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final, finally and finalize in Java
The final keyword can be used with class method and variable. A final class cannot be inherited, a final method cannot be overridden and a final variable cannot be reassigned.
The finally keyword is used to create a block of code that follows a try block. A finally block of code always executes, whether or not an exception has occurred. Using a finally block allows you to run any cleanup-type statements that you just wish to execute, despite what happens within the protected code.
The finalize() method is used just before object is destroyed and can be called just prior to object creation.
Example final
public class Tester {
final int value = 10;
// The following are examples of declaring constants:
public static final int BOXWIDTH = 6;
static final String TITLE = "Manager";
public void changeValue() {
value = 12; // will give an error
}
public void displayValue(){
System.out.println(value);
}
public static void main(String[] args) {
Tester t = new Tester();
t.changeValue();
t.displayValue();
}
}Output
Compiler will throw an error during compilation.
Tester.java:9: error: cannot assign a value to final variable value value = 12; // will give an error ^ 1 error
Example finally
public class Tester {
public static void main(String[] args) {
try{
int a = 10;
int b = 0;
int result = a/b;
}catch(Exception e){
System.out.println("Error: "+ e.getMessage());
}
finally{
System.out.println("Finished.");
}
}
}Output
Error: / by zero Finished.
Example finalize
public class Tester {
public void finalize() throws Throwable{
System.out.println("Object garbage collected.");
}
public static void main(String[] args) {
Tester t = new Tester();
t = null;
System.gc();
}
}Output
Object garbage collected.
Updated on: 29-Jul-2021
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