Java Community | Help. Code. Learn.•4d ago

Converting int array to byte array

I am attempting to convert an array of ints to a byte array to store in a file which will later be read and converted back into an int array. these are my conversion methods:

public static byte[] intArrayToByteArray(int[] intArr) {
    byte[] byteArr = new byte[intArr.length*4];
    for (int i = 0; i < intArr.length; i++) {
        int val = intArr[i];
        byteArr[(i*4)] = (byte) (val >> 24);
        byteArr[(i*4)+1] = (byte) (val >> 16);
        byteArr[(i*4)+2] = (byte) (val >> 8);
        byteArr[(i*4)+3] = (byte) (val);
    }
    return byteArr;
}
public static int[] byteArrayToIntArray(byte[] byteArr) {
    int[] intArr = new int[byteArr.length/4];
    for (int i = 0; i < intArr.length; i++) {
        intArr[i] = (byteArr[i*4] & 0xFF << 24) | (byteArr[(i*4)+1] & 0xFF << 16) | (byteArr[(i*4)+2] & 0xFF << 8) | (byteArr[(i*4)+3] & 0xFF);
    }
    return intArr;
}

public static byte[] intArrayToByteArray(int[] intArr) {
    byte[] byteArr = new byte[intArr.length*4];
    for (int i = 0; i < intArr.length; i++) {
        int val = intArr[i];
        byteArr[(i*4)] = (byte) (val >> 24);
        byteArr[(i*4)+1] = (byte) (val >> 16);
        byteArr[(i*4)+2] = (byte) (val >> 8);
        byteArr[(i*4)+3] = (byte) (val);
    }
    return byteArr;
}
public static int[] byteArrayToIntArray(byte[] byteArr) {
    int[] intArr = new int[byteArr.length/4];
    for (int i = 0; i < intArr.length; i++) {
        intArr[i] = (byteArr[i*4] & 0xFF << 24) | (byteArr[(i*4)+1] & 0xFF << 16) | (byteArr[(i*4)+2] & 0xFF << 8) | (byteArr[(i*4)+3] & 0xFF);
    }
    return intArr;
}

7 Replies

JavaBot•4d ago

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𝓐pothiconOP•4d ago

this is a test I did to see if my methods work

𝓐pothiconOP•4d ago

-2 billion is turning into -16 million not sure what i did wrong

dan1st•4d ago

try removing the & 0xFF or use parenthesis x & 0xFF << 24 is x & (0xFF << 24) but you want (x & 0xFF) << 24 same with the others

𝓐pothiconOP•4d ago

ah yep that was it thanks

JavaBot•4d ago

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