CODEWITHSUNDEEP
java
devdoe
devdoe

Reputation: 4325

Typecasting in java

int n ;
n= (int)( javax.swing.JOptionPane.showInputDialog(null,"enter a 3 digit no."));

Why does the above gives error[required int, found string] and the below one works fine ?

int n ;
n= Integer.parseInt( javax.swing.JOptionPane.showInputDialog(null,"enter a 3 digit no."));

Upvotes: 3

Views: 2851

Answers (3)

David Harkness
David Harkness

Reputation: 36542

Integer.parseInt doesn't use casting but rather a simple algorithm to interpret the digits in the string as a number. Casting is done by the JVM directly on the primitive value or the compiler on the object reference. It can turn 4.5 into 4 (type conversion as it changes the underlying value) and ArrayList into List (reference casting as it doesn't modify the instance), but it cannot parse or format numbers natively.

Upvotes: 9

Kevin
Kevin

Reputation: 56089

Java only lets you make valid casts, i.e. ones it knows how to make. Casting a string to an int is nonsensical; parsing it is not.

Upvotes: 1

Marko Topolnik
Marko Topolnik

Reputation: 200168

Type casting is not type conversion, don't confuse the terms. Casting means reinterpreting the same binary representation as a value of another type. In Java there are conversions, but only between primitive numeric values. String is a reference type, I guess you know that.

Upvotes: 8

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