public?static?void?main(String[]?args)?{?
????????String?matcherStr?=?"This?is?the?first?Java";
????????matcherStr?+=?"\nAnd";
????????matcherStr?+=?"\nThis?is?the?second?Python";
????????Matcher?matcher?=?Pattern.compile("Java$",?Pattern.MULTILINE).matcher(matcherStr);
????????
????????int?i=0;
????????while(matcher.find()){
???????????i++;
????????}
????????System.out.println(i);
}

There is one match (i=1) for Java in the first line. This is mutiline, so the whole matcherStr is something like:

This is the first Java

And

This is the second Python

public?static?void?main(String[]?args)?{?
????????String?matcherStr?=?"This?is?the?first?Java";
????????matcherStr?+=?"\nAnd";
????????matcherStr?+=?"\nThis?is?the?second?Java";
????????Matcher?matcher?=?Pattern.compile("Java$",?Pattern.MULTILINE).matcher(matcherStr);
????????
????????int?i=0;
????????while(matcher.find()){
???????????i++;
????????}
????????System.out.println(i);
}

There are two matchs (i=2) for Java in the first line. This is mutiline, so the whole matcherStr is something like:

This is the first Java

And

This is the second Java

public?static?void?main(String[]?args)?{?
????????String?matcherStr?=?"This?is?the?first?Java";
????????matcherStr?+=?"\nAnd";
????????matcherStr?+=?"\nThis?is?the?second?Python";
????????Matcher?matcher?=?Pattern.compile("Java$").matcher(matcherStr);
????????
????????int?i=0;
????????while(matcher.find()){
???????????i++;
????????}
????????System.out.println(i);
}

There is no match?(i=0) for Java. This is not mutiline, so the whole matcherStr is something like:

This is the first Java\nAnd\nThis is the second Python

public?static?void?main(String[]?args)?{?
????????String?matcherStr?=?"This?is?the?first?Java";
????????matcherStr?+=?"\nAnd";
????????matcherStr?+=?"\nThis?is?the?second?Java";
????????Matcher?matcher?=?Pattern.compile("Java\\Z",?Pattern.MULTILINE).matcher(matcherStr);
????????
????????int?i=0;
????????while(matcher.find()){
???????????i++;
????????}
????????System.out.println(i);
}

There is one match?(i=1) for Java with multiline.? The same as without multiline.

In this case: If Pattern.compile("Java$",?Pattern.MULTILINE), there are two matches.

public?static?void?main(String[]?args)?{?
????????String?matcherStr?=?"This?is?the?first?Java";
????????matcherStr?+=?"\nAnd";
????????matcherStr?+=?"\nThis?is?the?second?Java";
????????Matcher?matcher?=?Pattern.compile("Java\\Z").matcher(matcherStr);
????????
????????int?i=0;
????????while(matcher.find()){
???????????i++;
????????}
????????System.out.println(i);
}

There is one match?(i=1) for Java without multiline.