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What does abstract modifier in Java do?
An abstract keyword is used to declare methods abstract methods and abstract classes. Once a method is declared abstract we should not specify body for those.
Example
public abstract class Sample{
public abstract demo(){
}
}
Error
Sample.java:2: error: invalid method declaration; return type required
public abstract demo(){
^
1 error
And once a class is declared abstract it cannot be instantiated.
Example
public abstract class Sample{
public abstract void demo();
public static void main(String args[]){
new Sample();
}
}
Error
C:\Sample>javac Sample.java Sample.java:4: error: Sample is abstract; cannot be instantiated new Sample(); ^ 1 error
Updated on: 30-Jul-2019
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