我看到一段Java代碼約enum
:計算枚舉值
public enum Classname {
UIViewAutoresizingNone(0),
UIViewAutoresizingFlexibleLeftMargin(1 << 0),
UIViewAutoresizingFlexibleWidth(1 << 1),
UIViewAutoresizingFlexibleRightMargin(1 << 2),
UIViewAutoresizingFlexibleTopMargin(1 << 3),
UIViewAutoresizingFlexibleHeight(1 << 4),
UIViewAutoresizingFlexibleBottomMargin(1 << 5);
private int value;
// constructor
private Classname(int v) {
this.value = v;
}
public int value() {
return value;
}
}
System.out.println(Classname.UIViewAutoresizingFlexibleBottomMargin.value);
輸出:32
我想結果爲2至5。
的功率一般,如果是
i << j
什麼是快遞(我< < j)是什麼意思?我和j怎樣影響結果?有人可以指點我一個教程嗎?
相關:http://stackoverflow.com/q/16162290/1065197 – 2013-04-24 00:00:23
它在[tutorial](http://docs.oracle.com/javase/tutorial/java/nutsandbolts/op3.html)中有解釋。 – jlordo 2013-04-24 00:00:52