Ponekad moramo provjeriti vrstu podataka varijable da bismo izračunali podatke jer možemo izvesti logičku operaciju s istom vrstom varijabli. Kako bismo provjerili tip podataka, koristimo metodu getClass() i getSimpleName() za dobivanje klase odnosno njenog imena. U ovom odjeljku ćemo raspravljati kako provjeriti vrstu podataka u Javi?
Implementirajmo kod za dobivanje tipova podataka varijabli. Prvo uzimamo unos od korisnika, a zatim pronalazimo tip podataka varijabli u kojima će biti pohranjen korisnički unos.
CheckDataTypeExample.java
import java.util.*; // create class CheckDataTypeExample to check the datatype of the variable public class CheckDataTypeExample { // main() method start public static void main(String args[]) { // declare variables int intData; char charData; // create Scanner class object to take input from user Scanner sc = new Scanner(System.in); // take input from the user to initialize variables System.out.println('Enter a String value:'); String str = sc.nextLine(); System.out.println('Enter Integer value:'); intData = sc.nextInt(); System.out.println('Enter Character value:'); charData = sc.next().charAt(0); // close Scanner class object sc.close(); // show datatypes of variables by using getClass() and getSimpleName() methods System.out.println(intData + ' is of type ' + ((Object)intData).getClass().getSimpleName()); System.out.println(charData + ' is of type ' + ((Object)charData).getClass().getSimpleName()); System.out.println(str + ' is of type ' + str.getClass().getSimpleName()); } } Izlaz:
Sada imamo posebnu metodu, tj. getType() koje osiguravaju java.lang.reflect.Field i Character klase. Razmotrimo metodu getType() obje klase jednu po jednu.
Field.getType()
The getType() metoda od Polje klasa se koristi za dobivanje tipa polja definiranog objektom Field. Povratna vrijednost nam pomaže u identificiranju tipa polja.
java switch izjava
Sintaksa:
Sintaksa getType() metoda je sljedeća:
public String getType()
Parametar: Ne prihvaća nikakav argument kao parametar.
Povratak: Vraća objekt klase koji nam pomaže u identificiranju tipa polja.
Uzmimo primjer metode getType() i shvatimo kako funkcionira:
GetTypeExample1.java
// import required classes and package if any import java.lang.reflect.Field; // create class GetTypeExample1 to get the type of the Field public class GetTypeExample1 { // main() method start public static void main(String[] args)throws Exception { //get the name field object by using getField() method Field nameField = Student.class.getField('name'); // use getTyoe() method of the Field to get the type of name field Class value = nameField.getType(); // print the type of name field System.out.println('The type of the name field is ' + value); //get the totalMarks field object by using getField() method Field marksField = Student.class.getField('totalMarks'); // use getTyoe() method of the Field to get the type of totalMarks field value = marksField.getType(); // print the type of name field System.out.println('The type of the totalMarks field is ' + value); //get the totalFees field object by using getField() method Field feesField = Student.class.getField('totalFees'); // use getTyoe() method of the Field to get the type of name field value = feesField.getType(); // print the type of the totalFees field System.out.println('The type of the totalFees field is ' + value); } } // create a simple student class class Student { // declare and initialize variables public static String name = 'John'; public static double totalMarks = 380; public static float totalFees = 3413.99f; // getter for student name public static String getName() { return name; } // setter for student name public static void setName(String stdName) { name = stdName; } // getter for totalMarks public static double getTotalMarks() { return totalMarks; } // setter for totalMarks public static void setMarks(double marks) { totalMarks = marks; } // getter for totalFees public static float getTotalFees() { return totalFees; } // setter for totalFees public static void setFees(float fees) { totalFees = fees; } } Izlaz:
strojopis datum
Korištenje metode Field.getType().
The getType() metoda od Lik klasa se koristi za dobivanje opće kategorije zadanog znaka. Metoda getType() dolazi s dvije varijacije na temelju parametra, tj. Character.getType(char ch) i Character.getType(int codePoint) .
Metoda getType() koja uzima char kao parametar ne može rukovati dodatnim znakovima, dok metoda getType() koja uzima int kao parametar može rukovati dodatnim znakovima.
Sintaksa:
The getType() metoda Lik klasa ima sljedeću sintaksu:
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public static int getType(char ch) public static int getType(int codePoint)
Parametar: Prva varijacija metode getType() prihvaća parametar tipa char a druga varijacija metode prihvaća parametar tipa int, tj. codePoint.
Povratak: Obje metode vraćaju vrijednost cijelog broja koja označava opću kategoriju znaka.
Uzmimo primjer metode getType() i shvatimo kako funkcionira:
GetTypeExample2.java
// import required classes and package if any // create class GetTypeExample2 to get the general category of the given character public class GetTypeExample2 { // main() method start public static void main(String[] args)throws Exception { // use setter to set ch1, ch2 in CharData CharData.setChar1('C'); CharData.setChar2('%'); // use getter to get char1 and char2 char char1 = CharData.getChar1(); char char2 = CharData.getChar2(); // use getType() method of Character class int val1 = Character.getType(char1); int val2 = Character.getType(char2); // print categories of char1 and char2 System.out.println('The category of ' +char1 + ' is '+ val1); System.out.println('The category of ' +char2 + ' is '+ val2); } } // create a simple CharData class class CharData { // declare variables of type char static char ch1, ch2; // getter for ch1 public static char getChar1() { return ch1; } // setter for ch1 public static void setChar1(char ch) { ch1 = ch; } // getter for ch2 public static char getChar2() { return ch2; } // setter for ch2 public static void setChar2(char ch) { ch2 = ch; } } Izlaz:
GetTypeExample3.java
// import required classes and package if any import java.lang.reflect.Field; // create class GetTypeExample3 to get the general category of the given character public class GetTypeExample3 { // main() method start public static void main(String[] args)throws Exception { // use setter to set code1, code2 in CodePoint CodePoint.setCodePoint1(0x0037); CodePoint.setCodePoint2(0x016f); // use getter to get code1 and code2 int code1 = CodePoint.getCodePoint1(); int code2 = CodePoint.getCodePoint2(); // use getType() method of Character class int val1 = Character.getType(code1); int val2 = Character.getType(code2); // print categories of char1 and char2 System.out.println('The category of ' +code1+ ' is '+ val1); System.out.println('The category of ' +code2+ ' is '+ val2); } } // create a simple CodePoint class class CodePoint { // declare variables of type int static int codePoint1, codePoint2; // getter for codePoint1 public static int getCodePoint1() { return codePoint1; } // setter for codePoint1 public static void setCodePoint1(int code1) { codePoint1 = code1; } // getter for codePoint2 public static int getCodePoint2() { return codePoint2; } // setter for codePoint2 public static void setCodePoint2(int code2) { codePoint2 = code2; } } Izlaz:
