Java中的哈希表“未解決的編譯”

Question

這是我的課

package main;

import java.util.Hashtable;

public class Information {

    private final static String name = "Info Name";
    private final static String direccion = "direction street number";

    Hashtable<String,String> coordenates = new Hashtable<String,String>();
    coordenates.put("lat", "36.564565465");
    coordenates.put("lng", "64.584616511");

}

我從oracle文檔中學到了

This example creates a hashtable of numbers. It uses the names of the numbers as keys:

   Hashtable<String, Integer> numbers
     = new Hashtable<String, Integer>();
   numbers.put("one", 1);
   numbers.put("two", 2);
   numbers.put("three", 3);
To retrieve a number, use the following code:

   Integer n = numbers.get("two");
   if (n != null) {
     System.out.println("two = " + n);
   }

我的代碼有什么問題...

我在Windows 7 64位上使用Eclipse for Java EE Developers Java SE SDK 7（1.7）

謝謝！

Answer 1

您正在嘗試在方法，構造函數或static初始化程序的上下文之外執行代碼...

public class Information {

    private final static String name = "Info Name";
    private final static String direccion = "direction street number";

    Hashtable<String,String> coordenates = new Hashtable<String,String>();
    /**
      This belongs in a constructor or method
      coordenates.put("lat", "36.564565465");
      coordenates.put("lng", "64.584616511");
    **/

}

Answer 2

您正在嘗試在方法外調用hashtable.put（），則可以在構造函數內進行操作，我不確定您的要求是什么，但我想您可以避免hashtable的開銷並定義兩個字段lat和long

Answer 3

1.寫在主要功能上

public static void main(String args[]) {    
    Hashtable<String,String> coordenates = new Hashtable<String,String>();
    coordenates.put("lat", "36.564565465");
     coordenates.put("lng", "64.584616511");    
}

2.用構造函數編寫

    Information() {
      access setter of coordinates to put values
    }