Question

有一个字符串“早上好”。我想删除字符串开头的边距（可能不是空格，也许是换行符）并保留边距的中间和后面。怎么做？

Answer 1

虽然trim()删除了前导和尾随空格，但只删除前导空格，您需要实现自己的ltrim方法，如下所示：

public static String ltrim(String s) {
    int i = 0;
    while (i < s.length() && Character.isWhitespace(s.charAt(i))) {
        i++;
    }
    return s.substring(i);
}

String myString = " whitespace be gone!";
String trimmedString = ltrim( myString );

Answer 2

正则表达式在这里运作良好。当一个或多个空白字符（\\ s +）出现在短语（^）的开头时，用空字符串替换那些前导空格字符。

private static String trimLeading(String value) {
    return value != null ? value.replaceFirst("^\\s+", "") : null;
}

使用JUnit / hamcrest测试它：

@Test
public void test() {
    assertThat(trimLeading("good morning "), is("good morning "));
    assertThat(trimLeading(" good morning "), is("good morning "));
    assertThat(trimLeading("  good morning "), is("good morning "));
    assertThat(trimLeading("\ngood morning "), is("good morning "));
    assertThat(trimLeading("\rgood morning "), is("good morning "));
    assertThat(trimLeading("\tgood morning "), is("good morning "));
    assertThat(trimLeading(" \t \n \r  good morning "), is("good morning "));
}

Answer 3

String b=" This is for test "
for(int i=0;i<=b.length()-1;i++)  
    {  
     char temp=b.charAt(i);  
     if(temp==' ')  
     {  
      whitespaceNumber++;  
     }  
    }  
    System.out.println("Whitespace number is : "+whitespaceNumber);

如何删除字符串前面的空白？

3 个答案: