可變物件具有可以修改的欄位；不可變物件沒有在建立物件後可以更改的欄位。不可變物件是指其狀態在建立後就無法變更的物件。可變和不可變是java中的兩類物件。在本文中，我們將了解 java 中可變物件和不可變物件之間的差異。此外，我們還將看到 Java 程式碼範例，顯示 Java 中可變類別和不可變類別之間的差異。
廣告 該類別中的熱門課程 JAVA 掌握 - 專業化 | 78 課程系列 | 15 次模擬測驗以下是 Mutable 與 Immutable Java 之間的 6 大差異：
以下是 Java 中可變物件和不可變物件之間的主要區別：
讓我們討論 Mutable 與 Immutable Java 之間的主要比較：
可變
|
Mutable |
Immutable |
| Java Mutable object can be modified after its creation. | Java Immutable object cannot be modified after its creation. |
| No new object is formed when changes are made to an existing object. | Whenever an existing object is changed, a new object is formed. |
| It provides methods to change the content of an object. | It does not provide methods for changing the content of an object. |
| Getter and setter methods are present in mutable classes. | Only getter methods are present and not setter methods. |
| Mutable classes may or may not be thread-safe. | Immutable classes are thread-safe by default. |
| Some common examples of mutable classes in java are StringBuffer, StringBuilder, and java.util.Date. | All Legacy classes, Wrapper classes, String class, are common examples of Immutable classes in java. |
不可變
可變與不可變 Java 的範例如下：
現在我們將看到 Java 程式碼範例，展示了在 Java 中建立可變類別和不可變類別。
代碼：
package com.edubca.mutabledemo;
public class MutableDemo {
private String studentName;
private int rollNumber;
MutableDemo (String studentName, int rollNumber) {
this.studentName = studentName;
this.rollNumber = rollNumber;
}
public String getStudentName() {
return studentName;
}
// this setter can modify the name
public void setStudentName(String studentName) {
this.studentName = studentName;
}
public int getRollNumber() {
return rollNumber;
}
// this setter can modify roll number
public void setRollNumber(int rollNumber) {
this.rollNumber = rollNumber;
}
public static void main(String[] args) {
MutableDemo obj = new MutableDemo ("John" , 100);
System.out.println("Original Name is " + obj.getStudentName());
System.out.println("Original Roll Number is " + obj.getRollNumber());
// update the name, and roll number as is mutable
obj.setStudentName("James");
obj.setRollNumber(102);
System.out.println("Modified Name is " + obj.getStudentName());
System.out.println("Modified Roll Number is " + obj.getRollNumber());
}
}輸出：
上面的程式碼展示了在java中使用getter和setter創建一個可變類別。
現在我們將了解如何在 Java 中建立不可變類別。
代碼：
package com.edubca.immutabledemo;
public final class ImmutableDemo {
final String studentName;
final int rollNumber;
public ImmutableDemo (String studentName, int rollNumber) {
this.studentName = studentName;
this.rollNumber = rollNumber;
}
public String getStudentName() {
return studentName;
}
public int getRollNumber() {
return rollNumber;
}
public static void main(String[] args) {
ImmutableDemo obj = new ImmutableDemo ("John" , 100);
// Since no getters are available contents cannot be modified.
// Also as variables are declared final they cannot be modified
System.out.println("Name is " + obj.getStudentName());
System.out.println("Roll Number is " + obj.getRollNumber());
}
}輸出：
上面的程式碼顯示了java不可變類別的創建。建立不可變類別時應牢記以下幾點：
透過上面的討論，我們清楚地了解了java中可變和不可變的區別。此外，我們還看到了 Java 範例，展示如何建立可變類別和不可變類別。值得注意的是，不可變類別預設是線程安全的，而可變類別可能是也可能不是線程安全的。
以上是可變與不可變 Java的詳細內容。更多資訊請關注PHP中文網其他相關文章！
