java - 为什么从非静态方法访问静态方法不好？

Question

Netbeans 告诉我从非静态方法访问静态方法是不好的。为什么这样不好？“访问静态方法 getInstance”是警告:

import java.util.Calendar;

public class Clock
{
    // Instance fields
    private Calendar time;

    /**
     * Constructor. Starts the clock at the current operating system time
     */
    public Clock()
    {
        System.out.println(getSystemTime());
    }

    private String getSystemTime()
    {
        return this.time.getInstance().get(Calendar.HOUR)+":"+
                this.time.getInstance().get(Calendar.MINUTE);
   }

Answer 1

您可能正在从实例而不是直接访问静态方法。尝试使用 Calendar.getInstance() 代替:

private String getSystemTime()
{
    return Calendar.getInstance().get(Calendar.HOUR)+":"+
           Calendar.getInstance().get(Calendar.MINUTE);
}