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add an element to int [] array in java


Question

Want to add or append elements to existing array

int[] series = {4,2};

now i want to update the series dynamically with new values i send..

like if i send 3 update series as int[] series = {4,2,3};

again if i send 4 update series as int[] series = {4,2,3,4};

again if i send 1 update series as int[] series = {4,2,3,4,1}; so on

How to do it????

I generate an integer every 5 minutes in some other function and want to send to update the int[] series array..

2013/04/09
1
50
4/9/2013 10:38:40 AM

Accepted Answer

The length of an array is immutable in java. This means you can't change the size of an array once you have created it. If you initialised it with 2 elements, its length is 2. You can however use a different collection.

List<Integer> myList = new ArrayList<Integer>();
myList.add(5);
myList.add(7);

And with a wrapper method

public void addMember(Integer x) {
    myList.add(x);
};
2013/04/09
80
4/9/2013 10:49:30 AM


If you are generating an integer every 5 minutes, better to use collection. You can always get array out of it, if required in your code.

Else define the array big enough to handle all your values at runtime (not preferred though.)

2013/04/09

Like others suggested you are better off using collection. If you however for some reason must stick to array then Apache Commons ArrayUtils may help:

int[] series = {4,2};
series = ArrayUtils.add(series, 3); // series is now {4,2,3}
series = ArrayUtils.add(series, 4); // series is now {4,2,3,4};

Note that the add method creates a new array, copies the given array and appends the new element at the end, which may have impact on performance.

2014/09/09

You'll need to create a new array if you want to add an index.

Try this:

public static void main(String[] args) {
    int[] series = new int[0];
    int x = 5;


    series = addInt(series, x);

    //print out the array with commas as delimiters
    System.out.print("New series: ");
    for (int i = 0; i < series.length; i++){
        if (i == series.length - 1){
            System.out.println(series[i]);
        }
        else{
            System.out.print(series[i] + ", ");
        }
    }
}

// here, create a method

public static int[] addInt(int [] series, int newInt){
    //create a new array with extra index
    int[] newSeries = new int[series.length + 1];

    //copy the integers from series to newSeries    
    for (int i = 0; i < series.length; i++){
        newSeries[i] = series[i];
    }
//add the new integer to the last index     
    newSeries[newSeries.length - 1] = newInt;



    return newSeries;

     }
2013/12/08

You could also try this.

public static int[] addOneIntToArray(int[] initialArray , int newValue) {

    int[] newArray = new int[initialArray.length + 1];
    for (int index = 0; index < initialArray.length; index++) {
        newArray[index] = initialArray[index];
    }

    newArray[newArray.length - 1] = newValue;
    return newArray;
}
2016/04/05

The size of an array can't be changed. If you want a bigger array you have to create a new array.

However, a better solution would be to use an (Array)List which can grow as you need it. The method ArrayList.toArray(T[] a) returns an array if you need to use an array in your application.

2013/04/09