如何将整数转换为整数?-HowtoconvertIntegertoint?

61  

As already written elsewhere:

已经写在其他地方:

• For Java 1.5 and later you don't need to do (almost) anything, it's done by the compiler.
• 对于Java 1.5以及以后的版本，您几乎不需要做任何事情，它是由编译器完成的。
• For Java 1.4 and before, use Integer.intValue() to convert from Integer to int.
• 对于Java 1.4和之前的版本，使用Integer. intvalue()将整数转换为int。

BUT as you wrote, an Integer can be null, so it's wise to check that before trying to convert to int (or risk getting a NullPointerException).

但是正如您所写的，一个整数可以是空的，所以在尝试转换为int(或冒获得NullPointerException的风险)之前检查它是明智的。

pstmt.setInt(1, (tempID != null ? tempID : 0));  // Java 1.5 or later

or

或

pstmt.setInt(1, (tempID != null ? tempID.intValue() : 0));  // any version, no autoboxing  

^* using a default of zero, could also do nothing, show a warning or ...

*使用默认值为零，也可以什么都不做，显示警告或……

I mostly prefer not using autoboxing (second sample line) so it's clear what I want to do.

我更喜欢不使用自动装箱(第二个示例行)，所以很清楚我想做什么。

12  

Since you say you're using Java 5, you can use setInt with an Integer due to autounboxing: pstmt.setInt(1, tempID) should work just fine. In earlier versions of Java, you would have had to call .intValue() yourself.

既然您说您正在使用Java 5，那么您可以使用setInt并使用一个整数，因为autounboxing: pstmt。setInt(1, tempID)应该可以正常工作。在早期的Java版本中，您必须亲自调用. intvalue()。

The opposite works as well... assigning an int to an Integer will automatically cause the int to be autoboxed using Integer.valueOf(int).

反之亦然……将int分配给一个整数将自动导致使用Integer.valueOf(int)对int进行自动装箱。

5  

Java converts Integer to int and back automatically (unless you are still with Java 1.4).

Java自动将整数转换为int并返回(除非您仍然使用Java 1.4)。

4  

Perhaps you have the compiler settings for your IDE set to Java 1.4 mode even if you are using a Java 5 JDK? Otherwise I agree with the other people who already mentioned autoboxing/unboxing.

也许您的IDE设置为Java 1.4模式，即使您使用的是Java 5 JDK?否则我同意那些已经提到自动装箱/拆箱的人。

3  

Another simple way would be:

另一个简单的方法是:

Integer i = new Integer("10");

if (i != null)
    int ip = Integer.parseInt(i.toString());