将值添加到类型的ArrayList元素

Question

Here is what I have. I'm trying to add a name value to the ArrayList of type indexStruct and have no idea how to do that. Name is a String, any help would be great. Thanks!

import java.util.ArrayList;
public class Currentindex {


    public void indexedWords(String currentWord, ArrayList <Indexstruct> currentIndex){     
    int convoMax=currentIndex.size();
    int convoMin=0;
    int placeHolder;
    int strComp;
    //pull words to skip that appear frequently in a typical conversation


    while(convoMax>convoMin){           //binary search 
        placeHolder=(convoMin+convoMax)/2;
        strComp=currentWord.compareToIgnoreCase(currentIndex.get(placeHolder).Word);
        if(strComp==0){
        currentIndex.add(placeHolder, Word);  //<--Where problem occurs     
            break;
        }       
        else if(strComp<0){ 
        convoMax=placeHolder-1;     
        }   
        else{
        convoMin=placeHolder+1;
        }
    }
        //addterm(currentIndex);
        System.out.println(currentIndex);
    }
}

Answer 1

I'm trying to add a name value to the ArrayList of type indexStruct.

The specific ArrayList can only have elements added that are of type indexStruct . This means, either they are:

1. objects of class indexStruct.
2. objects of a class extending indexStruct.
3. objects of a class implementing an interface called indexStruct.

The only way you could insert your string, is if there is a string field within the indexStruct Object.

You would create such an object, and assign the name. Then add this object to the arraylist.

currentIndex.add(placeHolder, Word);

The problem with the call currentIndex.add(placeHolder, Word); //<--Where problem occurs currentIndex.add(placeHolder, Word); //<--Where problem occurs , is that the Word variable does not exist.

I am assuming that you compare the currentWord with the specific element at placeHolder, and then wish to re-insert the same Word Again when they are equal (ignoring case). This should work if you change your line to:

currentIndex.add(placeHolder, currentIndex.get(placeHolder));

You would essentially be entering another instance of the same indexStruct object at the position placeHolder .

Also, I'd suggest you look into iterators or enhanced for loops which are optimized for iterating over ArrayLists .

See:

• ArrayList.ListIterator(int index) vs ArrayList.get(int index)
• http://www.deknight.com/java/enhanced-for-loop-in-java-5-0.html

Answer 2

You are using

1. ArrayList: Array List which can store objects of Indexstruct.
2. And you are trying to store indexstruct.word (Probably a String as I guess).

You are getting issues because of the type of Indexstruct.word is not compatible with ArrayList.

Try this Add currentIndex.add(placeHolder, new Indexstruct(word)); OR alternatively set word to newly constructed Indexstruct object and then add that object.