Java - 从字节数组中修剪尾随空格

Java - Trimming trailing whitespace from a byte array

提问by Dominic Bou-Samra

I have byte arrays similar to this:

我有与此类似的字节数组：

[77, 83, 65, 80, 79, 67, 32, 32, 32, 32, 32, 32, 32]

roughly equal to

大致等于

[M , S, A, P, O, C,  ,  ,  ,  ,  ,  ,  ] when printed as chars.

Now I want to trim the trailing whitespace so it looks like:

现在我想修剪尾随空格，使其看起来像：

[77, 83, 65, 80, 79, 67]

Easiest way to do this?

最简单的方法来做到这一点？

Edit: I don't want to deal with Strings because there is the possibility for non-printable bytes, and I can not afford to lose that data. It needs to be byte arrays :( Whenever I do convert to Strings, bytes like 01 (SOH) 02 (STX) etc are lost.

编辑：我不想处理字符串，因为有可能出现不可打印的字节，而且我不能丢失这些数据。它需要是字节数组 :( 每当我转换为字符串时， 01 (SOH) 02 (STX) 等字节都会丢失。

Edit 2: Just to clarify. DO I lose data if I convert byte arrays to Strings? Now a little confused. What about if the bytes are of a different character set?

编辑2：只是为了澄清。如果我将字节数组转换为字符串，我会丢失数据吗？现在有点糊涂了。如果字节是不同的字符集呢？

回答by Matt Ball

Without converting to a string:

不转换为字符串：

byte[] input = /* whatever */;
int i = input.length;
while (i-- > 0 && input[i] == 32) {}

byte[] output = new byte[i+1];
System.arraycopy(input, 0, output, 0, i+1);

---

---

Tests:

测试：

• [77, 83, 65, 80, 79, 67, 32, 32, 32, 32, 32, 32, 32]→ [77, 83, 65, 80, 79, 67]
• [77, 83, 65, 80, 79, 67]→ [77, 83, 65, 80, 79, 67]
• [32, 32, 32, 32, 32, 32, 32]→ []
• []→ []
• [77, 83, 65, 80, 79, 67, 32, 32, 32, 32, 32, 32, 32, 80]
  → [77, 83, 65, 80, 79, 67, 32, 32, 32, 32, 32, 32, 32, 80]

• [77, 83, 65, 80, 79, 67, 32, 32, 32, 32, 32, 32, 32]→ [77, 83, 65, 80, 79, 67]
• [77, 83, 65, 80, 79, 67]→ [77, 83, 65, 80, 79, 67]
• [32, 32, 32, 32, 32, 32, 32]→ []
• []→ []
• [77, 83, 65, 80, 79, 67, 32, 32, 32, 32, 32, 32, 32, 80]
  → [77, 83, 65, 80, 79, 67, 32, 32, 32, 32, 32, 32, 32, 80]

回答by lukastymo

• change bytes to string
• call text = text.replaceAll("\\s+$", ""); // remove only the trailing white space
• change string to bytes

• 将字节更改为字符串
• 称呼 text = text.replaceAll("\\s+$", ""); // remove only the trailing white space
• 将字符串更改为字节

回答by Vladislav Kysliy

Modification String trim()for byte[]. It cuts not only a tail of array but head too.

修改字符串trim()的byte[]。它不仅切割数组的尾部，还切割头部。

public byte[] trimArray(byte[] source) {
    int len = source.length;
    int st = 0;
    byte[] val = source;

    while ((st < len) && (val[st] <= SPACE)) {
        st++;
    }
    while ((st < len) && (val[len - 1] <= SPACE)) {
        len--;
    }
    byte[] result;
    if ((st > 0) || (len < source.length)) {
        result = new byte[len - st];
        System.arraycopy(source, st, result, 0, result.length);
    } else {
        result = source;
    }

    return result;
}

回答by digitaljoel

Easiest way? No guarantees on efficiency or performance, but it seems pretty easy.

最简单的方法？不保证效率或性能，但这似乎很容易。

byte[] results = new String(yourBytes).trim().getBytes();

回答by lynks

String s = new String(arrayWithWhitespace);
s = s.trim();
byte[] arrayWithoutWhitespace = s.getBytes();