疯狂java讲义第七章课后第2题答案

2.将字符串"ABCDEFG”中的"CD”截取出来；再将"B"、"F"截取出来。
（1）采用sunstring()+indexOf()

import java.util.*;
import java.io.*;
public class Test
{

	public static void main(String[] args) throws Exception
	{
		String str = "ABCDEFG";
		int start = str.indexOf("CD");
		int end = start + 2;
		//截取出CD
		System.out.println(str.substring(start,end));
		
		//截取出B
		start = str.indexOf("B");
		end = start +1;
		System.out.println(str.substring(start,end));
	
		//截取出F
		start = str.indexOf("F");
		end = start+1;
		System.out.println(str.substring(start,end));
	}
}

（2）采用正则表达式

import java.util.*;
import java.util.regex.*;
import java.io.*;
public class Test
{

	public static void main(String[] args) throws Exception
	{
		String str = "ABCDEFG";
		
		Matcher m = Pattern.compile("CD").matcher(str);
		while(m.find())
		{
			System.out.println(m.group());
		}
		
		Pattern pattern = Pattern.compile("B");
		Matcher m2 = pattern.matcher(str);
		while(m2.find())
		{
			System.out.println(m2.group());
		}

		Pattern pattern2 = Pattern.compile("F");
		Matcher m3 = pattern2.matcher(str);
		while(m3.find())
		{
			System.out.println(m3.group());
		}
	}
}