使用同步方法而不是同步块有优势吗？ [英] Is there an advantage to use a Synchronized Method instead of a Synchronized Block?

问题描述

任何人都可以告诉我同步方法对同步块的优点与一个例子？

Can any one tell me the advantage of synchronized method over synchronized block with an example?

推荐答案

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也许唯一一个（但我不会称之为优势）是你不需要包含对象引用 this 。

Perhaps the only one ( but I wouldn't call it advantage ) is you don't need to include the object reference this.

方法：

public synchronized void method() { // blocks "this" from here.... 
    ...
    ...
    ...
} // to here

封锁：

public void method() { 
    synchronized( this ) { // blocks "this" from here .... 
        ....
        ....
        ....
    }  // to here...
}

没有优势。

阻止 do 优于方法，最重要的是灵活性，因为您可以使用其他对象作为锁，而同步方法将锁定完整类。

Blocks do have advantages over methods, most of all in flexibility because you can use other object as lock whereas syncing the method would lock the complete class.

比较：

// locks the whole object
... 
private synchronized void someInputRelatedWork() {
    ... 
}
private synchronized void someOutputRelatedWork() {
    ... 
}

Vs。

// Using specific locks
Object inputLock = new Object();
Object outputLock = new Object();

private void someInputRelatedWork() {
    synchronize(inputLock) { 
        ... 
    } 
}
private void someOutputRelatedWork() {
    synchronize(outputLock) { 
        ... 
    }
}

如果方法增长，你仍然可以保持同步部分分离：

Also if the method grows you can still keep the synchronized section separated:

 private void method() {
     ... code here
     ... code here
     ... code here
    synchronized( lock ) { 
        ... very few lines of code here
    }
     ... code here
     ... code here
     ... code here
     ... code here
}

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