What are the usage scenarios of anonymous objects in Java?

Anonymous objects do not need to create class instances and can be created and used immediately using new when needed. Their uses include: Short-term use: When used as a one-time operation. Anonymous callback: when passing an object as a function parameter. Custom comparator: when sorting a collection or array. Dynamic proxy: When creating a proxy using an anonymous inner class. Event handling: When registering an event listener.

Purposes of Anonymous Objects in Java

Anonymous objects are objects that do not require the creation of class instances. They are created when needed using the keyword new and used immediately.

Use scenarios:

• Short-term use: When only one object is needed for a one-time operation.
• Anonymous callback: When an object needs to be passed as a parameter to a method that accepts a function object.
• Custom Comparator: Create a temporary comparator to sort a collection or array.
• Dynamic Proxy: By using an anonymous inner class to create a dynamic proxy, there is no need to create a separate proxy class.
• Event handling: In an event-driven environment, anonymous objects can be used to register event listeners.

Practical case:

Anonymous comparator:

// 自定义比较器，比较两个字符串的长度
Comparator<String> lengthComparator = new Comparator<String>() {
    @Override
    public int compare(String s1, String s2) {
        return s1.length() - s2.length();
    }
};

Anonymous thread:

// 创建一个匿名线程并立即启动它
new Thread(new Runnable() {
    @Override
    public void run() {
        System.out.println("匿名线程正在运行");
    }
}).start();

Anonymous callbacks:

// 将一个匿名函数对象传递给一个方法
doSomething(new Function<String, Integer>() {
    @Override
    public Integer apply(String s) {
        return s.length();
    }
});

Anonymous objects provide the flexibility to create temporary objects without defining a permanent class. They are useful in situations such as requiring short-term use, anonymous callbacks, or custom comparators.

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