To implement a thread-safe class in Java, you need to ensure that multiple threads can safely use and modify its state without causing data corruption, race conditions, or other synchronization issues. There are several techniques and mechanisms you can use to make a class thread-safe in Java:

1. Synchronization:
   One of the most common ways to achieve thread safety is by using synchronization. You can synchronize methods or code blocks using the `synchronized` keyword. This prevents multiple threads from executing the synchronized code simultaneously. For example:

```java
public class ThreadSafeClass {
    private int count = 0;

    public synchronized void increment() {
        count++;
    }

    public synchronized int getCount() {
        return count;
    }
}
```

In this example, the `increment` and `getCount` methods are synchronized, ensuring that only one thread can execute them at a time.

2. Use Thread-Safe Data Structures:
   Java provides thread-safe data structures in the `java.util.concurrent` package. You can use classes like `ConcurrentHashMap`, `CopyOnWriteArrayList`, and `ConcurrentLinkedQueue` to manage shared data safely without the need for explicit synchronization.

```java
import java.util.concurrent.ConcurrentHashMap;

public class ThreadSafeClass {
    private ConcurrentHashMap<String, Integer> data = new ConcurrentHashMap<>();

    public void addToData(String key, int value) {
        data.put(key, value);
    }

    public int getValue(String key) {
        return data.get(key);
    }
}
```

3. Immutable Objects:
   Designing your classes to be immutable (unchangeable) ensures thread safety because once an object is created, it cannot be modified. Immutable objects are inherently thread-safe and can be safely shared among multiple threads.

```java
public final class ImmutableClass {
    private final int value;

    public ImmutableClass(int value) {
        this.value = value;
    }

    public int getValue() {
        return value;
    }
}
```

4. Use the `volatile` Keyword:
   The `volatile` keyword can be used to indicate that a variable's value may be modified by multiple threads, ensuring that changes made by one thread are visible to others. It's often used for simple flags or status indicators.

```java
public class ThreadSafeClass {
    private volatile boolean flag = false;

    public void setFlag(boolean value) {
        flag = value;
    }

    public boolean isFlag() {
        return flag;
    }
}
```

5. Locks and Mutexes:
   You can use explicit locks provided by the `java.util.concurrent.locks` package, such as `ReentrantLock`, to control access to critical sections of your code. Locks offer more fine-grained control over synchronization than the `synchronized` keyword.

```java
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class ThreadSafeClass {
    private int count = 0;
    private Lock lock = new ReentrantLock();

    public void increment() {
        lock.lock();
        try {
            count++;
        } finally {
            lock.unlock();
        }
    }

    public int getCount() {
        lock.lock();
        try {
            return count;
        } finally {
            lock.unlock();
        }
    }
}
```

When implementing a thread-safe class, consider the specific requirements of your application and choose the synchronization mechanism that best suits your needs. Keep in mind that synchronization can introduce performance overhead, so it's essential to strike a balance between thread safety and performance optimization.