java 中的 java.lang.ref.SoftReference 类
原文:https://www . geesforgeks . org/Java-lang-ref-soft reference-class-in-Java/
当我们用 Java 创建一个对象时，默认情况下对象不是软的。要创建一个软引用对象，我们必须明确地将其指定给 JVM 。在软引用中，即使对象可以进行垃圾收集，也不会进行垃圾收集，直到 JVM 急需内存。当 JVM 内存不足时，对象会从内存中清除。
为什么使用软参考对象？
创建软引用对象时，它被标记为垃圾收集。但是，除非 JVM 内存不足，否则不会进行垃圾收集。
软引用类中的构造函数:
| 构造函数参数 | 构造函数描述 | | --- | --- | | 软引用(参考文献) | Creates a new soft reference that references the given object. | | 软引用(T 引用，引用队列) q) | Create a new soft reference that references the given object and registers in the given queue. |get()方法:
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to show the demonstration
// of get() method of SoftReference Class
import java.lang.ref.SoftReference;
class GFG {
public static void main (String[] args) {
// creating a strong object of MyClass
MyClass obj = new MyClass ();
// creating a weak reference of type MyClass
SoftReference<MyClass> sobj = new SoftReference<>(obj);
System.out.println ("-> Calling Display Function using strong object:");
obj.Display ();
System.out.println ("-> Object set to null");
obj = null;
// Calling the get() method
obj = sobj.get();
System.out.println ("-> Calling Display Function after retrieving from soft Object");
obj.Display ();
}
}
class MyClass {
void Display ()
{
System.out.println ("Display Function invoked ...");
}
}
Output
-> Calling Display Function using strong object:
Display Function invoked ...
-> Object set to null
-> Calling Display Function after retrieving from soft Object
Display Function invoked ...
显示软引用类的 enqueue()和 isEnqueued()方法的示例:
Java 语言(一种计算机语言，尤用于创建网站)
// Java program demonstrating all the methods
// of SoftRefernce Class
import java.lang.ref.SoftReference;
class GFG {
public static void main (String [] args) {
// Creating object of Class X
X obj = new X ();
// Creating a soft reference of type X
SoftReference <X> softobj = new SoftReference <X> (obj);
System.out.println ("-> Retrieving object from Soft Reference using get ()");
softobj.get().show();
System.out.println ("-> Is it possible to queue object using enqueue ()");
System.out.println (softobj.enqueue ());
System.out.println ("-> Checking if reference is queued using isEnqueued ()");
System.out.println (softobj.isEnqueued ());
}
}
class X {
void show()
{
System.out.println ("show () from X invoked..");
}
}
Output
-> Retrieving object from Soft Reference using get ()
show () from X invoked..
-> Is it possible to queue object using enqueue ()
false
-> Checking if reference is queued using isEnqueued ()
false
从引用类继承的方法:
| Method name | 方法描述 | | --- | --- | | clear away | Clear this reference object. | | [Join the team ()] | Add this reference object to the queue where it is registered, if any. | | get() | Returns the referent of the reference object. | | isEqueued() | Tell whether this reference object has been enqueued, whether it is a program enqueued or a garbage collector enqueued. |版权属于：月萌API www.moonapi.com，转载请注明出处
