case is ambiguous hence Java does not allow.
7. Multiple inheritance of type is allowed:
This means Java does allow multiple inheritance between interfaces. For example:
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public interface X {
public void methodX();
}
public interface Y {
public void methodY();
}
public interface Z extends X, Y {
public void methodZ();
}
This is allowed because interfaces do not have concrete methods, thus there is no ambiguity.
Likewise, we can have a class implements multiple interfaces:
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public class Sub implements X, Y, Z {
public void methodX() { }
public void methodY() { }
public void methodZ() { }
}
if both Interface X and Interface Y has same method called methodAB what happens?
6. Multiple inheritance of state is not allowed:
Remember that Java does not allow a class inherits two or more classes directly. To understand why multiple inheritance is not allowed, consider the following example:
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public class A {
public void methodA() {
}
public void foo() {
}
}
public class B {
public void methodB() {
}
public void foo() {
}
}
Suppose that we want to write a class C that extends both A and B like this:
1
2
3
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5
public class C extends A, B {
public void methodC() {
foo();
}
}
As you can see, both A and B has a method called foo(), so which foo() method the class C invokes exactly? from A or B? This case is ambiguous hence Java does not allow.
7. Multiple inheritance of type is allowed:
This means Java does allow multiple inheritance between interfaces. For example:
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11
public interface X {
public void methodAB();
}
public interface Y {
public void methodAB();
}
public interface Z extends X, Y {
public void methodZ();
}
This is allowed because interfaces do not have concrete methods, thus there is no ambiguity.
Likewise, we can have a class implements multiple interfaces:
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2
3
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public class Sub implements X, Y, Z {
public void methodX() { }
public void methodY() { }
public void methodZ() { }
}
in this case
public interface Z extends X, Y {
public void methodAB();
}
something like below
package MultipleInheritanceType;
public interface X {
public void methodAB();
}
package MultipleInheritanceType;
public interface Y {
public void methodAB();
}
package MultipleInheritanceType;
public interface Z extends X, Y {
public void methodABC();
}
package MultipleInheritanceType;
public class Sub implements X, Y, Z {
@Override
public void methodABC() {
// TODO Auto-generated method stub
}
@Override
public void methodAB() {
// TODO Auto-generated method stub
}
/*public void methodX() { }
public void methodY() { }
public void methodZ() { }*/
}
Please advise
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Last Comment
girionis
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