Java

Question

这是我的示例代码：

人Class：

public class Person {



private String firstName;
private String lastName;



@Override
public int hashCode() {
    final int prime = 31;
    int result = 1;
    result = prime * result
            + ((firstName == null) ? 0 : firstName.hashCode());
    result = prime * result
            + ((lastName == null) ? 0 : lastName.hashCode());
    return result;
}



@Override
public boolean equals(Object obj) {
    if (this == obj)
        return true;
    if (obj == null)
        return false;
    if (getClass() != obj.getClass())
        return false;
    Person other = (Person) obj;
    if (firstName == null) {
        if (other.firstName != null)
            return false;
    } else if (!firstName.equals(other.firstName))
        return false;
    if (lastName == null) {
        if (other.lastName != null)
            return false;
    } else if (!lastName.equals(other.lastName))
        return false;
    return true;
}



public Person(String firstName,String lastName){

    this.setFirstName(firstName);
    this.setLastName(lastName);
}



public String getFirstName() {
    return firstName;
}



private void setFirstName(String firstName) {
    this.firstName = firstName;
}



public String getLastName() {
    return lastName;
}



private void setLastName(String lastName) {
    this.lastName = lastName;
}

}

Test/Main:

ConcurrentHashMap<Integer,Person> storage = new ConcurrentHashMap<Integer, Person>();
    storage.put(1, new Person("Sally","Solomon"));
    storage.put(2, new Person("Harry","Solomon"));

    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JButton jButton1 = new JButton("Button");


    Person [] personArr= storage.values().toArray(new Person[0]);
    String [] names = new String[personArr.length];

    System.out.println(personArr.length);

    for(int i=0; i<personArr.length; i++){
        System.out.println(personArr[i].getFirstName());
        names[i] = personArr[i].getFirstName() + " " + personArr[i].getLastName();
    }



    final JList jList1 = new JList(names);

问题： 获取 ConcurrectHashMap 中的值并将它们添加到 JList 的正确方法是什么？我的做法是将所有值读入字符串数组并将其添加到 JList。

可以更高效地完成吗？
他们这样做是一种安全的方式吗？或者我只是更新存储并将其添加到 JList？

Answer 1

根据 ConcurrentHashMap's documentation:

Similarly, Iterators and Enumerations return elements reflecting the state of the hash table at some point at or since the creation of the iterator/enumeration. They do not throw ConcurrentModificationException. However, iterators are designed to be used by only one thread at a time.

因此，如果您是唯一一个遍历地图的人，那您就很好，即使另一个线程正在更新它。但请注意，在使用 Swing 时，线程安全主要是在访问 GUI 小部件时提到的——它必须从事件调度线程完成。所以你上面的代码应该是运行从运行nable 传递给 EventQueue#invokeLater

Java - 将 ConcurrentHashMap 添加到 JList 的正确方法？

Java - Correct way of add a ConcurrentHashMap to a JList?

thread-safety

jlist