java.lang.NullPointerException
at com.codegym.task.task09.task0930.Solution.main(Solution.java:18)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
It's not;( with the above output...
package com.codegym.task.task09.task0930;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.ArrayList;
/*
Task about algorithms
*/
public class Solution {
public static void main(String[] args) throws Exception {
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
ArrayList<String> list = new ArrayList<String>();
while (true) {
String s = reader.readLine();
if (s.isEmpty()) break;
list.add(s);
}
String[] array = list.toArray(new String[list.size()]);
sort(array);
for (String x : array) {
System.out.println(x);
}
}
public static void sort(String[] array) {
// write your code here
ArrayList<String> slist = new ArrayList<String>();
ArrayList<Integer> ilist = new ArrayList<Integer>();
ArrayList<Integer> sno = new ArrayList<Integer>();
ArrayList<Integer> ino = new ArrayList<Integer>();
for (int i=0; i<array.length; i++){
if (isNumber(array[i])){
ilist.add(Integer.parseInt(array[i]));
ino.add(i);
}else{
slist.add(array[i]);
sno.add(i);
}
}
for (int i=0; i<ilist.size(); i++){
for (int j=i+1; j<ilist.size(); j++){
if (ilist.get(i)<ilist.get(j)){
int a = ilist.get(i);
ilist.set(i, ilist.get(j));
ilist.set(j, a);
}
}
}
for (int i=0; i<slist.size(); i++){
for (int j=i+1; j<slist.size(); j++){
if (isGreaterThan(slist.get(j), slist.get(i))){
String a = slist.get(i);
slist.set(i, slist.get(j));
slist.set(j, a);
}
}
}
for (int i=0; i<ino.size(); i++){
array[ino.get(i)] = Integer.toString(ilist.get(i));
}
for (int i=0; i<sno.size(); i++){
array[sno.get(i)] = slist.get(i);
}
}
// String comparison method: 'a' is greater than 'b'
public static boolean isGreaterThan(String a, String b) {
return a.compareTo(b) > 0;
}
// Is the passed string a number?
public static boolean isNumber(String s) {
if (s.length() == 0) return false;
char[] chars = s.toCharArray();
for (int i = 0; i < chars.length; i++) {
char c = chars[i];
if ((i != 0 && c == '-') // The string contains a hyphen
|| (!Character.isDigit(c) && c != '-') // or is not a number and doesn't start with a hyphen
|| (i == 0 && c == '-' && chars.length == 1)) // or is a single hyphen
{
return false;
}
}
return true;
}
}