Common methods of Object class

Common methods of the Object class can be divided into the following categories:

1. Object creation and destruction methods:

• Object(): Constructor, creates a new object.
• finalize(): The method called by the garbage collector, executed before the object is destroyed.

2. How to obtain object information:

• getClass(): Get the runtime class of the object.
• hashCode(): Returns the hash code value of the object.
• toString(): Returns the string representation of the object.

3. Object comparison method:

• equals(Object obj): Compare objects for equality.
• compareTo(T obj): The order of comparison objects.
• clone(): Creates and returns a copy of the object.

4. Thread related methods:

• wait(): Causes the current thread to wait until other threads call the object's notify() or notifyAll() method.
• notify(): Wake up one of the threads waiting for the object.
• notifyAll(): Wake up all threads waiting for the object.

5. Lock related methods:

• synchronized: used to modify code blocks or methods to implement synchronization locks.

6. Use cases:

Here are usage examples for each method:

1. Object creation and destruction methods:

Object obj = new Object();
obj.finalize();

2. Method to obtain object information:

Class<?> clazz = obj.getClass();
int hashCode = obj.hashCode();
String str = obj.toString();

3. Object comparison method:

boolean isEqual = obj1.equals(obj2);
int compareResult = obj1.compareTo(obj2);
Object objCopy = obj.clone();

4. Thread related methods:

synchronized (obj) {
    
    
    try {
    
    
        obj.wait();
    } catch (InterruptedException e) {
    
    
        e.printStackTrace();
    }
}

synchronized (obj) {
    
    
    obj.notify();
}

synchronized (obj) {
    
    
    obj.notifyAll();
}

5. Lock related methods:

public synchronized void synchronizedMethod() {
    
    
    // synchronized 修饰的方法
}

public void synchronizedBlock() {
    
    
    synchronized (this) {
    
    
        // synchronized 修饰的代码块
    }
}