What does value mean in java

In Java, "Value" usually refers to the value held by an object or variable, including basic types (such as int, double) and reference types (such as objects). Primitive types store actual values, while reference types store references to objects. Objects in Java are passed by reference, and modifications to the reference of the object can affect the original object. Additionally, some classes, such as String, are immutable, meaning their value cannot be changed after creation.

Value in Java

In Java, the word "Value" usually refers to the value held by an object or variable. Some value. These values ​​can be primitive types (such as int, double, boolean) or reference types (such as objects).

Basic Types

Basic types store their values ​​directly and cannot change the referenced value. For example:

int myInt = 10;
// myInt 现在包含值 10

Reference type

Reference type stores a reference to an object rather than the actual value of the object. Therefore, the referenced object can be changed. For example:

Integer myInteger = new Integer(10);
// myInteger 现在引用一个包含值 10 的 Integer 对象
myInteger = new Integer(20);
// myInteger 现在引用一个包含值 20 的 Integer 对象

Value and Reference

In Java, objects are passed by reference. This means that when you pass an object reference, you are actually passing a reference to that object. For example:

public void changeValue(Integer myInteger) {
  myInteger = new Integer(30);
}

Integer myInteger = new Integer(10);
changeValue(myInteger);
System.out.println(myInteger); // 输出：30

In this example, although the value of myInteger is reassigned in the changeValue method, this also modifies the actual object passed to the method .

Immutable types

In Java, certain classes (such as wrapper classes for String and Integer) are immutable. This means that once these objects are created, their values ​​cannot be changed.

String myString = "Hello";
// myString 现在包含字符串 "Hello"
myString = "World";
// 不会改变 myString 的值，而是创建一个新的 String 对象

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