字符串操作Java搜索subString序列

Question

We have a string declared as follows: String strString="This is a test statement to find a sub sequence of string";

There doesn't seem to be a method in String class that will search a sub sequence, like: Given String strString2="test ststement to find";

Here strString2 is a sub sequence of strString, Is there a way to find without character compare?

Answer 1

I believe you are looking for String#indexOf(String) . That will also give you the location in the string if it's found.

Answer 2

String.contains(CharSequence s)

Returns true if and only if this string contains the specified sequence of char values.

You can do something like this.

String strString="This is a test statement to find a sub sequence of string";
strString2="test ststement to find";
if(strString.contains(strString2)){
    //Do something. 
}

Answer 3

The condition to check existence of strString2 in strString is:

strString.indexOf(strString2) >= 0

or

strString.contains(strString2)

Answer 4

You could try this:

string1.contains(string2);`

Please note that it will throw a NullPointerException if string2 is null . You have to make sure that the string2 is not null before trying the comparison; the other situations should handle as you would expect. You can also use the toLowerCase() method along with contains() method if you would like to ignore case.

string1.toLowerCase().contains(string2.toLowerCase())

Also for older versions, you could use indexOf() method. If string2 is not in string1 , indexOf will give you -1 . Here also you must ensure beforehand that both Strings are not null though to avoid a NullPointerException .