非静态字段在只有一个实例的类中有意义吗

Question

public class TestData {

    private ThreadLocal<Data> threadLocalData = new ThreadLocal<>();
    private UUID id = UUID.randomUUID();
    private static final TestData testData = new TestData();
    private static final Logger ogger = LoggerFactory.getLogger("data");


    private TestData() {
    }

    public static TestData getTestData() {
        return testData;
    }

    public void addTestData(String key) {
        Data data = new Data(key);

        threadLocalData.set(data);
    }

    public ThreadLocal<Data> getThreadLocalData() {
        return threadLocalData;
    }
}

TestData.getTestData().getThreadLocalData().set(new Data());

private static final TestData testData = new TestData();

那么类中有非静态成员有什么意义吗？

    private ThreadLocal<Data> threadLocalData = new ThreadLocal<>();
    private UUID id = UUID.randomUUID();

如果是，那么使用testData实例的每个线程是否都有这些非静态成员的单独副本？

Answer 1

有非静态成员有意义吗

当然，因为仍然存在类的一些实例

这些非静态成员有单独的副本