So basically, I've created a contains method and it prints out the correct output I need but after it does this it gives me an error:
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 3
at MethodTesting.main(MethodTesting.java:90)
Not sure why when it displays the output no worries? If anyone can give me an idea of what i'm doing wrong?? My code is below, i've tried adjusting the length to just length and length-1 as seen below. I've written the code in strings as opposed to char arrays however it wouldn't give me the right result. Hoping someone can shed some light perhaps?
//contains method
char[] st = "Hello World".toCharArray();
char[] substr = "llo".toCharArray();
for(int contains=0; contains<st.length-1; contains++){
if(substr[contains] == st[contains]){
for(int j=contains; j<st.length-1; j++){
if(st[j] == substr[j]){
}
else{
contains = -1;
}
}
}
System.out.println("CONTAINS");
System.out.println(contains);
}
Thanks, in advance!
Assuming that you are trying to search a substring of a string, this can be done in String.contains() method. If you are trying to implement the method yourself, then you have to change your code like this:
public static void main (String[] args)
{
char[] st = "Hello World".toCharArray();
char[] substr = "llo".toCharArray();
for(int contains = 0; contains < st.length - substr.length; contains++) {
int j;
for(j = 0; j < substr.length; j++) {
if(st[contains + j] != substr[j]) { // mismatch
break;
}
}
if (j == substr.length) // Every character in substr has been matched
System.out.println("Contains");
}
}
Your arrays aren't of equal length, yet in your second loop, you make an assumption that they are. contains can be a value higher than substr.length, and consequently, j will be, too.
To ensure that you don't step off the array while iterating, fix your bounds in your second loop.
Change for(int j=contains; j<st.length-1; j++) to for(int j=contains; j<substr.length; j++). This will ensure that your second loop is never executed if contains > substr.length, whereas it was executing as long as j < st.length()-1.
st array length and substr lengths are different.So the line
j<st.length-1; should be j<substr.length-1;
Related
This is the code I am working upon. I dont know where I am going wrong.
package mcdcpairwise;
import java.io.*;
import java.util.*;
public class Permutation
{
public static void main(String[] args)
{
String a="000";
String b="|&";
for (int i=0; i < a.length(); i++){
if (i % 2 != 0){
a = a.substring(0,i-1) + b.substring(0,i-1). + a.substring(i, a.length()) + b.substring(i, b.length());
System.out.println(a);
}
}
}
}
The error I am facing is:
Exception in thread "main" java.lang.StringIndexOutOfBoundsException:
String index out of range: -2 at
java.lang.String.substring(String.java:1967) at
mcdcpairwise.Permutation.main(Permutation.java:13)
The output should be :
0|0&0
It isn't clear from your question exactly what your "rules" are for processing this. However, your output seems to simply insert a character between each character of your source a string.
Instead of using a substring, create a separate StringBuilder to add individual characters to. The code below produces the output you are looking for:
String string = "000";
StringBuilder output = new StringBuilder();
for (int i = 0; i < string.length(); i++) {
// Get current character in the string
char c = string.charAt(i);
// Add the current character to the output
output.append(c);
// If more characters exist, add the pipe
if (i != string.length() - 1) {
output.append("|");
}
}
System.out.println(output.toString());
The right code should be a.substring(0,i).
You can use String.toCharArray to get a char[] from a String. That way we can iterate more easily both String using an index.
String a="000";
String b="|&";
char[] arrayA = a.toCharArray();
char[] arrayB = b.toCharArray();
Then, all we have to do is to merge two array (from Strings) taking one character from both. Adding two conditions (one per array) to prevent any ArrayIndexOutOfBOundsException, we can insure we will merge two arrays.
StringBuilder sb = new StringBuilder();
//Add a char from both array (until we reach on of the limit)
int i = 0;
while( i < arrayA.length && i < arrayB.length){
sb.append(arrayA[i]).append(arrayB[i]);
++i;
}
Then we just need to add the remaining characters using a for loop on both arrays. Only one of those loop will be triggered (or none) since at least one previous condition (i < arrayA.length && i < arrayB.length) is already false.
//Add the rest of `a` if any
for(int j = i; j < arrayA.length; ++j){
sb.append(arrayA[j]);
}
//Add the rest of `b` if any
for(int j = i; j < arrayB.length; ++j){
sb.append(arrayB[j]);
}
System.out.println(sb.toString());
0|0&0
Here’s a one line solution:
System.out.println((a + b).replaceAll("(?<=.)(?=.{" + (a.length() - 1) + "}(.))|.(?=.{0," + (b.length() - 1) + "}$)", "$1"));
This works with all combinations of non-blank starting strings.
