下面是一个基于String的解决方案。适用于字符串的格式，适用于可变长度。

public static String PadLeft(String stringToPad, int padToLength){
    String retValue = null;
    if(stringToPad.length() < padToLength) {
        retValue = String.format("%0" + String.valueOf(padToLength - stringToPad.length()) + "d%s",0,stringToPad);
    }
    else{
        retValue = stringToPad;
    }
    return retValue;
}

public static void main(String[] args) {
    System.out.println("'" + PadLeft("test", 10) + "'");
    System.out.println("'" + PadLeft("test", 3) + "'");
    System.out.println("'" + PadLeft("test", 4) + "'");
    System.out.println("'" + PadLeft("test", 5) + "'");
}

输出: “000000测试” “测试” “测试” “0测试”

你可以使用apache commons StringUtils

StringUtils.leftPad("129018", 10, "0");

https://commons.apache.org/proper/commons lang/javadocs/api - 2.6 - / - org/apache/commons/lang/stringutils.html # leftPad (% 20 int,以% 20字符)

String str = "129018";
StringBuilder sb = new StringBuilder();

for (int toPrepend=10-str.length(); toPrepend>0; toPrepend--) {
    sb.append('0');
}

sb.append(str);
String result = sb.toString();

    int number = -1;
    int holdingDigits = 7;
    System.out.println(String.format("%0"+ holdingDigits +"d", number));

刚刚在采访中问过这个问题........

我的答案如下，但这个(上面提到的)要好得多——>

管柱。format(“% 05d”,全国矿工工会);

我的回答是:

static String leadingZeros(int num, int digitSize) {
    //test for capacity being too small.

    if (digitSize < String.valueOf(num).length()) {
        return "Error : you number  " + num + " is higher than the decimal system specified capacity of " + digitSize + " zeros.";

        //test for capacity will exactly hold the number.
    } else if (digitSize == String.valueOf(num).length()) {
        return String.valueOf(num);

        //else do something here to calculate if the digitSize will over flow the StringBuilder buffer java.lang.OutOfMemoryError 

        //else calculate and return string
    } else {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < digitSize; i++) {
            sb.append("0");
        }
        sb.append(String.valueOf(num));
        return sb.substring(sb.length() - digitSize, sb.length());
    }
}

Satish的解决方案在预期的答案中是非常好的。我想通过添加变量n到格式化字符串而不是10个字符来使它更通用。

int maxDigits = 10;
String str = "129018";
String formatString = "%"+n+"s";
String str2 = String.format(formatString, str).replace(' ', '0');
System.out.println(str2);

这在大多数情况下都有效

我用过这个:

DecimalFormat numFormat = new DecimalFormat("00000");
System.out.println("Code format: "+numFormat.format(123));

结果:00123

我希望它对你有用!