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appendixB.java
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127 lines (92 loc) · 3.04 KB
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// A simple pattern matching demo.
import java.util.regex.*;
class RegExpr {
public static void main(String[] args) {
Pattern pat;
Matcher mat;
boolean found;
pat = Pattern.compile("Alpha");
mat = pat.matcher("Alpha");
found = mat.matches(); // check for a match
System.out.println("Testing Alpha against Alpha.");
if(found) System.out.println("Matches");
else System.out.println("No Match");
System.out.println();
System.out.println("Testing Alpha against Alpha Beta Gamma.");
mat = pat.matcher("Alpha Beta Gamma"); // create a new matcher
found = mat.matches(); // check for a match
if(found) System.out.println("Matches");
else System.out.println("No Match");
}
}
// -------------------------------------------------------
// Use find() to find a subsequence.
import java.util.regex.*;
class RegExpr2 {
public static void main(String[] args) {
Pattern pat = Pattern.compile("Alpha");
Matcher mat = pat.matcher("Alpha Beta Gamma");
System.out.println("Looking for Alpha in Alpha Beta Gamma.");
if(mat.find()) System.out.println("subsequence found");
else System.out.println("No Match");
}
}
// -------------------------------------------------------
// Use find() to find multiple subsequences.
import java.util.regex.*;
class RegExpr3 {
public static void main(String[] args) {
Pattern pat = Pattern.compile("Beta");
Matcher mat = pat.matcher("Alpha Beta Gamma Beta Theta");
while(mat.find()) {
System.out.println("Beta found at index " + mat.start());
}
}
}
// -------------------------------------------------------
// Use a quantifier.
import java.util.regex.*;
class RegExpr4 {
public static void main(String[] args) {
Pattern pat = Pattern.compile("W+");
Matcher mat = pat.matcher("W WW WWW");
while(mat.find())
System.out.println("Match: " + mat.group());
}
}
// -------------------------------------------------------
// Use wildcard and quantifier.
import java.util.regex.*;
class RegExpr5 {
public static void main(String[] args) {
Pattern pat = Pattern.compile("e.+d");
Matcher mat = pat.matcher("extend cup end table");
while(mat.find())
System.out.println("Match: " + mat.group());
}
}
// -------------------------------------------------------
// Use a character class.
import java.util.regex.*;
class RegExpr6 {
public static void main(String[] args) {
// Match lowercase words.
Pattern pat = Pattern.compile("[a-z]+");
Matcher mat = pat.matcher("this is a test.");
while(mat.find())
System.out.println("Match: " + mat.group());
}
}
// -------------------------------------------------------
// Use replaceAll().
import java.util.regex.*;
class RegExpr7 {
public static void main(String[] args) {
String str = "Jon Jonathan Frank Ken Todd";
Pattern pat = Pattern.compile("Jon.*? ");
Matcher mat = pat.matcher(str);
System.out.println("Original sequence: " + str);
str = mat.replaceAll("Eric ");
System.out.println("Modified sequence: " + str);
}
}