How to know if a given string is substring from another string in Java

Question

Hi I have to compute if a given string is substring of a bigger string. For example

String str = \"Hallo my world\";
String substr = \"my\"

<

Answer 1

You can use .substring(int beginIndex,int lastIndex) to check this program. Sample code goes as below:-

public class Test {

    public static void main(final String[] args) {
        System.out.println("Enter the first String");
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        try {
            String s1 = br.readLine();
            System.out.println("Enter the second String");
            String s2 = br.readLine();

            boolean result = isSubStr(s1, s2);
            if (result == true)
                System.out.println("The second String is substring of the first String");
            else
                System.out.println("The second String is not a substring of the first String");

        } catch (IOException e) {
            System.out.println("Exception Caught: " + e);
        }

    }

    public static boolean isSubStr(String st1, String s2) {

        boolean result = false;

        String tem_str = "";
        int len1 = st1.length();
        int i = 0;
        int j;

        while (i < len1) {
            j = i+1;
            while (j <=len1) {
                tem_str = st1.substring(i, j);
                if (tem_str.equalsIgnoreCase(s2)) {
                    result = true;
                    break;
                }
               j++;
            }

            i++;
        }
        return result;
    }
}

Answer 2

if (str.indexOf(substr) >= 0) {
    // do something
}

Answer 3

Go through this method. visit for tricky code

public static boolean isSubString(String s, String sub) {
    int count = 0;
    for (int i = 0; i < s.length(); i++) {
        if (s.charAt(i) == sub.charAt(count)) {
            count++;
        } else {
            i-=count;
            count = 0;
        }
        if (count == sub.length()) {
            return true;
        }

    }
    return false;
}

Answer 4

There is a contains() method! It was introduced in Java 1.5. If you are using an earlier version, then it's easy to replace it with this:

str.indexOf(substr) != -1

Answer 5

  String s = "AJAYkumarReddy";
    String sub = "kumar";
    int count = 0;
    for (int i = 0; i < s.length(); i++) {
        if (s.charAt(i) == sub.charAt(count)) {
            count++;
        } else {
            count = 0;
        }
        if (count == sub.length()) {
            System.out.println("Sub String");
            return;
        }

    }

Answer 6

public class StringIsSubString {

    public static void main(String[] args) {

        String s1 = "wel";
        String s2 = "12wlecome123";

        boolean isSubStr = isSubStr(s1,s2);
        System.out.println(isSubStr);
    }

    private static boolean isSubStr(String s1, String s2) {
        String s3 = "";
        int j = 0;

        if(s1.length() > s2.length()) {
            return false;
        } else if(s1.equals(s2)){
            return true;
        } else {
            for(int i=0; i<s1.length();i++) {
                for(; j<s2.length();j++) {
                    if(s1.charAt(i) == s2.charAt(j)) {
                        s3 = s3 + s1.charAt(i);
                        break;
                    }
                }
            }
            if(s3.equals(s1)) {
                return true;
            }
            return false;       
        }
    }
}