Question

I’ve searched for a while how to use logical operation AND in regular expressions in Java, and have failed.
I’ve tried to do as recommended in similar topic:

(?=match this expression)(?=match this too)(?=oh, and this)

and it doesn’t work. Even simple examples with ?= returns false:

String b = "aaadcd";
System.out.println(b.matches("(?=aa.*)"));

Also I’ve read that (expression X)(expression Y) should work like X AND Y, but it works like X OR Y.
What am I doing wrong?

Added:
Tried to add .* in the end. Still don’t work.
For a example:

[2-9]?[0-9]{5,9}||1[2-9][0-9]{1,2}||120[0-9]{1,1}||119[0-9] = X – return false if number is less than 1190

[0-9]{1,3}||1[0-0][0-9]{1,2}||11[0-8][0-9]{1,1}||119[0-2] = Y – return false if number is greater than 1992.

String a = "1189";
a.matches(X) // return false
a.mathes(Y)  // return true
a.matches((?=X)(?=Y).*) // return true, but should return false.

Added:
Yep, my regexp is not correct. My bad. The problem solved. Thank everyone very much!

Answer 1

I think what you need is (?=X)Y

• (?=X) matches X, without consuming it (zero-width)
• Y and matches Y

The main problem: X and Y are wrong, they should be (assuming 4 digits):

X: 119[0-9]|1[2-9][0-9]{2}|[2-9][0-9]{3}

• 1190-1199, or
• 1200-1999, or
• 2000-9999

Y: 1[0-8][0-9]{2}|19[0-8][0-9]|199[0-2]

• 1000-1899, or
• 1900-1980, or
• 1990-1992

Here a test code:

// X - return false if number is less than 1190
String X = "119[0-9]|1[2-9][0-9]{2}|[2-9][0-9]{3}"; 

// Y - return false if number is greater than 1992.
String Y = "1[0-8][0-9]{2}|19[0-8][0-9]|199[0-2]";

String pattern = "(?=" + X + ")" + Y;

String values = "1000 1100 1180 1189 1190 1191 1199 1200 1290 1900 1980 1989 " +
                "1990 1991 1992 1993 1999 2000 3000 2991 9999";
for (String string : values.split(" ")) {
    System.out.printf("\"%s\" %s%n", string, string.matches(pattern));
}