Sorting a vector

Question

hi
all i am having problem with sorting a vector.I have a vector which contain Objects and each object has string values
Vector->Objects->String 1 string 2 string 3;
now i want to sort by string 2 but i also want to sort it by string 3 i means vector should be able to sort by string 2 and second preriority to string 3 and then string1.
How can i do this i am over loading the comparator class.
Collection.sort(vector, new vecComparetor());
public int compare(Object obj1, Object obj2) {
retrun obj1.compareTo(obj2);
}

Answer 1

If I guessed correctly your class is something like the following:
package mydomain;
public class MyClass{
     private String str1, str2, str3;
     public MyClass( String str1, String str2, String str3){
          this.str1 = str1;
          this.str2 = str2;
          this.str3 = str3;
     public String getStr1(){ return str1;}
     public String getStr2(){ return str2;}
     public String getStr3(){ return str3;}
     public String toString(){ return "(" + str1 + ", " + str2 + ", " + str3 + ")";}
}Now, your problem is: Order Vector of MyClass objects by str2, then by str1, then by str3.
So here it is your Comparator:
package utils;
import mydomain.MyClass;
import java.util.Comparator;
public class MyComparator implements Comparator{
     public int compare( Object o1, Object o2){
          int i = 0;
          return (i = ((MyClass)o1).getStr2().compareTo( ((MyClass)o2).getStr2())) != 0? i:
                ((i = ((MyClass)o1).getStr1().compareTo( ((MyClass)o2).getStr1())) != 0? i:
                ((i = ((MyClass)o1).getStr3().compareTo( ((MyClass)o2).getStr3())) != 0? i: 0));
}Try it out with this tester (cut and paste these three classes. They compile and run.):
package utils;
import mydomain.MyClass;
import java.util.Vector;
import java.util.Collections;
public class MyComparatorTest{
     public static void main( String[] args){
          Vector v = new Vector();
          for( char x = 'a'; x <= 'c'; x++){
               for( char y = 'a'; y <= 'c'; y++){
                    for( char z = 'a'; z <= 'c'; z++){
                         v.add( new MyClass( new Character( x).toString(), new Character( y).toString(), new Character( z).toString()));
          System.out.println( v);
          Collections.sort( v, new MyComparator());
          System.out.println( v);
}