一、十进制-->二进制

方法1：
System.out.println(Integer.toBinaryString(60));

方法2：
public static void toBin(int num){
    StringBuffer sb = new StringBuffer();
    while(num>0){
        sb.append(num%2);
        num = num / 2;
    }
    System.out.ptintln(sb.reverse());
}

方法3：(查表法；无局限性，可算负数)
public static void toBin(int num){
    char[] chs = {'0', '1'};
    char[] arr = new char[32];
    int pos = arr.length;
    while(num!=0){
        int temp = num & 1;
        arr[--pos] = chs[temp];
        num = num >>> 1;
    }
    for(int x=pos; x<arr.length; x++){
        System.out.println(arr[x]);
    }
}

二、十进制-->十六进制

方法1：
System.out.println(Integer.toHexString(60));

方法2：
public static void toHex(int num){
    StringBuffer sb = new StringBuffer();
    for(int x=0; x<8; x++){
        int temp = num & 15;
        if(temp>9){
          sb.append((char)(temp-10+'A'));
        }elae{
           sb.append(temp);
         {
        num = num >>> 4;
    }
    System.out.ptintln(sb.reverse());
}

方法3：
public static void toHex(int num){
    char[] chs = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
    char[] arr = new char[8];
    int pos = arr.length;
    while(num!=0){
        int temp = num & 15;
        arr[--pos] = chs[temp]);
        num = num >>> 4;
    }
    for(int x=pos; x<arr.length; x++){
        System.out.println(arr[x]);
    }
}

三、封装查表法实现进制转换：

/*
十进制转二进制
*/
public static void toBin(int num){
    trans(num,1,1);
}

/*
十进制转八进制
*/
public static void toOtc(int num){
    trans(num,7,3);
}

/*
十进制转十六进制
*/
public static void toHex(int num){
    trans(num,15,4);
}

/*
* num    要转进制的数字
* base   基数
* offset  偏移位数
*/
public static void trans(int num, int base, int offset){
    if(num==0){
        System.out.println(0);
        return;
    }
    char[] chs = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
    char[] arr = new char[32];
    int pos = arr.length;
    while(num!=0){
        int temp = num & base;
        arr[--pos] = chs[temp]);
        num = num >>> offset;
    }
    for(int x=pos; x<arr.length; x++){
        System.out.println(arr[x]);
    }

}