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我正在尝试创建一种格式化十六进制字符串并将字符串分解为每 2 个字符等于一个字节的方法。我想要一个三个字节数组，例如字符串是“012254”，然后是“01”、“22”、“54”。我已经创建了这些方法，但是我得到了一个“NumberFormatException”，说 Invalid int：“”。任何人都可以看看我的代码并查看 logcat，看看我能做些什么来解决这个问题。先感谢您。

这是代码：

/*
 * Converts a set of hex digits into an array of 8-bit binary bytes.
 * Stops at the first non-hex character if before the end of the string.
 * Hex bytes are assumed to be pairs of digits i.e. least significant byte (LSB) -> most significant byte (MSB) with most significant nibble first.
 * e.g. for a string: "F20C345A" will convert to values F2,0C,34,5A.
 * Adds zeroes to the end of the string to make last digits up to the length for a byte.
 */
public byte[] toByteArray(String hexString)
{   
    int offSet = 0;
    int hexLength = 0;
    int bytes = 0;
    String byteString = "";
    byte[] byteArray;

    hexLength = hexSequenceLength(hexString); // Check for hex sequence.
    hexString = hexString.substring(0, hexLength); // Ignore anything after hex sequence.

    bytes = hexLength / CHARSPERBYTE; // Calculate how many words are represented by the string.

    int rem = hexLength % CHARSPERBYTE;

    if(rem != 0)
    {
        /*
         * Hex string is too short.
         * Add padding zeroes to fill up to boundary of a complete word.
         */
        int paddingZeroes = CHARSPERBYTE - rem;

        if((paddingZeroes & (int)0x01) != 0)
        {
            /*
             * Odd number of padding zeroes.
             * This means that the first zero must be inserted before the last digit to keep it the least significant nibble (4-bit).
             */
            hexString = new StringBuilder(hexString).insert(hexLength-1, "0").toString();

            paddingZeroes--;
        }

        /* Add zeroes to the end of the string so that MSB's of last value will be zero. */
        for(int i=0; i<paddingZeroes; i++)
        {
            hexString += "0";
        }

        /* Recalculate length. */
        hexLength = hexSequenceLength(hexString);
        bytes = hexLength / CHARSPERBYTE;
    }

    if(bytes > 0)
    {
        byteArray = new byte[bytes]; // Set up array to receive these values.

        for(int i=0; i<bytes; i++)
        {
            byteString = hexSubString(hexString, offSet, CHARSPERBYTE, false); // Isolate digits for a single byte.

            byteArray[i] = (byte)Integer.parseInt(byteString, 16); // Parse value into binary data array.

            offSet += CHARSPERBYTE; // Set up for next word hex.    
        }

        byte subSystem = byteArray[0];
        byte highLevel = byteArray[1];
        byte lowLevel = byteArray[2];
        String bytesValue = new String(byteArray);

        System.out.println("Byte array size: " + byteArray.length);
        System.out.println("Byte 1: " + subSystem);
        System.out.println("Byte 2: " + highLevel);
        System.out.println("Byte 3: " + lowLevel);
        System.out.println("Byte array value: " + bytesValue);
        // TODO: Need to get the actual value of the bytes, the result just returns 16.
    }
    else
    {
        byteArray = new byte[0]; // No hex data.

        //throw new HexException();
    }

    return byteArray;
}

/*
 * Isolates a HEX value sub-string from the given HEX character string from its start index and character length.
 * Includes option to re-order digit pairs to change the order of significance of bytes in a HEX number.
 */
private String hexSubString(String src, int index, int length, boolean reverse)
{
    int hexNumbers = length / CHARSPERBYTE;
    String[] hexNumber = new String[hexNumbers];
    int numberIndex = index;
    String hexSubString = "";

    for(int i=0; i<hexNumbers; i++)
    {   
        hexNumber[i] = src.substring(numberIndex, CHARSPERBYTE+2);
        numberIndex += CHARSPERBYTE;

        if(numberIndex > src.length())
        {
            break;
        }
    }

    if(reverse == false)
    {
        for(int i=0; i<hexNumbers; i++)
        {
            hexSubString += hexNumber[i];
        }
    }
    else
    {
        // Reverse order to make MSB -> LSB.
        for(int i=hexNumbers; i>0; i--)
        {
            hexSubString += hexNumber[i-1];
        }
    }

    return hexSubString;
}

/*
 * Gets the number of consecutive hex characters from start of string.
 */
private int hexSequenceLength(String hexString)
{
    int length = 0;

    char[] charArray = hexString.toCharArray();

    for(char c : charArray)
    {
        if(hexChecker(c))
        {
            length++;
        }
        else
        {
            break;
        }   
    }

