This question already has answers here:
Why does the foreach statement not change the element value?
(6 answers)
Java Modifying Elements in a foreach
(4 answers)
Java: Foreach loop not working as expected on int array? [duplicate]
(3 answers)
Closed 2 years ago.
Why won't this convert the string element as lowercase?
Given string input, converted into a string array. I want each word to be lowercase. However, when I debug, I notice the elements in my array are still varying in cases.
String[] words = paragraph.split(" "); //[how, to, do, in, java]
for(String word : words){
word = word.toLowerCase();
}
Because by doing toLowerCase(), you are instantiating a new String. So your word variable is no more a reference to an item of your array.
Either you add the result of the toLowerCase() to a new array or you loop with index :
for(i = 0;i < words.size();i++) {
words[i] = words[i].toLowerCase();
}
toLowerCase will return a new object, you have to store it.
You can use Java 8 to achieve it in one line:
Arrays.setAll(words, i -> words[i].toLowerCase());
You are not modifying your array instead you are assigning the lowercase string to the word instance
You can use the classic for loop and assign the lowercase value to the current index of the array
for en example, your for loop should look like
for(int i=0;i< words.length;i++){
words[i] = words[i].toLowerCase();
System.out.println(words[i]);
}
String objects are immutable by default. When you reassign something to string it creates a new object, hence the original String object in words array remain the same.
Related
This question already has answers here:
How do I declare and initialize an array in Java?
(31 answers)
Closed 1 year ago.
I'm wanting to store an a substring into a new array.
Here is my substring data = line.substring(i, i+1);
How do i do this? I have tried String data [] = line.substring(i, i+1) but not worked.
Thanks
.substring() does not return an array, it returns a String so passing it into an array won't work. You can split a String into a String[] array using the .split(String regex) method. The paramter is the delimiting regular expression, meaning if you did "Hello World".split(" "); (with space as the argument), the resulting array would be ["Hello", "World"]. If you want to split all of the characters into their own index of the array, just pass in an empty String "" as the argument of the split method (like line.split("")).
If your goal is to store the String in an array you can pass it in with a regular array declaration and assignment: String[] data = { line.substring(i, i + 1) }; or just make a new array and pass it into the desired index.
This question already has answers here:
Splitting String and put it on int array
(8 answers)
Closed 4 years ago.
If
String a="1,2,3,4,5"
I want to remove the commas in the string, and
change the string to an array, then
change every character of the array to integers, finally
apply any operation to the integers.
Is that possible?
I have this so far:
String input;
input = txtField.getText();
String[] a = new String[input.length()];
a = input.split(",");
for(int i=0;i==input.length();i++){
String c = a[i];
txtField.setText(String.valueOf(a));
}
it is, you could use a method which basically removes all commas(.split)so you get a String without commas, and later take that string and use a for loop to go through each char and parse to int.
This question already has answers here:
Java String array: is there a size of method?
(12 answers)
How to get first and last element in an array in java?
(7 answers)
Closed 4 years ago.
There is a string and I split it by whitespace and I want to get the last one.
String test = "Hey Hi Hello"; // Defining "test" String
test = test.split(" ")[2]; // Now "test" is "Hello"
System.out.print(test); // prints Hello
I should do this to get the last word of "test" String. But I know the length of the string. What should I do if I don't know the length of the String? What should I write between [ ] to get the last word?
For example when I get a data from an web page and I don't now the value is what.
test.split returns an array of Strings. Just save it somewhere instead of using it immediately and check its length.
String test = "Hey Hi Hello";
String[] words = test.split(" ");
test = words[words.length - 1];
System.out.print(test);
String[] temp = test.split(" "); //this will split whole string into array using white space.
test = temp[temp.length-1]; //gets the element at the last index of temp array
This question already has answers here:
Split string with dot as delimiter
(13 answers)
Closed 5 years ago.
I'm trying to fill an array of 2 elements with a element from another array, split by "." but it doesn't fill (for instance, the input is "83.105" and i need the first element to be "83" and the second "105"). When i try to get the 0 element from numberParts array it shows out of bounds exception. I'm really confused since this method is working on C# but not Java.
String[] inputNumbers = console.nextLine().split(" ");
String[] numberParts = inputNumbers[0].split(".");
System.out.println(numberParts[0]);
Dot (.) is a char that must be escaped in the split method.
why? because is a reserved character in regex
if not, splitting will return an empty array
String myString = "83.105";
String[] x = myString.split("\\.");
System.out.println(x[0]);
System.out.println(x[1]);
This question already has answers here:
Convert character to ASCII numeric value in java
(22 answers)
Closed 8 years ago.
I am trying to create a system that gets a string from the user and converts it to an integer. I want an integer representation for each letter, that way any string can be converted to an integer. I have tried putting each character of the string into an array, and then checking one by one for every letter. That method became to messy, so I was wondering if there was also a shorter way of doing this.
I want an integer representation for each letter
Use String to get Character Array by the use of "yourString".toCharArray();
Use ForEach loop to get int for every character.
for(char c:yourstring.trim().toCharArray())
{
int a=(int)c;
arrayList.add(a); //store integers to arrayList or array as you wish
}
Maybe the getNumericValue() method of Character is what you are after? You could use it in a loop.
If you want to convert a string to an integer you can try doing the following:
int c = Integer.parseInt("Your String");
For converting a letter to a string you can try the following:
String word = "abcd";
StringBuilder build = new StringBuilder();
for (char c : word.toCharArray()) {
build.append((char)(c - 'a' + 1));
}
So basically you subtract to find the integer value of the letter. NOTE: this only works for strings that are all in lower case. If you have letters in upper case you will have to convert them to lower case before applying the above.