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Java me 从哈希表J2ME获取第一项_Java Me_Hashtable - Fatal编程技术网

Java me 从哈希表J2ME获取第一项

Java me 从哈希表J2ME获取第一项,java-me,hashtable,Java Me,Hashtable,我试图找到从至少包含5个元素的哈希表中获取第一项的方法。我有这个: Hashtable parkingSlots; parkingSlots = new Hashtable(); parkingSlots.put("P1", null); parkingSlots.put("P2", null); parkingSlots.put("P3", null); parkingSlots.put("P4", null); parkingSlots.put("P5", null); Enumer

我试图找到从至少包含5个元素的哈希表中获取第一项的方法。我有这个:

Hashtable parkingSlots;

parkingSlots = new Hashtable();

parkingSlots.put("P1", null);
parkingSlots.put("P2", null);
parkingSlots.put("P3", null);
parkingSlots.put("P4", null);
parkingSlots.put("P5", null);


Enumeration gPL = parkingSlots.Keys();

While( gPL.hasMoreElements()){

    String parkingNum = (String) gPL.nextElement();
    **// Here I've this result:  P1, P2, P3, P4, P5  but I want to get only the first item, in this case P1**

}

放一个
断点语句就在最后一个收尾方括号(
}
)之前。

如果您只需要一个,您可以将while替换为If,仅此而已

记住两件事:Hashtable没有定义的顺序,以及在块外定义parkingNum变量。。如果你以后想用的话

...
String parkingNum = null;
if( gPL.hasMoreElements()){
    parkingNum = (String) gPL.nextElement();
}
...