See live demo.
first time posting here, I have this problem:
Write a static method named mostBowlsFull, to be added to the Bowl class, which is passed an array of Bowl objects, and returns true if a strict majority of the Bowls in the array are not empty. Thus if the array consists of 11 bowls and 6 are not empty, your method should return true, but if the array consists of 12 bowls and 6 (or fewer) are not empty, your method should return false.
we are given the class here:
https://cesd12.cs.umass.edu/owlj/servlet/ContentFileServer?ID=10778&ManuallyGraded=0&SecureID=2084635103&Server=owl-ijava31haverhillhs&TsActn=1422069785&datasrc=OwliJava31HaverhillHS&fileRequestID=4147
Not sure if it is accessible or if you must be logged on to the service :/
Anyways, this is the code I have
`public static boolean mostBowlsFull(Bowl bowls[]){
int count = 0;
for(int j = 0; j < bowls[].length(), j++){
if(bowls[j].getEmpty == true){
count++;
}
}
if(count > (bowls[].length()/2)){
return true;
}
}`
I am getting for feedback:
The system has detected compilation errors. This could be caused by:
Missing semicolon ; at the end of a statement.
Unclosed braces {}.
Unclosed parentheses ().
Unterminated string literals "".
Invalid method signature.
Missing return statement.
Redeclared variable or data member.
etc.
Any noticeable errors?
EDIT: Alright, so after review I have
public static boolean mostBowlsFull(Bowl bowls[]){
int count = 0;
for(int j = 0; j < bowls.length; j++){
if(bowls[j].getEmpty() == true){
count++;
}
}
if(count > (bowl.length/2)){
return true;
}
}
Still receiving the same message, although I do understand everything that was pointed out, thank you.
It will be easier and less time taking for you to use an IDE and resolve compilation errors.
I see two errors in your for loop:
for(int j = 0; j < bowls[].length(), j++){
use of comma instead of semicolon. for loop syntax is
for (initialization; termination; increment) {
statement(s)
}
Also length is a property for arrays and not a method. So use bowls.length instead of bowls[].length. Also not that you don't need [] while using length.
If you're trying to get the length of bowls, use bowls.length, not bowls[].length().
Also, in your for loop you need a semi-colon in between all three statements:
for(int j = 0; j < bowls.length; j++){ ... }
public static boolean mostBowlsFull(Bowl bowls[]){
int count = 0;
boolean ret=false;
for(int j = 0; j < bowls.length; j++){
if(bowls[j].getEmpty() == false){
count++;
}
}
if(count > (bowls.length/2)){
ret=true;
}
return ret;
}
I have been trying to execute this program which many will find a bit useless. Nevertheless I have been getting this error:Exception in thread "main" java.lang.StringIndexOutOfBoundsException while executing.this program is to find the number of vowels,consonants,special characters etc. and I recently got this error.Please help me. What is this error and how do I remove it from my code .Thanks in advance.
import java.io.*;
public class numberof {
public static void main(String args[])throws IOException{
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter string");
String str=br.readLine();
int vowel=0,consonant=0,upcase=0,locase=0,special=0,dig=0;
int l=str.length();
for(int in=1;in<=l;in++){ //This also is being displayed as an error
char c=str.charAt(in); //This is the error Line.
if(c>=65||c<=90||c>=97||c<=123){
if(c=='a'||c=='A'||c=='e'||c=='E'||c=='o'||c=='O'|c=='u'||c=='U'){
vowel++;
if(c>=65 && c<=90){
upcase++;
}
else{
locase++;
}
}
else{
consonant++;
if(c>=65 && c<=90){
upcase++;
}
else{
locase++;
}
}
}
else if(c>=48 && c<=57){
dig++;
}
else{
special++;
}
}
System.out.println(upcase+" "+locase+" "+vowel+" "+consonant+" "+dig+" "+special);
}
}
for(int in=1;in<=l;in++)
should be
for(int in=0;in<l;in++)
Array index starts from ZERO (in =0 assuming you want from first element)
EDIT:
l is length of String[], let us say 5 split into a[0], a[1], a[2], a[3], a[4].
If you observe, now you can start from 0 (or) 1 (or) 2, but max you can go upto a[4] only, when you use in <=, loop will check until a[5] which throws indexoutofBounds exception.