    return length;
}

/*
 * Checks if character is valid against HEX values.
 */
private boolean hexChecker(char c)
{
    String hexValues = "0123456789abcdefABCDEF";

    if(hexValues.indexOf(c) > -1 == true)
    {
        System.out.println("It worked!");
    }
    else
    {
        System.out.println("It did not work!");
    }

    return hexValues.indexOf(c) > -1;
}

这是logcat：

10-07 11:53:11.420: E/AndroidRuntime(4440): FATAL EXCEPTION: main
10-07 11:53:11.420: E/AndroidRuntime(4440): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.mobileapplicationretry/com.example.mobileapplicationretry.MainActivity}: java.lang.NumberFormatException: Invalid int: ""
10-07 11:53:11.420: E/AndroidRuntime(4440):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2211)
10-07 11:53:11.420: E/AndroidRuntime(4440):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
10-07 11:53:11.420: E/AndroidRuntime(4440):     at android.app.ActivityThread.access$600(ActivityThread.java:141)
10-07 11:53:11.420: E/AndroidRuntime(4440):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
10-07 11:53:11.420: E/AndroidRuntime(4440):     at android.os.Handler.dispatchMessage(Handler.java:99)
10-07 11:53:11.420: E/AndroidRuntime(4440):     at android.os.Looper.loop(Looper.java:137)
10-07 11:53:11.420: E/AndroidRuntime(4440):     at android.app.ActivityThread.main(ActivityThread.java:5103)
10-07 11:53:11.420: E/AndroidRuntime(4440):     at java.lang.reflect.Method.invokeNative(Native Method)
10-07 11:53:11.420: E/AndroidRuntime(4440):     at java.lang.reflect.Method.invoke(Method.java:525)
10-07 11:53:11.420: E/AndroidRuntime(4440):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
10-07 11:53:11.420: E/AndroidRuntime(4440):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
10-07 11:53:11.420: E/AndroidRuntime(4440):     at dalvik.system.NativeStart.main(Native Method)
10-07 11:53:11.420: E/AndroidRuntime(4440): Caused by: java.lang.NumberFormatException: Invalid int: ""
10-07 11:53:11.420: E/AndroidRuntime(4440):     at java.lang.Integer.invalidInt(Integer.java:138)
10-07 11:53:11.420: E/AndroidRuntime(4440):     at java.lang.Integer.parseInt(Integer.java:359)
10-07 11:53:11.420: E/AndroidRuntime(4440):     at com.example.mobileapplicationretry.devicedescription.HexFunctions.toByteArray(HexFunctions.java:73)
10-07 11:53:11.420: E/AndroidRuntime(4440):     at com.example.mobileapplicationretry.devicedescription.DeviceValues.setUpValues(DeviceValues.java:76)
10-07 11:53:11.420: E/AndroidRuntime(4440):     at com.example.mobileapplicationretry.devicedescription.DeviceDescriptionDataSet.setUpDataSet(DeviceDescriptionDataSet.java:239)
10-07 11:53:11.420: E/AndroidRuntime(4440):     at com.example.mobileapplicationretry.MainActivity.onCreate(MainActivity.java:59)
10-07 11:53:11.420: E/AndroidRuntime(4440):     at android.app.Activity.performCreate(Activity.java:5133)
10-07 11:53:11.420: E/AndroidRuntime(4440):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
10-07 11:53:11.420: E/AndroidRuntime(4440):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2175)
10-07 11:53:11.420: E/AndroidRuntime(4440):     ... 11 more
4

2 回答 2

1

为什么不使用现有的类来做到这一点？

String myHexStr = "AB1257";
int hexInt = Integer.parseInt(myHexStr, 16);
ByteBuffer buffer = ByteBuffer.allocate(4);
buffer.putInt(hexInt);
byte[] result = buffer.array();

如果要创建一个 3 的数组，只需将结果数组复制到一个新的更小的数组。您唯一需要弄清楚的是要丢弃哪个字节：第一个字节（MSB）或最后一个字节（LSB）：

byte[] threeByteArray = new byte[3];

int start = useMSB ? 0 : 1;
for (int i = start; i < threeByteArray.length; i++)
    threeByteArray[i - start] = result[i];

希望这可以帮助 ：）

于 2013-10-07T10:14:25.027 回答
0 
Caused by: java.lang.NumberFormatException: Invalid int: ""
THERE (HexFunctions.java:73)

您正在尝试将空字符串解析为 int。请首先检查您的字符串是否具有值

if(text.length > 0){
  //parseInt
}

或者尝试在正确的位置捕获 NumberFormatException。

于 2013-10-07T10:07:53.570 回答