palindrome.java

来自「一些Java的小的应用程序」· Java 代码 · 共 41 行

/**递归字符串判断是否回文*/
import java.io.BufferedReader;
import java.io.InputStreamReader;
public class Palindrome {
	public static void main(String args[]){
		try{BufferedReader input=new BufferedReader
			(new InputStreamReader(System.in));
		System.out.println("Enter a String :");
		String s=input.readLine();
		s=change(s);
		if(isPalindrome(s))System.out.println("The String that you have input is a palindrome");
		else System.out.println("It's not a palindrome!");
}catch(Exception e){
	System.out.println("ERROR!");
}}public static String change(String s){
	String s1="";
	for(int i=0;i<s.length();i++)
		if(isVaild(s.charAt(i)))s1+=s.charAt(i);
	return s1;
}public static boolean isPalindrome(String s){
	if(s.length()==1|s.length()==0)return true;
	else{
	if(s.charAt(0)==s.charAt(s.length()-1))
		return isPalindrome(s.substring(1, s.length()-1));
	else return false;}
}public static boolean isVaild(char c){
	boolean result;
	switch(c){
	case ' ':case '`':case '~':case '!':case '@':
	case '#':case'$':case'%':case'^':case'&':
	case'*':case'(':case')':case'-':case'_':
	case'+':case'=':case'|':case'\\':case'[':
	case']':case'{':case'}':case';':case':':
	case'\'':case'\"':case',':case'<':case'.':
	case'>':case'/':case'?':result=false;break;
	default:result=true;break;
		}return result;
}
	}