java十进制转二进制

• Integer.toBinaryString
• 移位操作 >>>1 & 1
• 倒叙取余

public class HexConvert {
    public static void main(String[] args) {
        // 二进制
        // 1. API函数
        int n = 10;
        // 1010
        System.out.println(Integer.toBinaryString(n));

        // 2. 移位
        //binaryString(10) = 00000000000000000000000000001010
        System.out.println(binaryString(n).substring(binaryString(n).indexOf("1")));

        // 3. 倒排取余
        System.out.println(mod(n));
    }

    private static String binaryString(int n) {
        StringBuilder sb = new StringBuilder();
        for (int i = 31; i >= 0; i--) {
            sb.append(n >>> i & 1);
        }
        return sb.toString();
    }

    private static String mod(int n) {
        StringBuilder stringBuilder = new StringBuilder();
        while(n / 2 != 0) {
            stringBuilder.append(Math.floorMod(n, 2));
            n = n / 2;
        }
        stringBuilder.append(Math.floorMod(n, 2));
        return stringBuilder.reverse().toString();
    }
}