how to concatenate two strings using for loop in java

The answer is: using '+' operator. Alternatively, you can use the String method String concat(String): http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#concat(java.lang.String).

The "using for loop" part simply makes no sense. Do with your loop whatever you need to, don't mix different things together. When you ask a "how to" question, you should not mix it with you understanding of "how" to do it.

—SA

Here your solution,,,

public static void main(String[] args) {
        String str1 = "Ajith ";
        String str2 = "Kp";
        int n1 = str1.length();
        int n2 = str2.length();
        char[] chr = new char[n1+n2];
        int ind = 0;
        for(int i=0;i<n1;i++)
        {
            chr[ind] = 0;
            chr[ind++] = str1.charAt(i);
        }
        for(int i=0;i<n2;i++)
        {
            chr[ind] = 0;
            chr[ind++] = str2.charAt(i);
        }
        String str = String.valueOf(chr);
        System.out.println(str);
    }