java program doubt......

[abhilashm86]

here is just starting of code, where random numbers are genrated and then sorted and searched,
should i use methods here? the array a getting created via random generator is out of scope!! and i can't use it after for loop?
how to do this without calling methods and just finish in main....


public class sorta {
public static void main(String[] args) {
Random rand=new Random();
int []a;
for(int i=0;i<9;i++) {
a=new int [] {rand.nextInt()};
}

System.out.println("before sorting");
for(int j=0;j<a.length;j++) {
System.out.println(a[j]);
}
}

}

[exutable]

here is just starting of code, where random numbers are genrated and then sorted and searched,
should i use methods here? the array a getting created via random generator is out of scope!! and i can't use it after for loop?
how to do this without calling methods and just finish in main....


public class sorta {
public static void main(String[] args) {
Random rand=new Random();
int []a;
for(int i=0;i<9;i++) {
a=new int [] {rand.nextInt()};
}

System.out.println("before sorting");
for(int j=0;j<a.length;j++) {
System.out.println(a[j]);
}
}

}

Well I don't know if this is it, but you definitely need to make sure that the loop iterates through a.length-1 because a.length is out of the array's index. Remember that counting in programming starts at 0

[baizon]

Hi,
you will get a compiling error "The local variable a may not have been initialized line 13"

So you need to change it to...


public class sorta {
public static void main(String[] args) {
Random rand=new Random();
int []a = new int[9];
for(int i=0;i<9;i++) {
a[i]= rand.nextInt();
}

System.out.println("before sorting");
for(int j=0;j<a.length;j++) {
System.out.println(a[j]);
}
}
}
Now it will work fine.

[abhilashm86]

yes thanks baizon
can anyone tell how exactly to use sort function call in java? i tried and then used search function, but have a look at output, onr element is missing? I could'nt figure out the error..........
import java.util.Arrays;
import java.util.Random;
public class sorta {
public static void main(String[] args) {
Random rand=new Random();
int []a=new int[9];

for(int i=0;i<a.length-1;i++) {
a[i]=rand.nextInt() %10;
}


System.out.println("before sorting");
for(int j=0;j<a.length-1;j++) {
System.out.print(" " +a[j]+ " ");
}

Arrays.sort(a);

System.out.println("after sorting");
for(int j=0;j<a.length-1;j++) {
System.out.print(" " +a[j]+ " ");
}
int flag = 0;
int key=5,k = 0;
for(int j=0;j<a.length-1;j++) {
k=Arrays.binarySearch(a,key);
if(k==j)
{
System.out.println("key found at "+k+" position");
flag=1;
}
}
if(flag!=1)
{
System.out.println("key not found");
}
}
}



here is output

before sorting
-2 0 9 5 -9 2 0 3 after sorting
-9 -2 0 0 0 2 3 5 key found at 7 position
as you can see 9 is not shown in sorted array??

[Ragazzo]

The for-loop doesn't iterate to the last item because of -1 in there.

The correct form is:


for(int j=0;j<a.length;j++)

[baizon]

Yes, Ragazzo is right (and exutable was wrong). So you iterate from 0-a.length-1 which is 8, but you have 9 array positions.
That's tricky so always look out at this point ;)

Edit: So you have to change everywhere a.length-1 to a.length!



import java.util.Arrays;
import java.util.Random;

public class test {
public static void main(String[] args) {
Random rand=new Random();
int []a=new int[9];

for(int i=0;i<a.length;i++) {
a[i]=rand.nextInt() %10;
}


System.out.println("before sorting");
for(int j=0;j<a.length;j++) {
System.out.print(" " +a[j]+ " ");
}

Arrays.sort(a);

System.out.println("after sorting");
for(int j=0;j<a.length;j++) {
System.out.print(" " +a[j]+ " ");
}
int flag = 0;
int key=5,k = 0;
for(int j=0;j<a.length;j++) {
k=Arrays.binarySearch(a,key);
if(k==j)
{
System.out.println("key found at "+k+" position");
flag=1;
}
}
if(flag!=1)
{
System.out.println("key not found");
}
}

}




before sorting
2 0 5 7 -7 -7 0 -4 5 after sorting
-7 -7 -4 0 0 2 5 5 7 key found at 6 position

[exutable]

my bad, ****** up coach

[abhilashm86]

my bad, ****** up coach

whats that mean?? kinda din't get you!!