import java.lang.ref.PhantomReference;
import java.lang.ref.ReferenceQueue;

public final class Main {

    public static void main(String[] args) throws InterruptedException {
        ReferenceQueue<byte[]> queue = new ReferenceQueue<>();
        PhantomReference<byte[]> ref = new PhantomReference<>(new byte[1024 * 1024 * 5], queue);

        System.out.println(queue.poll());
        System.out.println("第一次gc");
        System.gc();
        Thread.sleep(300L);
        System.out.println(queue.poll());
        System.out.println("第二次gc");
        System.gc();
        byte[] bytes1 = new byte[1024 * 1024 * 6];
        System.out.println("ending");
    }
}

// from https://gist.github.com/youribonnaffe/03176be516c0ed06828ccc7d6c1724ce
JacksonAnnotationIntrospector implicitRecordAI = new JacksonAnnotationIntrospector() {
    @Override
    public String findImplicitPropertyName(AnnotatedMember m) {
        if (m.getDeclaringClass().isRecord()) {
            if (m instanceof AnnotatedParameter parameter) {
                return m.getDeclaringClass().getRecordComponents()[parameter.getIndex()].getName();
            }
        }
        return super.findImplicitPropertyName(m);
    }
};
objectMapper.setAnnotationIntrospector(implicitRecordAI);

public class Main {
    static class Class1 {
        Object object;
    }
    static class Class2 {
        Class1 class1;
        public Class1 getClass1() {
            return class1;
        }
    }
    static Class2 class2;
    private static Object get(int i) {
        return null;
    }
    // 打印NPE的message
    private static void printNPE(Runnable runnable) {
        try {
            runnable.run();
        } catch (NullPointerException e) {
            System.err.println(e.getMessage());
        }
    }
    public static void main(String[] args) {
        Class2 class21 = null;
        printNPE(() -> {
            // 1. getstatic为null
            // Cannot invoke "Main$Class2.getClass1()" because "Main.class2" is null
            System.out.println(class2.getClass1().object.toString());
        });
        Class2 class22 = new Class2();
        printNPE(() -> {
            // 2. 调用函数结果为null
            // Cannot read field "object" because the return value of "Main$Class2.getClass1()" is null
            System.out.println(class22.getClass1().object.toString());
        });
        class22.class1 = new Class1();
        printNPE(() -> {
            // 3. 函数调用后，getfield为null
            // Cannot invoke "Object.toString()" because "Main$Class2.getClass1().object" is null
            System.out.println(class22.getClass1().object.toString());
        });
        printNPE(() -> {
            // 4. 链式getfield
            // Cannot invoke "Object.toString()" because "class22.class1.object" is null
            System.out.println(class22.class1.object.toString());
        });
        Integer[] ary1 = null;
        printNPE(() -> {
            // 5. 对null执行aaload
            // Cannot load from object array because "ary1" is null
            System.out.println(ary1[0].intValue());
        });
        Integer[] ary2 = new Integer[1];
        printNPE(() -> {
            // 6. iconst_0+aaload后为null
            // Cannot invoke "java.lang.Integer.intValue()" because "ary2[0]" is null
            System.out.println(ary2[0].intValue());
        });
        printNPE(() -> {
            int i = 0;
            // 7. iconst_0+iload_1后为null
            // Cannot invoke "java.lang.Integer.intValue()" because "ary2[i]" is null
            System.out.println(ary2[i].intValue());
        });
        printNPE(() -> {
            int i = 0;
            // 8. iconst_0+iadd后为null
            // Cannot invoke "java.lang.Integer.intValue()" because "ary2[...]" is null
            System.out.println(ary2[i + 0].intValue());
        });
        printNPE(() -> {
            // 9. invokevirtual结果为null
            // Cannot invoke "Object.toString()" because the return value of "Main.get(int)" is null
            System.out.println(Main.get(1).toString());
        });
    }
}

import java.util.Optional;

public class JavaBugTest {

    public static <T, E extends Throwable> T execute(RetryCallback<T, E> retryCallback) throws E {
        return retryCallback.doWithRetry(new Object());
    }

    public static void main(String[] args) {
        Optional.ofNullable(execute((param) -> new Object()))
                .ifPresent(s -> System.out.println(s));
    }
}

public interface RetryCallback<T, E extends Throwable> {
    T doWithRetry(Object var1) throws E;
}