一次对象自我拯救的演示（GC、finalize()、F-Queue、finalilzer）

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package lime.jvm._003._002._004;

import java.util.concurrent.TimeUnit;

/**
 * @Author : Liangmy
 * @Description :
 * @Date : Created in 2019/12/28 下午4:34
 * @Modified By :
 */
public class FinalizeEscapeGC {
    public static FinalizeEscapeGC SAVE_HOOK = null;

    public void isAlive() {
        System.out.println("yes, i am still alive :)");
    }

    @Override
    protected void finalize() throws Throwable {
        super.finalize();
        System.out.println("finalize method executed!");
        SAVE_HOOK = this;
    }

    public static void main(String[] args) throws InterruptedException {
        SAVE_HOOK = new FinalizeEscapeGC();

        // 对象第一次成功拯救自己
        SAVE_HOOK = null;

        System.gc();
        // 因为finalize方法优先级很低，所以暂停0.5秒以等待它
        TimeUnit.MILLISECONDS.sleep(500);
        if(SAVE_HOOK != null){
            SAVE_HOOK.isAlive();
        }else{
            System.out.println("no, i am dead :(");
        }

        // 下面这段代码与上面的完全相同，但是这次自救却失败了
        SAVE_HOOK = null;
        System.gc();
        // 因为finalize方法优先级很低，所以暂停0.5秒以等待它
        TimeUnit.MILLISECONDS.sleep(500);
        if(SAVE_HOOK != null){
            SAVE_HOOK.isAlive();
        }else{
            System.out.println("no, i am dead :(");
        }

    }
}

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finalize method executed!
yes, i am still alive :)
no, i am dead :(