Java 中用于垃圾回收的 System.gc()

Sheeraz Gul 2022年4月27日

Java Java Function

System.gc() 是 Java 中提供的用于垃圾收集的 API，它执行自动内存管理。

当我们运行 Java 程序时，可能会有一些不再需要的对象或数据，System.gc() 收集这些数据并删除它们以释放内存。

本教程将演示如何在 Java 中使用 System.gc()。

在 Java 中演示使用 `System.gc()`

System.gc() 可以由系统、开发人员或用于应用程序的外部工具调用。

例子：

package delftstack;
public class System_Gc {

    public static void main(String... args) {
        for (int x = 1; x < 15; x++) {
            Demo_Class New_Demo_Class = new Demo_Class(x);
            System.out.printf("Demo Class Generated, Demo= %s%n", New_Demo_Class.get_Demo());
            System.gc();
        }
    }

    public static class Demo_Class {
        private final int Demo;

        public Demo_Class(int Demo) {
            this.Demo = Demo;
        }

        public int get_Demo() {
            return Demo;
        }

        //the garbage collector will call this method each time before removing the object from memory.
        @Override
        protected void finalize() throws Throwable {
            System.out.printf("-- %s is getting collected in the garbage --%n", Demo);
        }
    }
}

上面的代码给出了 System.gc() 的示例用法，其中一个方法被调用了 14 次，系统收集了 13 次垃圾。

输出：

Demo Class Generated, Demo= 1
Demo Class Generated, Demo= 2
Demo Class Generated, Demo= 3
-- 1 is getting collected in the garbage --
Demo Class Generated, Demo= 4
-- 2 is getting collected in the garbage --
Demo Class Generated, Demo= 5
-- 3 is getting collected in the garbage --
Demo Class Generated, Demo= 6
-- 4 is getting collected in the garbage --
Demo Class Generated, Demo= 7
-- 5 is getting collected in the garbage --
Demo Class Generated, Demo= 8
-- 6 is getting collected in the garbage --
Demo Class Generated, Demo= 9
-- 7 is getting collected in the garbage --
Demo Class Generated, Demo= 10
-- 8 is getting collected in the garbage --
-- 9 is getting collected in the garbage --
Demo Class Generated, Demo= 11
Demo Class Generated, Demo= 12
-- 10 is getting collected in the garbage --
-- 11 is getting collected in the garbage --
Demo Class Generated, Demo= 13
-- 12 is getting collected in the garbage --
Demo Class Generated, Demo= 14
-- 13 is getting collected in the garbage --

System.gc() 不是主要由开发人员使用，因为他们认为它没有用，但它是处理缓存的好工具。

Author: Sheeraz Gul

Sheeraz is a Doctorate fellow in Computer Science at Northwestern Polytechnical University, Xian, China. He has 7 years of Software Development experience in AI, Web, Database, and Desktop technologies. He writes tutorials in Java, PHP, Python, GoLang, R, etc., to help beginners learn the field of Computer Science.

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在 Java 中演示使用 System.gc()

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在 Java 中演示使用 `System.gc()`