同步以确保另一个线程可以看到对不可变对象的引用

final String immutableString = "Hello, world!";

public class ImmutableObject {
    private final String name;

    public ImmutableObject(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }
}

public class ImmutableObject {
    private volatile String name;

    public void setName(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }
}

import java.util.concurrent.atomic.AtomicReference;

public class ImmutableObject {
    private final AtomicReference<String> name = new AtomicReference<>();

    public void setName(String name) {
        this.name.set(name);
    }

    public String getName() {
        return name.get();
    }
}