java中的| =是什么意思？

Question

这在这里的android通知中使用:

http://www.vogella.com/articles/AndroidNotifications/article.html#notificationmanager_configure

// Hide the notification after its selected
noti.flags |= Notification.FLAG_AUTO_CANCEL;

Answer 1

按位或与赋值.

int a = 6, b = 5;
a = a | b;
// is equivalent to
a |= b;

在像Android这样的系统中,将许多不同的布尔属性压缩为单个整数值通常是有意义的.值可以与之结合|并进行测试&.

// invented constants for example
public static final int HAS_BORDER = 1;   // in binary: 0b00000001
public static final int HAS_FRAME = 2;    //            0b00000010
public static final int HAS_TITLE = 4;    //            0b00000100

public void exampleMethod() {
  int flags = 0;                          //    flags = 0b00000000
  flags |= HAS_BORDER;                    //            0b00000001
  flags |= HAS_TITLE;                     //            0b00000101

  if ((flags & HAS_BORDER) != 0) {
    // do x
  }

  if ((flags & HAS_TITLE) != 0) {
    // do y
  }
}