字符串常用操作整理

public class StrDeleteCh {

	public static void main(String[] args) {
		System.out.println(deleteCh("fgkikkii", "gi"));
	}

	/**
	 * 删除字符串高效的方法
	 * 比如 source = fgkikkii; removed = gi; 返回fkkk
	 * @param source  待删除字符串
	 * @param removed 要删掉的字符
	 * @return 
	 */
	public static String deleteCh(String source, String removed) {
		String result = "";
		boolean[] removeArray = new boolean[256];
		char[] removedchar = removed.toCharArray();
		for (int j = 0; j < removed.length(); j++) {
			removeArray[removedchar[j]] = true;
		}
		char[] sourcechar = source.toCharArray();
		int src = 0;
		do {
			if (!removeArray[sourcechar[src]]) {
				result += sourcechar[src];
			}
			src++;
		} while (src != source.length());
		return result;
	}//

}

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class StringTest {
	
	
	/**
	 * 1.如何反转字符串(输入abcd返回dcba)
	 * （也可以用堆栈来反转）
	 * @param str
	 * @return
	 */
	public static String testStrReverse(String str){
		StringBuffer sb = new StringBuffer(str);
		sb = sb.reverse();
		return sb.toString();
	}
	
	/**
	 * 2.如何判断一个字符串是否符合数字格式
	 * @param str
	 * @return
	 */
	public static boolean testStrIsNum(String str){
		Pattern p = Pattern.compile("\\d+");
		Matcher m = p.matcher(str);
		return m.matches();
	}
	
	//如何实现字符串转数字
	private static void testStrToNum(){
//		parseInt("0", 10) 返回 0
//		parseInt("473", 10) 返回 473
//		parseInt("-0", 10) 返回 0
//		parseInt("-FF", 16) 返回 -255
//		parseInt("1100110", 2) 返回 102
//		parseInt("2147483647", 10) 返回 2147483647
//		parseInt("-2147483648", 10) 返回 -2147483648
//		parseInt("2147483648", 10) 抛出 NumberFormatException
//		parseInt("99", 8)  抛出 NumberFormatException
//		parseInt("Kona", 10) 抛出 NumberFormatException
//		parseInt("Kona", 27) 返回 411787
		int ii = 999876;
		String s = "" + ii;  
		Integer i = Integer.parseInt(s);
		System.out.println(i +88);
		i = Integer.parseInt("a",16);
		System.out.println(i);
		i = Integer.parseInt("-ff",16);
		System.out.println(i);
	}
	
	//如何替换字符串中的子字符串
	private static void testStrReplace(){
		String str = "happy-new-year!";
		str = str.replace("-", "+");
		System.out.println(str);
	}
	
//	如何过滤字符串的空格
	private static void testStrReplace2(){
		String str = "  h a p p y n e w y e a r!  ";
//		str = str.trim(); //只能去掉前后空格
		str = str.replace(" ", "");
		System.out.println(str);
	}
	
	//如何实现字符串的切割和查找
	private static void testSplit(){
//		方法一
		String str = "happy-new-year!";
		String[] ss = str.split("-");
		for(String s : ss){
			System.out.println(s);
		}
		
//		方法二
		String str2 = "happy-new-year!";
//		查找indexOf
		String s2 = str2.substring(0, str2.indexOf("-"));
		System.out.println(s2);
		
//		方法三
		String str3 = "happy-new-year!";
		Pattern p = Pattern.compile("-");
		String[] ss3 = p.split(str3);
		for(String s : ss3){
			System.out.println(s);
		}
	}
	
	//@@如何实现字符串的查找(除indexOf外)
	private static void testStrFind(){
		String str3 = "happy-new-year!-happy-new-year!";
		String d = "new";
		Pattern p = Pattern.compile(d);
		Matcher m = p.matcher(str3);
		while (m.find()) {
			System.out.println(str3.substring(m.start(), m.end()));
			System.out.println(m.start() + " <> " + m.end() );
		}
	}
	
	//测试
	public static void main(String[] args) {
		System.out.println(testStrReverse("abcd123"));

		System.out.println(testStrIsNum("1232467"));
		
		testStrToNum();
		
		testStrReplace();
		
		testSplit();
		
		testStrFind();
		
	}

}