import java.text.*;public class StringAlign extends Format{public static final int JUST_LEFT='l'; //左對齊常量public static final int JUST_RIGHT='r'; //右對齊常量public static final int JUST_CENTER='c'; //居中常量PRivate int just; //當前的對其private int maxChars;public StringAlign(int maxChars,int just){switch (just) {case JUST_CENTER:case JUST_LEFT:case JUST_RIGHT:this.just=just;break;default:throw new IllegalArgumentException("invalid justification arg.");}if(maxChars<0){throw new IllegalArgumentException("必須是正數！");}this.maxChars=maxChars;}public StringBuffer format(Object obj,StringBuffer where,FieldPosition ignore){String s=(String)obj;String wanted=s.substring(0, Math.min(s.length(), maxChars));//如果沒有空間用于對齊，則返回最大行寬的內容if(wanted.length()>maxChars){where.append(wanted);}else switch (just) {case JUST_RIGHT:pad(where,maxChars-wanted.length());where.append(wanted);break;case JUST_LEFT:where.append(wanted);pad(where,maxChars-wanted.length());break;case JUST_CENTER:int startPos=where.length();pad(where,(maxChars-wanted.length())/2);where.append(wanted);pad(where,(maxChars-wanted.length())/2);//調整化整誤差pad(where,maxChars-(where.length()-startPos));break;

}return where;}protected final void pad(StringBuffer to,int howMany){for(int i=0;i<howMany;i++){to.append(' ');}}String format(String s){return format(s,new StringBuffer(),null).toString();}@Overridepublic Object parSEObject(String source, ParsePosition pos) {// TODO Auto-generated method stubreturn source;}

}