java 求子字符串问题

[R-I-P]

如题：cd 是abcd 的子字符串；ac不是abcd的子字符串；
又如
isSubString("The", "The cat in the hat.") is true
isSubString("hat.", "The cat in the hat.") is true

现在我写了一个Search类

public class Search {
	//定义计数器
	private int i = 0 ;
	private int j = 0 ;
	//第一个字母
	private boolean first ;
	
	public boolean searchChar(String target,String source){
			for(;j<source.length() - target.length() + 1;j++){
				if(target.charAt(0) == source.charAt(j) ){
					first = true;
					break;
				}
			}
			
			if( first == true ){
				if(target.length() == 1){
					return true;
				}
				else{
					for(i=1,j++;i<target.length();i++,j++){
						if(target.charAt(i) != source.charAt(j)){
							return false;
						}
					}
					return true;
				}
			}
			else{
				return false;
			}
	}
}

但是对于isSubString("hat.", "The cat in the hat.") is true
hat 对于后者 因为有两个h，所以无法实现，那么我的代码该如何修改？

[bluemoby]

我写了一个，你可以参考一下

public class Test {

	public static boolean isSubString(String target,String source){
		//每次前进一个字符判断
		for(int i=0,j=source.length(),k=target.length();i+k<=j;i++){
			//取出一个子串
			String current=source.substring(i, i+k);
			//如果子串等于target则证明是子字符串
			if(current.equals(target)){
				return true;
			}
		}
		return false;
	}
	public static void main(String[] args) {
		System.out.println(isSubString("The", "The cat in the hat."));
		System.out.println(isSubString("hat.", "The cat in the hat."));
	}

}

而且String类中本身有子字符串的判断方法，contains()

[ZZZ5512536]

不能用string.contains(substring)?

[z2010490051]

public class Test { /** * @param args */ public static void main(String[] args) { new Test().match("hat", "the cat in the hat"); } public void match(String reg, String strs) { String[] str = strs.split(" "); for (String s : str) { if (s.matches(reg)) { System.out.println("true"); break; } } } }

[R-I-P]

问题已解决，只是使用了length（）和charAt（），下面是代码，欢迎测试

public class Search {
	//定义计数器
	private int i = 0 ;
	private int j = 0 ;
	//临时存储
	private int a = 0 ;
	private int b = 0 ;
	//循环计数器
	private int count = 0 ;
	
	public boolean searchChar(String target,String source){
			for(;j<source.length() - target.length() + 1;j++){
				if( target.charAt(0) == source.charAt(j)){
					a = i+1;
					b = j+1;
					
					
					while ( a < target.length()   &&   target.charAt(a) == source.charAt(b)){
						a++;
						b++;
						count++;
					}
					
					if(count == target.length()-1 ){
						return true;
					}
					else{
						continue;
					}
				}
			}
		return false;	
	}
}

[Mourinho]

public class Test {
	public static void main(String[] args) {
		Search search = new Search();
		System.out.println(search.isSubString("The", "The cat in the hat."));
		System.out.println(search.isSubString("hat.", "The cat in the hat."));
		System.out.println(search.isSubString("cat in th", "The cat in the hat."));
	}
}

class Search {
	public boolean isSubString(String str, String src) {
		int index = 0;
		while (index < src.length()) {
			int lastIndex = index;
			for (int i = 0; i < str.length();++i) {
				if (str.charAt(i) != src.charAt(index + i)) {
					index += (i + 1);
					break;
				}
			}
			if (lastIndex == index) {
				return true;
			}
		}
		return false;
	}
}

[beiouwolf]

话说 这是作业吗?要求不使用jdk本身方法? 如果不是的话... public boolean isSubString(String str,String src) { return src != null && src.indexOf(str) != -1; }