JAVA Integer类型自加实例详解

public class IntegerTest {

  @Test
  public void test() {
    Integer a = 1;
    System.out.println(System.identityHashCode(a));
    a++;
    System.out.println(System.identityHashCode(a));
  }
}

public class IntegerTest {
  public void test() {
    Integer a = 1;
    a++;
  }
}

Compiled from "IntegerTest.java"
public class com.migoo.common.IntegerTest {
 public com.migoo.common.IntegerTest();
  Code:
    0: aload_0
    1: invokespecial #1         // Method java/lang/Object."<init>":()V
    4: return

 public void test();
  Code:
    0: iconst_1
    1: invokestatic #2         // Method java/lang/Integer.valueOf:(I)Ljava/lang/Integer;
    4: astore_1
    5: aload_1
    6: astore_2
    7: aload_1
    8: invokevirtual #3         // Method java/lang/Integer.intValue:()I
   11: iconst_1
   12: iadd
   13: invokestatic #2         // Method java/lang/Integer.valueOf:(I)Ljava/lang/Integer;
   16: dup
   17: astore_1
   18: astore_3
   19: aload_2
   20: pop
   21: return
}