how to write code in java to convert plaintext into hexadecimal?

Question

String key="this is stack Overflow i am implementing aes algorithm"; //plaintext
String binary=stringToBinary(key); //convertion from plain text to binarydigits
String res[]=split_at(binary,8); //split binary digits into 8 bits
int c=0,r=0;

for(int i=0;i<res.length;i++) //convert each 8 bits into hexadecimal
{
    userKey[r][c]=binaryToHex(res[i]);
    c++;
    if(c==4)
    {
        c=0;
        r++;
        if(r==4)
        break;
    }
}
public static String[][] split_at(String str,int no)//method
{
    int i=0;
    int x=0;
    int l=str.length();
    String res[]=new String[(l/no)+1];
    int f=0;
    while(no<1){
        res[f]=str.substring(i,no);
        i=i+x;
        no=no+x;
        f++;
    }
    if(i<1){
        res[f]=str.substring(i,1);
    }
    return res;
}

I have tried this.but i dont know that it is correct or not.tell me is this correct process or not?if not then suggest me how to convert plaintext into hexa decimal.

Answer 1

Convert each character of the string to an int :

int character = (int) str.charAt(i);

Then get a hex representation of the int :

String hexString = Integer.toHexString(character);

Answer 2

get every character, parse to integer and convert it to hexadecimal

Example:

public static void main(String args[]) throws InterruptedException {
String key = "Hello world";// plaintext
byte[] x = key.getBytes();
StringBuilder sb = new StringBuilder();
for (int i = 0; i < x.length; i++) {
    int b = (int) x[i];
    sb.append(Integer.toHexString(b));
}
System.out.println(sb.toString());
}