Javaのシフト演算子について

/**
 *        <br/>
 * "<<"    :    0<br/>
 * ">>"       :       :   0，   1<br/>
 * ">>>"      :    0<br/>
 */
public class TestShift {
	public static void main(String[] args) {
		testLeftShift();
		testRightShift();
		testUnsignedRightShift();
	}

	/**
	 *   :    0
	 */
	public static void testLeftShift(){
		int num = -8;
		int shift = 2;
		leftShift(num, shift);
		leftShift(-num, shift);
		System.out.println("--------------");
	}
	/**
	 *   :    0
	 */
	public static void leftShift(int num, int shift){
		// num    shift 
		int r = num << shift;
		System.out.println("    : "+ num +" << "+shift);
		System.out.println("   :"+binary(num));
		System.out.println("   :"+binary(r));
		System.out.println("");
	}
	/**
	 *        :       
	 */
	public static void testRightShift(){
		int num = -8;
		int shift = 2;
		rightShift(num, shift);
		rightShift(-num, shift);
		System.out.println("--------------");
	}
	/**
	 *      :       
	 */
	public static void rightShift(int num, int shift){
		// num    shift 
		int r = num >> shift;
		System.out.println("(   )    : "+ num +" >> "+shift);
		System.out.println("   :"+binary(num));
		System.out.println("   :"+binary(r));
		System.out.println("");
	}
	/**
	 *     :    0
	 */
	public static void testUnsignedRightShift(){
		int num = -8;
		int shift = 2;
		unsignedRightShift(num, shift);
		unsignedRightShift(-num, shift);
		System.out.println("--------------");
	}
	/**
	 *   :    0
	 */
	public static void unsignedRightShift(int num, int shift){
		// num    shift 
		int r = num >>> shift;
		System.out.println("       : "+ num +" >>> "+shift);
		System.out.println("   :"+binary(num));
		System.out.println("   :"+binary(r));
		System.out.println("");
	}
	

	public static String binary(int  i){
		return alignRight(Integer.toBinaryString(i),32,'0');
	}
	/**
	 *     
	 * @param str      
	 * @param digit       
	 * @param addChar      
	 * @return
	 */
	public static String alignRight(String str, int digit, char addChar){
		str = String.valueOf(str);
		digit = digit > 0 ? digit : 0;
		
		StringBuilder builder = new StringBuilder(digit);
		builder.append(str);
		
		for (int len = str.length(); len < digit; len++) {
			builder.insert(0, addChar);
		}
		//
		return builder.toString();
	}
}