[OCAJP]欄位的初始值

Given:

public class Whizlabs {

    private String name;
    private boolean pass;

    public static void main(String[] args) {
        Whizlabs wb = new Whizlabs();
        System.out.print("name = " + wb.name);
        System.out.print(",pass = " + wb.pass);
    }
}

public class Whizlabs {

private String name;

private boolean pass;

public static void main(String[] args) {

Whizlabs wb = new Whizlabs();

System.out.print("name = " + wb.name);

System.out.print(",pass = " + wb.pass);

}

What would be the output, if it is executed as a program?

name =, pass =

name = null, pass = null

name = null, pass = false

name = null pass = true

E. Compile error.

題解

Java的類別或是物件欄位會按照不同資料型態自動給定初始值。初始值如下：

String、Object：null
byte、short、int、long、float、double：0
char：\0
boolean：false

MagicLen

MagicLen

內容

[OCAJP]欄位的初始值

題解

關於作者

Magic Len

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