编写一个java程序计算若x=4,y=2,计算z值：

/*你的第二问和第三问怎么一样啊？需要改的话在case里改。不懂在问我*/
import java.util.Scanner;

public class Compute {
public static void main(String args[]) {
int x = 4, y = 2;
int z = 0, i = 0;

boolean bl = true;
System.out.println("x = 4, y =2输入序号1～7来计算如下答案");
System.out.println("(1) z=x&y (2) z=x|y (3) z=x|y (4) z=x>>y (5) z= ~ x (6) z= x<< y (7) z= x>>> y (8)退出");
Scanner in = new Scanner(System.in);
while (bl) {
String str = "输入有误";
try {
i = Integer.parseInt(in.next());
switch (i) {
case 1:
z = x & y;
str = "z = x & y = ";
break;
case 2:
z = x | y;
str = "z = x | y = ";
break;
case 3:
z = x | y;
str = "z = x | y = ";
break;
case 4:
z = x >> y;
str = "z = x >&g