java - 在字符串中找到一个整数

Question

I am trying to determine whether a specific digit exists in a String, and do something if so.

See code example:

String pass = "1457";
int i = 4, j=6;
if( /* pass contains i, which is true*/)
    // ..do something
if( /* pass contains j, which is false*/)
    // ..do something

The problem is I can't find the way to do this. I have tried -

pass.indexOf(""+i)!=-1
pass.indexOf((char)(i+48))!=-1
pass.contains(""+i)==true

any suggestions?

Answer 1

The problem is I can't find the way to do this. I have tried -any suggestions?

Code Example : (Execution)

Here we are creating a pattern and then matching it to the string.

import java.util.regex.Pattern;

public class PatternNumber {
    public static void main(String args[]) {
        String pass = "1457";
        int i = 4, j = 6;

        Pattern p1 = Pattern.compile(".*[4].*"); // creating a regular expression pattern
        Pattern p2 = Pattern.compile(".*[6].*");
        if (p1.matcher(pass).matches()) // if match found
            System.out.println("contains : " + i);
        if (p2.matcher(pass).matches())
            System.out.println("contains : " + j);

    }
}

Output :

One way to do this is by using Regular Expression :

A regular expression defines a search pattern for strings. The abbreviation for regular expression is regex. The search pattern can be anything from a simple character, a fixed string or a complex expression containing special characters describing the pattern. The pattern defined by the regex may match one or several times or not at all for a given string.

Regular expressions can be used to search, edit and manipulate text.

Answer 2

You can use Integer.toString() to convert integer to string and then find its index in string

Refer code snippet below:-

    String pass = "1457";
    int i = 4, j = 6;
    int index = pass.indexOf(Integer.toString(i));
    if (index > -1) // index of i is 1
    {
       //do something
    }
    index = pass.indexOf(Integer.toString(j));
    if(index < 0) // index of j is -1
    {
        //do something
    }

Answer 3

\n

pass.chars().anyMatch(c -> c == Integer.toString(i).charAt(0))