In your for loop, you're starting at index 1 and looping while smaller or equal to.
for (int in = 1; in <= l; in++) {}
This means you'll loop 2 more than you're supposed to. So it should be:
for (int in = 0; in < l; in++) {}
Array indexes are zero based, so it loops from 0 to length and not from 1 to length.
Another way of writing this is like this:
for(int i = 0; i < str.length(); i++) {}
Most java developers will find this easier to read.
Do you want to search for vowels in all string, starting from first character? use for(int in=0; in<l; in++)
Ok, my program in this specific section takes a line of data from a studentAnswer string array, the value of which would be something like TTFFTFTFTF. I am supposed to take this, and compare it against a key array, which might look like TFFFTFTFTF. A student takes a quiz, and my program calculates the points correct.
My intention is to use a separate points array to find the numeric grade for the student. The index of studentAnswer refers to a specific student. So studentAnswer[i] is TTFFTFTFTF. I use substrings to compare each individual T/F against the correct answer in key[], which would have a single T/F in each index. Then, if they are correct in their answer, I add a 1 to the correlating index in points[] and will later find the sum of points[] to find the numeric grade out of ten.
My problem here is that String origAns, used to define the student's original answer string, is getting a Java Error cannot find Symbol. I have tried placing the instantiation of origAns within each different for loop, but I can't get the program to work. Int i is meant to follow each specific student- I have four parallel arrays that will all log the student's ID number, numeric grade, letter grade, and original answers. So that is the intention of i, to go through each student. Then j should be used to go through each of these original student answer strings and compare it to the correct answer...
Logically, it makes sense to me where I would put it, but java doesn't agree. Please help me to understand this error!
for (int i = 0; i < studentAnswer.length; i++){
String origAns = studentAnswer[i];
for (int j = 0; j < key.length; j++){
if (origAns.substring[j] == key[j]){
//substring of index checked against same index of key
points[j] = 1;
}
if (origAns.substring[j] != key[j]){
points[j] = 0;
}
}
}
It sounds like you're trying to call the substring method - but you're trying to access it as if it were a field. So first change would be:
if (origAns.substring(j) == key[j])
Except that will be comparing string references instead of contents, so you might want:
if (origAns.substring(j).equals(key[j]))
Actually, I suspect you want charAt to get a single character - substring will return you a string with everything after the specified index:
if (origAns.charAt(j) == key[j])
... where key would be a char[] here.
You can also avoid doing the "opposite" comparison by using an else clause instead.
You should also indent your code more carefully, for readability. For example:
for (int i = 0; i < studentAnswer.length; i++) {
String origAns = studentAnswer[i];
for (int j = 0; j < key.length; j++) {
if (origAns.charAt(j) == key[j]) {
points[j] = 1;
} else {
points[j] = 0;
}
}
}
And now, you can change that to use a conditional expression instead of an if/else:
for (int i = 0; i < studentAnswer.length; i++) {
String origAns = studentAnswer[i];
for (int j = 0; j < key.length; j++) {
points[j] = origAns.charAt(j) == key[j] ? 1 : 0;
}
}
When you call a method in Java, you use parentheses () instead of brackets [].
Since substring is a method, you should call it like so
if (origAns.substring(j) == key[j])
A few other notes, you should use the equals method for comparisons (especially those comparisons involving Strings.)
if (origAns.substring(j).equals(key[j]))
Also, you should use charAt to extract a single character at some position in a string. substring(j) will return a string of characters starting at position j.
if (origAns.charAt(j).equals(key[j]))
Your explanation is very long and I have not read it from the beginning to end. But I can see at least one problem in your code:
if (origAns.substring[j] == key[j])
You are comparing strings using == instead of using method equals():
if (origAns.substring[j].equals(key[j]))
Substring is a function, not a member, of String objects. Check out the example at the top of this page:
http://docs.oracle.com/javase/6/docs/api/java/lang/String.html
Notice the use of parenthesis instead of brackets.
If you are using a String use charAt function
String studentAnswer = "TTFFTFTFTF";
for (int i = 0; i < studentAnswer.length(); i++)
{
char origAns = studentAnswer.charAt(i);
}
Else if you are using an char array then
char studentAnswer[] = "TTFFTFTFTF".toCharArray();
for (int i = 0; i < studentAnswer.length; i++){
char origAns = studentAnswer[i];
}
I want to write a program that prints words incrementally until a complete sentence appears. For example : I need to write (input), and output:
I
I need
I need to
I need to write.
