假设您编译以下两个类。第一个类表示客户端;第二个类是库类。
public class Test{
public static void main(String[] args) {
System.out.println(Lib.FIRST + " " +
Lib.SECOND + " " +
Lib.THIRD);
}
}
public class Lib{
private Lib() { }; // Uninstantiable
public static final String FIRST = "the";
public static final String SECOND = null;
public static final String THIRD = "set";
}
输出:
{空集}
现在假设您修改库类如下并重新编译它但不编译客户端程序:
public class Lib{
private Lib() { }; // Uninstantiable
public static final String FIRST = "physics";
public static final String SECOND = "chemistry";
public static final String THIRD = "biology";
}
打印:
{化学实验套装}
为什么SECOND
值发生了变化,但FIRST
或THIRD
没有变化?