Effective Java 英文 第二版 读书笔记 Item 14:In public classes,use accessor methods,not public fields

本章主要分析 公开属性与私有属性提供公开get、set方法两种方式对比


// Degenerate classes like this should not be public!
class Point {
public double x;
public double y;



// Public class with exposed immutable fields - questionable
public final class Time {
private static final int HOURS_PER_DAY = 24;
private static final int MINUTES_PER_HOUR = 60;
public final int hour;
public final int minute;
public Time(int hour, int minute) {
if (hour < 0 || hour >= HOURS_PER_DAY)
throw new IllegalArgumentException("Hour: " + hour);
if (minute < 0 || minute >= MINUTES_PER_HOUR)
throw new IllegalArgumentException("Min: " + minute);
this.hour = hour;
this.minute = minute;
... // Remainder omitted

Certainly, the hard-liners are correct when it comes to public classes:

if a class is accessible outside its package, provide accessor methods, to preserve the

flexibility to change the class’s internal representation. If a public class exposes its
data fields, all hope of changing its representation is lost, as client code can be distributed
far and wide.



posted @ 2016-07-20 09:47  郁闷紫番薯  阅读(102)  评论(0编辑  收藏