Here is my code:
public static void main(String[] args) {
String sentence = "I need to write.";
int len = sentence.length();
int numSpace=0;
System.out.println(sentence);
System.out.println(len);
for(int k=0; k<len; k++){
if(sentence.charAt(k)!='\t')
continue;
numSpace++;
}
System.out.println("Found "+numSpace +"\t in the string.");
int n=1;
for (int m = 1; m <=3; m++) {
n=sentence.indexOf('\t',n-1);
System.out.println("ligne"+m+sentence.substring(0, n));
}
}
and this is what I get:
I need to write.
16
Found 0 in the string.
Exception in thread "main" java.lang.StringIndexOutOfBoundsException:
String index out of range: -1 at
java.lang.String.substring(String.java:1937) at
split1.Split1.main(Split1.java:36) Java Result: 1 BUILD SUCCESSFUL
(total time: 0 seconds)
I don't understand why numSpace doesn't count the occurrences of spaces, nor why I don't get the correct output (even if I replace numSpace by 3 for example).
You don't have a \t character, so indexOf(..) returns -1
You try a substring from 0 to -1 - fails
The solution is to check:
if (n > -1) {
System.out.prinltn(...);
}
Your loop looking for numSpace is incorrect. You are looking for a \t which is a tab character, of which there are none in the string.
Further, when you loop in the bottom, you get an exception because you are trying to parse by that same\t, which will again return no results. The value of n in n=sentence.indexOf('\t',n-1); is going to return -1 which means "there is not last index of what you are looking for". Then you try to get an actual substring with the value of -1 which is an invalid substring, so you get an exception.
You are mistaken by the concept of \t which is an escape sequence for a horizontal tab and not for a whitespace character (space). Searching for ' ' would do the trick and find the whitespaces in your sentence.
This looks like homework, so my answer is a hint.
Hint: read the javadoc for String.indexOf paying attention to what it says about the value returned when the string / character is not found.
(In fact - even if this is not formal homework, you are clearly a Java beginner. And beginners need to learn that the javadocs are the first place to look when using an unfamiliar method.)
The easiest way to solve this I guess would be to split the String first by using the function String.split. Something like this:
static void sentence(String snt) {
String[] split = snt.split(" ");
for (int i = 0; i < split.length; i++) {
for (int j = 0; j <= i; j++) {
if (i == 1 && j == 0) System.out.print(split[j]);
else System.out.printf(" %s", split[j]);
}
}
}
As other people pointed out. You are counting every characters except tabs(\t) as a space. You need to check for spaces by
if (sentence.charAt(k) == ' ')
\t represents a tab. To look for a space, just use ' '.
.indexOf() returns -1 if it can't find a character in the string. So we keep looping until .indexOf() returns -1.
Use of continue wasn't really needed here. We increment numSpaces when we encounter a space.
System.out.format is useful when we want to mix literal strings and variables. No ugly +s needed.
String sentence = "I need to write.";
int len = sentence.length();
int numSpace = 0;
for (int k = 0; k < len; k++) {
if (sentence.charAt(k) == ' ') {
numSpace++;
}
}
System.out.format("Found %s in the string.\n", numSpace);
int index = sentence.indexOf(' ');
while(index > -1) {
System.out.println(sentence.substring(0, index));
index = sentence.indexOf(' ', index + 1);
}
System.out.println(sentence);
}
Try this, it should pretty much do what you want. I figure you have already finished this so I just made the code real fast. Read the comments for the reasons behind the code.
public static void main(String[] args) {
String sentence = "I need to write.";
int len = sentence.length();
String[] broken = sentence.split(" "); //Doing this instead of the counting of characters is just easier...
/*
* The split method makes it where it populates the array based on either side of a " "
* (blank space) so at the array index of 0 would be 'I' at 1 would be "need", etc.
*/
boolean done = false;
int n = 0;
while (!done) { // While done is false do the below
for (int i = 0; i <= n; i++) { //This prints out the below however many times the count of 'n' is.
/*
* The reason behind this is so that it will print just 'I' the first time when
* 'n' is 0 (because it only prints once starting at 0, which is 'I') but when 'n' is
* 1 it goes through twice making it print 2 times ('I' then 'need") and so on and so
* forth.
*/
System.out.print(broken[i] + " ");
}
System.out.println(); // Since the above method is a print this puts an '\n' (enter) moving the next prints on the next line
n++; //Makes 'n' go up so that it is larger for the next go around
if (n == broken.length) { //the '.length' portion says how many indexes there are in the array broken
/* If you don't have this then the 'while' will go on forever. basically when 'n' hits
* the same number as the amount of words in the array it stops printing.
*/
done = true;
}
}
}