十进制转二进制，Java版

package experiment; import javax.swing.JOptionPane; public class Covert { public static void main(String[] args){ String numberString = JOptionPane.showInputDialog("Please enter a number!"); int number = Integer.parseInt(numberString); covertNumber(number); } private static void covertNumber(int number) { // if the number is a positive integer if ( number >= 0){ int i = 0; int sum = 0; do{ sum += ((number % 2)* (Math.pow(10, i))); number = (int) number/2; i++; }while(number != 0); for(int j = 0; j < (32 - i); j++){ System.out.print(0); } System.out.print(sum); } // if the number is negative else { number = number * (-1); int i = 0; int[] num = new int[32]; for(i = 0; i < 32; i ++){ num[i] = coverting(number % 2); number = (int) (number /2); } if(num[0] == 0) num[0] = 1; else{ int k = 0; do{ num[k] = coverting(num[k]); k++; }while(num[k] == 1); num[k] = 1; } for(int j = 31; j >= 0 ; j--){ System.out.print(num[j]); } } } private static int coverting(int num){ if(num == 1) num = 0; else num = 1; return num; } }