Java字符串前用零补齐

源程序代码

private static final String FORMAT_STRING = "00000000";

/**
 * 字符串前用零补齐
 *
 * @param src 原始字符串
 * @return 补齐后的字符串
 */
public static String formatWithMakingUp(String src) {
    if (null == src) {
        return null;
    }
    int delta = FORMAT_STRING.length() - src.length();
    if (delta <= 0) {
        return src;
    }
    return FORMAT_STRING.substring(0, delta) + src;
}

测试用例

/**
 * @author Yawei Xi
 */
public class Test {

    private static final String FORMAT_STRING = "00000000";

    /**
     * 字符串前用零补齐
     *
     * @param src 原始字符串
     * @return 补齐后的字符串
     */
    public static String formatWithMakingUp(String src) {
        if (null == src) {
            return null;
        }
        int delta = FORMAT_STRING.length() - src.length();
        if (delta <= 0) {
            return src;
        }
        return FORMAT_STRING.substring(0, delta) + src;
    }

    public static void main(String[] args) {
        String a = "1";
        String b = "12";
        String c = "123";
        String d = "1234";
        String e = "12345";
        String f = "123456";
        String g = "1234567";
        String h = "12345678";
        String i = "123456789";
        System.out.println(formatWithMakingUp(a));
        System.out.println(formatWithMakingUp(b));
        System.out.println(formatWithMakingUp(c));
        System.out.println(formatWithMakingUp(d));
        System.out.println(formatWithMakingUp(e));
        System.out.println(formatWithMakingUp(f));
        System.out.println(formatWithMakingUp(g));
        System.out.println(formatWithMakingUp(h));
        System.out.println(formatWithMakingUp(i));
    }
}

输出结果

00000001
00000012
00000123
00001234
00012345
00123456
01234567
12345678
123456789