public static void main(String a[]){
MyPatternReplace mpr = new MyPatternReplace();
System.out.println(mpr.replaceWithPattern("a b", "a c"));
System.out.println(mpr.replaceWithPattern("a b", "a c"));
System.out.println(mpr.replaceWithPattern("ab", "a c"));
System.out.println(mpr.replaceWithPattern("a c b", "a c"));
}
}