Hi
Why do you need that?
Try, for e.g.:
/**
*
* @author mihai
*/
public class PrintTwistedSequence {
public static void main(String[] args) {
for ( int i = 1 ; i < 7 ; i++ ){
boolean odd = (i%2 == 1);
int start = 20;
if ( odd ) start -= 2 * i - 1;
for ( int j = 0 ; j < start ; j++ )
System.out.print( ' ' ); // Print a space
// For odd numbers, like 1, 3, 5
if ( odd ) for ( int j = 1 ; j <= i ; j++ )
System.out.print(" " + j);
else // For even numbers, like 2, 4, 6
for ( int j = i ; j > 0 ; j-- )
System.out.print(" " + j);
System.out.println();
}
}
}
The output is then:
run:
1
2 1
1 2 3
4 3 2 1
1 2 3 4 5
6 5 4 3 2 1
BUILD SUCCESSFUL (total time: 0 seconds)
as expected (I think).
Hope it helps
Mihai
yaseen khan a écrit :
How to print this in java?
1
2 1
1 2 3
4 3 2 1
1 2 3 4 5
6 5 4 3 2 1
On Thu, Apr 29, 2010 at 7:26 AM, Kim Ching Koh <[email protected]
<mailto:[email protected]>> wrote:
Hi Mihai,
Thanks Mihai. The quick and dirty way always confused newbies
like me. Refer to your point on several small classess, we can
actually put them all in one class right? I tried this, and
(think) it works:
public class MyComparators implements Comparator {
public int compare(Object o1, Object o2) { // this code can be
inserted by NetBeans
throw new UnsupportedOperationException("Not supported yet.");
}
}
class MyIntegerComparator implements Comparator {
public int compare(Object o1, Object o2) {
int val1 = ((Integer)o1).intValue();
int val2 = ((Integer)o2).intValue();
return (val1<val2 ? -1 : (val1==val2 ? 0 : 1));
}
}
class MyStringComparator implements Comparator {
public int compare(Object o1, Object o2) {
String s1 = (String)o1;
String s2 = (String)o2;
int len1 = s1.length();
int len2 = s2.length();
int n = Math.min(len1, len2);
char v1[] = s1.toCharArray();
char v2[] = s2.toCharArray();
int pos = 0;
while (n-- != 0) {
char c1 = v1[pos];
char c2 = v2[pos];
if (c1 != c2) {
return c1 - c2;
}
pos++;
}
return len1 - len2;
}
}
On Thu, Apr 29, 2010 at 1:38 AM, Mihai DINCA <[email protected]
<mailto:[email protected]>> wrote:
Hi KC
Very nice observation, I confess always having some headaches
myself with this kind of code.
The Comparator (java.util.Comparator) is an interface. One can
define several comparators: one for String, another for
Integer and so on. This means several small classes, one per
comparator.
Instead of doing so, there is this dirty trick that allows to
have everything in a sole class.
This is the dirty trick. Let's say you have a simple (a small
number of methods) interface (or abstract class):
// MyInterface.java
public interface MyInterface {
public String sayHello(String name);
}
You can avoid writing the classes implementing this interface
and use ad-hoc inline code, such as:
// Test.java
public class Test {
public static void main(String[] args){
*MyInterface my1 = new MyInterface(){ // The
implementing class defined here**
public String
sayHello(String name){ return "Hello " + name; }
};
MyInterface my2 = new MyInterface(){ // Another
implementing class defined here
public String
sayHello(String name){ return "Bonjour " + name; }
};*
String name = "Bond, James Bond";
System.out.println( my1.sayHello(name));
System.out.println( my2.sayHello(name));
}
}
With the dirty trick, it is possible to write only two java
files (MyInterface.java and Test.java). Without it I had to
write two more classes (with all the redundant heading code).
It doesn't improve the code readability, but allows to write
less code (which is important for a sample exercise).
In the case of the Comparator, the idea was to create a sole
class file containing a "factory" and keeping together all the
comparators.
Hope it helps
mihai
kc a écrit :
Hi,
I am confused on how the Comparator interface is used in Execise 5.2
public static Comparator integerComparator() {
return new Comparator() {
public int compare(Object o1, Object o2) {
int val1 = ((Integer)o1).intValue();
int val2 = ((Integer)o2).intValue();
return (val1<val2 ? -1 : (val1==val2 ? 0 : 1));
}
};
}
instead of
public class MyComparator implements Comparator {
public int compare(Object o1, Object o2) {
int val1 = ((Integer)o1).intValue();
int val2 = ((Integer)o2).intValue();
return (val1<val2 ? -1 : (val1==val2 ? 0 : 1));
}
}
Regards
KC
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