UVA - 594 - One Little, Two Little, Three Little Endians

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringBuilder sb = new StringBuilder();
        String m = "";
        while ((m = br.readLine()) != null) {
            StringBuilder temp=null ;
            if(m.charAt(0)=='-'){
                String str=m.substring(1);
                str= Long.toBinaryString(Long.parseLong(str));
                temp = new StringBuilder(twoSComplement(str));
            }else{
                temp = new StringBuilder(Long.toString(Integer.parseInt(m), 2));
            }
            sb.append(m).append(" converts to ").append(operation(temp)).append("\n");
        }
        System.out.print(sb);
    }

    static String operation(StringBuilder temp) {
        while (temp.length() < 32) {
            temp.insert(0, "0");
        }
        StringBuilder ans = new StringBuilder();
        for (int i = 0; i < 8; i++) {
            ans.append(temp.charAt(i + 24));
        }
        for (int i = 0; i < 8; i++) {
            ans.append(temp.charAt(i + 16));
        }
        for (int i = 0; i < 8; i++) {
            ans.append(temp.charAt(i + 8));
        }
        for (int i = 0; i < 8; i++) {
            ans.append(temp.charAt(i));
        }
        return StringMan(ans);
    }

    static String StringMan(StringBuilder temp) {
        if (temp.charAt(0) == '1') {
            StringBuilder oneComplement = new StringBuilder();
            for (int i = 0; i < temp.length(); i++) {
                if (temp.charAt(i) == '0') {
                    oneComplement.append('1');
                } else {
                    oneComplement.append('0');
                } 
            }
            long h=Long.parseLong(oneComplement.toString(),2)+1;
            return "-"+h;
        }
        return Integer.parseInt(temp.toString(), 2) + "";
    }
   
    static String twoSComplement(String temp){
            StringBuilder oneComplement = new StringBuilder();
            while(temp.length()<32){
                temp='0'+temp;
            }
            for (int i = 0; i < temp.length(); i++) {
                if (temp.charAt(i) == '0') {
                    oneComplement.append('1');
                } else {
                    oneComplement.append('0');
                } 
            }
            long h=Long.parseLong(oneComplement.toString(),2)+1;
            return Long.toBinaryString(h);
    }
}