Please I need help with this, if I have an arraylist with elements [10,+,20,-,129]. I want to know how I can delete from behind the elements in the last index in the arraylist e.g removing 9 so that the array becomes [10,+,20,-,12]. Thanks
6 Answers
As its list of string elements, first take the last element and check whether the length of last element. If length is 1 then remove it, else trim one char from last.
// Adding element in list
list.add("1")
list.add("-");
list.add("23");
list.add("+");
list.add("123");
list.add("-");
// Size of List
int size = list.size();
// Getting Last element
String lastValue = list.get(size-1);
// check the length of last element
if(lastValue.length()<=1)
list.remove(size - 1);
else
list.set(size-1,lastValue.substring(0,lastValue.length()-1));
Hope it will solve the issue
Input : [1, -, 23, +, 123, -]
Output : [1, -, 23, +, 123]
1 Comment
Ferrybig
While this code snippet may solve the question, including an explanation really helps to improve the quality of your post. Remember that you are answering the question for readers in the future, and those people might not know the reasons for your code suggestion. - From review
I hope this may suites your needs:
String last = list.remove(list.size() - 1);
list.insert(last.substring(0,last.length() -1);
Disclaimer: As I saw the diversity of the elements in your example I assumed the list is a list of Strings.
Comments
List elements = Arrays.asList("10","+","20","-","144429");
String str = (String) elements.get(elements.size()-1); //get value of last element
str = str.substring(0, str.length()-1); //get all characters besides last one
elements.set(elements.size()-1, str); //replace last element in list
2 Comments
Okeme Christian
Code works fine for normal numbers, but not for operators like(+,-,)
Dariusz R.
For single character elements you receives empty String element of list. You can add
if statement to remove element from list if it consists of one character.Try get the item on the list, convert that item to string if it is not an array list of strings remove the digit you what by split or substring method then convert back to integer and add to the ArrayList. example send your Array list to the generate new List
public ArrayList<String> globalStrings;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
globalStrings = new ArrayList<>();
globalStrings.add("10");
globalStrings.add("+");
globalStrings.add("-");
globalStrings.add("129");
//Before
checklist(globalStrings);
globalStrings = getNewStrings(globalStrings);
//After
checklist(globalStrings);
}
getNewStrings returns a new ArrayList string with the last index item deleted by one
private ArrayList<String> getNewStrings(ArrayList<String> generateNew) {
String getString = generateNew.get(generateNew.size() - 1);
getString = getString.substring(0,(getString.length() - 1));
generateNew.remove(generateNew.size() - 1);
generateNew.add(getString);
return generateNew;
}
To check the list, you can use the method below
private void checklist(ArrayList<String > check) {
for(int count =0; count <check.size(); count ++) {
Log.e("TAG", "List " + check.get(count));
}
}
2 Comments
Okeme Christian
If the operation is repeated it should continue removing the last digit of the last item in the arraylist till the arraylist becomes empty
Franklyn
I just edited my post with codes example, try that to get your items deleted by one int.
Try Like this it may be work for you
ArrayList<String> arrayList = new ArrayList<>();
//add your data to this list
//suppose
// arrayList.add("10");
// arrayList.add("+");
// arrayList.add("20");
// arrayList.add("-");
// arrayList.add("129");
btnClick = (Button)findViewById(R.id.btnClick);
btnClick.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if(arrayList.size() > 0) {
String lastOne = arrayList.get(arrayList.size() - 1);
String newOne = removeLastChar(lastOne);
arrayList.remove(arrayList.size() - 1);
if (!newOne.equalsIgnoreCase("")) {
arrayList.add(arrayList.size(), newOne);
}
for (String item : arrayList) {
Log.d("TAG", item);
}
}
}
});
}
public String removeLastChar(String s) {
if (s == null || s.length() == 0) {
return s;
}
return s.substring(0, s.length()-1);
}
Comments
This is a simple program to solve your problem. You can add the null check conditions to make it better.
List<String> a= new ArrayList<>();
a.add("123");
a.add("856");
a.add("85");
a.add("785");
String trim = a.get(a.size()-1);
trim = trim.substring(0,trim.length()-1);
if(trim.equals("")){
a.remove(a.size()-1);
}
else{
a.set(a.size()-1,trim);
}
System.out.println(a);
output: [123, 856, 85, 78]
3 Comments
Okeme Christian
Code works fine for normal numbers, but not for operators like(+,-,)
sallu
it will , you should have a arraylist of type string.
sallu
edited the answer to remove if it is blank entry after removing single chars like +,-
ArrayListofString?[10, +, 20, -, 129]-->[10, +, 20, -, 12]-->[10, +, 20, -, 1]--> ???