[JAVA100例] 005 - 雜湊表與列舉器

範例展示 Hashtable 儲存角色與權限代碼對應關係，並實作增刪改查與列舉輸出功能。

public class RoleRight {
    private static Hashtable rightList = new Hashtable();

    public void init() {
        String[] accRoleList = {"admin","satrap","manager","user","guest"};
        String[] rightCodeList = {"10001","10011","10021","20011","24011"};
        for (int i = 0; i < accRoleList.length; i++)
            rightList.put(accRoleList[i], rightCodeList[i]);
    }

    public String getRight(String accRole) {
        if (rightList.containsKey(accRole))
            return (String) rightList.get(accRole);
        else
            return null;
    }

    public void insert(String accRole, String rightCode) {
        rightList.put(accRole, rightCode);
    }

    public void delete(String accRole) {
        if (rightList.containsKey(accRole))
            rightList.remove(accRole);
    }

    public void update(String accRole, String rightCode) {
        this.insert(accRole, rightCode);
    }

    public void print() {
        Enumeration RLKey = rightList.keys();
        while (RLKey.hasMoreElements()) {
            String accRole = RLKey.nextElement().toString();
            print(accRole + "=" + this.getRight(accRole));
        }
    }

    public void print(Object oPara) { System.out.println(oPara); }

    public static void main(String[] args) {
        RoleRight RR = new RoleRight();
        RR.init();
        RR.print();
        RR.print("___________________________");
        RR.insert("presider", "10110");
        RR.print();
        RR.print("___________________________");
        RR.update("presider", "10100");
        RR.print();
        RR.print("___________________________");
        RR.delete("presider");
        RR.print();
    }
}

執行結果依序顯示：初始資料、新增 presider、修改 presider、刪除 presider 後的雜湊表內容。展現 Hashtable 基本操作與 Enumeration 遍歷鍵值。