在java中铸造界面

我有两个独立的接口,一个“多语种”的文本选择要返回的语言,和第二个“理由”来证明返回的文本。 现在我需要加入他们,但我停留在“java.lang.ClassCastException”错误。 类图书在这里并不重要。 Data.length和FormattedInt.width对应线的宽度。 代码 :

public interface MultiLingual { static int ENG = 0; static int PL = 1; String get(int lang); int setLength(int length); } class Book implements MultiLingual { private String title; private String publisher; private String author; private int jezyk; public Book(String t, String a, String p, int y){ this(t, a, p, y, 1); } public Book(String t, String a, String p, int y, int lang){ title = t; author = a; publisher = p; jezyk = lang; } public String get(int lang){ jezyk = lang; return this.toString(); } public int setLength(int i){ return 0; } @Override public String toString(){ String dane; if (jezyk == ENG){ dane = "Author: "+this.author+"\n"+ "Title: "+this.title+"\n"+ "Publisher: "+this.publisher+"\n"; } else { dane = "Autor: "+this.author+"\n"+ "Tytul: "+this.title+"\n"+ "Wydawca: "+this.publisher+"\n"; } return dane; } } class Data implements MultiLingual { private int day; private int month; private int year; private int jezyk; private int length; public Data(int d, int m, int y){ this(d, m, y, 1); } public Data(int d, int m, int y, int lang){ day = d; month = m; year = y; jezyk = lang; } public String get(int lang){ jezyk = lang; return this.toString(); } public int setLength(int i){ length = i; return length; } @Override public String toString(){ String dane=""; String miesiac=""; String dzien=""; switch(month){ case 1: miesiac="January"; case 2: miesiac="February"; case 3: miesiac="March"; case 4: miesiac="April"; case 5: miesiac="May"; case 6: miesiac="June"; case 7: miesiac="July"; case 8: miesiac="August"; case 9: miesiac="September"; case 10: miesiac="October"; case 11: miesiac="November"; case 12: miesiac="December"; } if(day==1){ dzien="st"; } if(day==2 || day==22){ dzien="nd"; } if(day==3 || day==23){ dzien="rd"; } else{ dzien="th"; } if(jezyk==ENG){ dane =this.day+dzien+" of "+miesiac+" "+this.year; } else{ dane = this.day+"."+this.month+"."+this.year; } return dane; } } interface Justification { static int RIGHT=1; static int LEFT=2; static int CENTER=3; String justify(int just); } class FormattedInt implements Justification { private int liczba; private int width; private int wyrownanie; public FormattedInt(int s, int i){ liczba = s; width = i; wyrownanie = 2; } public String justify(int just){ wyrownanie = just; String wynik=""; String tekst = Integer.toString(liczba); int len = tekst.length(); int space_left=width - len; int space_right = space_left; int space_center_left = (width - len)/2; int space_center_right = width - len - space_center_left -1; String puste=""; if(wyrownanie == LEFT){ for(int i=0; i<space_right; i++){ puste = puste + " "; } wynik = tekst+puste; } else if(wyrownanie == RIGHT){ for(int i=0; i<space_left; i++){ puste = puste + " "; } wynik = puste+tekst; } else if(wyrownanie == CENTER){ for(int i=0; i<space_center_left; i++){ puste = puste + " "; } wynik = puste + tekst; puste = " "; for(int i=0; i< space_center_right; i++){ puste = puste + " "; } wynik = wynik + puste; } return wynik; } }

而测试代码,显示这件“(理由)不速之客[1]”这给了我的错误:

MultiLingual gatecrasher[]={ new Data(3,12,1998), new Data(10,6,1924,MultiLingual.ENG), new Book("Sekret","Rhonda Byrne", "Nowa proza",2007), new Book("Tuesdays with Morrie", "Mitch Albom", "Time Warner Books",2003, MultiLingual.ENG), }; gatecrasher[0].setLength(25); gatecrasher[1].setLength(25); Justification[] t={ new FormattedInt(345,25), (Justification)gatecrasher[1], (Justification)gatecrasher[0], new FormattedInt(-7,25) }; System.out.println(" 10 20 30"); System.out.println("123456789 123456789 123456789"); for(int i=0;i < t.length;i++) System.out.println(t[i].justify(Justification.RIGHT)+"<----\n");

--------------解决方案-------------

无论是数据或书执行的理由和多语言不继承Justiifcation所以它的预期,铸像(理由)不速之客[1]将失败。

你应该通过添加新的方法,改变你的理由类

String justify(Multilingual m);

然后,您可以通过电话证明资料或书籍的证明方法的书或数据的实例。

如果你不能改变你所写的,那么你可能要考虑

  1. 使用DynamicProxy API。 它采用反射所以可能你必须编写更多。
  2. 如果你知道如何映射证明()某种算法做执行与多语种的理由则可以考虑使用Facade模式。 它类似于DynamicProxy但更容易使用。
分类:java的 时间:2013-01-26 人气:0
本文关键词: java的,界面,铸造
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