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Java Synchronized 解析

Synchronized Methods

代码示例：

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public class SynchronizedCounter {
    private int c = 0;

    public synchronized void increment() {
        c++;
    }

    public synchronized void decrement() {
        c--;
    }

    public synchronized int value() {
        return c;
    }
}

查看编译后代码命令：

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javap -c SynchronizedCounter.class

编译后内容：

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Compiled from "SynchronizedCounter.java"
public class sy.SynchronizedCounter {
  public sy.SynchronizedCounter();
    Code:
       0: aload_0
       1: invokespecial #1                  // Method java/lang/Object."<init>":<>V
       4: aload_0
       5: iconst_0
       6: putfield      #7                  // Field c:I
       9: return

  public synchronized void increment();
    Code:
       0: aload_0
       1: dup
       2: getfield      #7                  // Field c:I
       5: iconst_1
       6: iadd
       7: putfield      #7                  // Field c:I
      10: return

  public synchronized void decrement();
    Code:
       0: aload_0
       1: dup
       2: getfield      #7                  // Field c:I
       5: iconst_1
       6: isub
       7: putfield      #7                  // Field c:I
      10: return

  public synchronized int value();
    Code:
       0: aload_0
       1: getfield      #7                  // Field c:I
       4: ireturn
}