java interface using the comparator ArrayList Sort invalid

posts by wre_most2 edited 2012-10-18 20:12:33

I want to mRelaItems sort (code below)
According ShortcutInfo the hotseatOrder property, hotseatOrder is an integer
private ArrayList mRelaItems = new ArrayList ();
...
MyComparator myComparator = new MyComparator ();
Collections.sort (mRelaItems, myComparator);

class MyComparator implements Comparator {

@ Override
public int compare (ShortCutInfo object1, ShortCutInfo object2) {
/ / TODO Auto-generated method stub
if (object1.hotseatOrder return 1;

return 0;
}

}

But mRelaItems no change after sorting Sort invalid
Please advise
Thank you! !

And I wrote it in accordance with descending or ascending order of implementation?<-! Main posts under Banner (D4) -><-! Posts under the main text (D5) ->
Reply:
I debug your code a bit, no problem, you can achieve the sort, the result is descending, Here is the code I wrote

 import java.util.ArrayList; 
import java.util.Collections; 
import java.util.Comparator; 

public class Demo {

public static void main (String [] args) {
ArrayList  mRelaItems = new ArrayList  (); 
mRelaItems.add (new ShortCutInfo (1)); 
mRelaItems.add (new ShortCutInfo (12)); 
mRelaItems.add (new ShortCutInfo (3)); 
mRelaItems.add (new ShortCutInfo (7)); 
mRelaItems.add (new ShortCutInfo (2)); 

MyComparator myComparator = new MyComparator (); 
Collections.sort (mRelaItems, myComparator); 
for (ShortCutInfo c: mRelaItems) {
System.out.println ("======" + c.hotseatOrder + "======"); 
} 
} 
} 

class MyComparator implements Comparator  {
@ Override 
public int compare (ShortCutInfo object1, ShortCutInfo object2) {
if (object1.hotseatOrder return 1; 

return 0; 
} 

} 

Output:

====== 12 ======
====== 7 ======
====== 3 ======
====== 2 ======
====== 1 ======

Reply:

cited a floor reply:

I debug your code a bit, no problem, you can achieve the sort, the result is descending, the following is what I wrote code
Java code
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;

public class Demo {

public static void main (String [] ......

I still do not work here, ah

Reply:

reference to the second floor of the reply:

cited a floor reply:

I debug your code a bit, no problem, you can achieve the sort, the result is descending, Here is the code I wrote
Java code
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;

public class Demo {

public static v ......

Well, thank you!

Reply:
Support, refueling landlord
Reply:
How to solve ah
Reply:
Neighborhoods, my Comparator does not work ah ~ ~ do not know in the end is how children

 import java.util.ArrayList; 
import java.util.Collections; 
/ ** 
* Test class 
* / 
public class Test {

public static void main (String [] args) {
ArrayList  array = new ArrayList  (); 

DataEntity d1 = new DataEntity (1, 20.0); 
DataEntity d2 = new DataEntity (2, 10.0); 
DataEntity d3 = new DataEntity (3, 10.1); 
DataEntity d4 = new DataEntity (4, 40); 
DataEntity d5 = new DataEntity (5, 3.5); 
array.add (d1); 
array.add (d2); 
array.add (d3); 
array.add (d4); 
array.add (d5); 


SizeComparator cmp = new SizeComparator (); 
Collections.sort (array, cmp); 

for (DataEntity data: array) {
System.out.println (data); 
} 
} 
} 

import java.util.Comparator; 

/ ** 
* Achieve Comparator interface class 
* / 
public class SizeComparator implements Comparator  {

@ Override 
public int compare (DataEntity arg0, DataEntity arg1) {
if (arg0.getSize () <= arg1.getSize ()) {
return 1; 
} 
return 0; 
} 

} 

/ ** 
* Data entity classes 
* / 
public class DataEntity {
private int id; 
private double size; 

public DataEntity (int id, double size) {
this.id = id; 
this.size = size; 
} 

@ Override 
public String toString () {
return "id =" + id + "size =" + size; 
} 


public int getId () {
return id; 
} 

public void setId (int id) {
this.id = id; 
} 

public double getSize () {
return size; 
} 

public void setSize (double size) {
this.size = size; 
} 
} 

The resulting output is simply not sorted:
id = 1 size = 20.0
id = 2 size = 10.0
id = 3 size = 10.1
id = 4 size = 40.0
id = 5 size = 3.5

Reply:
I found the problem. . . Hard to force ah. . That program can not run in jdk1.7 in, Comparator does not work, but replaced like a 1.6. . Stumped is the 1.7 bug,
Reply:
Comparator 1.7 in the return value must be one pair of opposite number, such as 1 and -1, 0 and 1 can not be, because the sorting algorithm 1.7 timsort, http://baike.baidu.com/link?url=UCowuf65GHz3cWVf_d7t0QzYUCcwU0QUwserNTIrImlaTBvBAaVfywzppQ70DqWKzUu3dPqsF21k9IDpT8QPE_

There are strict requirements for the return value