如何格式化带有前导零的Java字符串？
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How to format a Java string with leading zero?
提问by Roy
Here is the String, for example:
这是字符串，例如：
"Apple"
and I would like to add zero to fill in 8 chars:
我想添加零来填充 8 个字符：
"000Apple"
How can I do so?
我怎么能这样做？
采纳答案by Chris Lercher
In case you have to do it without the help of a library:
如果您必须在没有图书馆帮助的情况下执行此操作：
("00000000" + "Apple").substring("Apple".length())
(Works, as long as your String isn't longer than 8 chars.)
（有效，只要您的字符串不超过 8 个字符。）
回答by Bozho
StringUtils.leftPad(yourString, 8, '0');
This is from commons-lang. See javadoc
这是来自commons-lang。见javadoc
回答by Alex Rashkov
public class LeadingZerosExample {
public static void main(String[] args) {
int number = 1500;
// String format below will add leading zeros (the %0 syntax)
// to the number above.
// The length of the formatted string will be 7 characters.
String formatted = String.format("%07d", number);
System.out.println("Number with leading zeros: " + formatted);
}
}
回答by kaliatech
Use Apache Commons StringUtils.leftPad(or look at the code to make your own function).
使用Apache Commons StringUtils.leftPad（或查看代码制作自己的函数）。
回答by mR_fr0g
It isn't pretty, but it works. If you have access apache commons i would suggest that use that
它不漂亮，但它有效。如果您可以访问 apache commons，我建议您使用它
if (val.length() < 8) {
for (int i = 0; i < val - 8; i++) {
val = "0" + val;
}
}
回答by Arne Deutsch
public class PaddingLeft {
public static void main(String[] args) {
String input = "Apple";
String result = "00000000" + input;
int length = result.length();
result = result.substring(length - 8, length);
System.out.println(result);
}
}
回答by bragboy
You may have to take care of edgecase. This is a generic method.
您可能需要处理边缘情况。这是一个通用的方法。
public class Test {
public static void main(String[] args){
System.out.println(padCharacter("0",8,"hello"));
}
public static String padCharacter(String c, int num, String str){
for(int i=0;i<=num-str.length()+1;i++){str = c+str;}
return str;
}
}
回答by robert_x44
String input = "Apple";
StringBuffer buf = new StringBuffer(input);
while (buf.length() < 8) {
buf.insert(0, '0');
}
String output = buf.toString();
回答by Fathah Rehman P
public static void main(String[] args)
{
String stringForTest = "Apple";
int requiredLengthAfterPadding = 8;
int inputStringLengh = stringForTest.length();
int diff = requiredLengthAfterPadding - inputStringLengh;
if (inputStringLengh < requiredLengthAfterPadding)
{
stringForTest = new String(new char[diff]).replace("String.format("%0"+length+"d",0)
", "0")+ stringForTest;
}
System.out.println(stringForTest);
}
回答by ChadyWady
You can use the String.format method as used in another answer to generate a string of 0's,
您可以使用另一个答案中使用的 String.format 方法来生成一个 0 的字符串，
public String leadingZeros(String s, int length) {
if (s.length() >= length) return s;
else return String.format("%0" + (length-s.length()) + "d%s", 0, s);
}
This can be applied to your problem by dynamically adjusting the number of leading 0's in a format string:
这可以通过动态调整格式字符串中前导 0 的数量来解决您的问题：
##代码##It's still a messy solution, but has the advantage that you can specify the total length of the resulting string using an integer argument.
它仍然是一个凌乱的解决方案，但优点是您可以使用整数参数指定结果字符串的总长度。
