public class ReaplaceSpace {
static int i, j, k, count, length;
static String str;
static char[] array_original;
public static void main(String[]args){
BufferedReader br = new BufferedReader(
new InputStreamReader(System.in));
str = null;
System.out.println("please input a line string:");
try {
str = br.readLine();
} catch (IOException e) {
e.printStackTrace();
}
ReplaceString(str);
}
public static int OriginalSapceNum() {
char[] array_original = str.toCharArray();
length = array_original.length;
for(i = 0; i <= length;i++){
if(array_original[i] == ' '){
count++;
}
}
return count;
}
public static String ReplaceString(String str){
String tempString;
if(str == null || str.length() <= 0){
return null;
}else{
int count_replace= length + count*2;
char[] array_replace = new char[count_replace];
for(j = 0; j <= length; j++){
if((array_original[j] != ' ') && (k <= array_replace.length)){
array_replace[k] = array_original[j];
k++;
}else if((array_original[j] == ' ') && (k <= array_replace.length)){
array_replace[k] = '%';
array_replace[k+1] = '2';
array_replace[k+2] ='0';
k = k+3;
}
}
System.out.println(array_replace.toString());
tempString = array_replace.toString();
return tempString;
}
}
错误:Exception in thread "main" java.lang.NullPointerException
at ReaplaceSpace.ReplaceString(ReaplaceSpace.java:46)
at ReaplaceSpace.main(ReaplaceSpace.java:24)