Java 字符串左边填充空格

最简单的方法是使用 StringUtils.leftPad() 方法。

Maven 依赖

<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-lang3</artifactId>
    <version>3.8</version>
</dependency>

方法语法（重载）

/**
 * @param str  		- the String to pad out, may be null
 * @param size 		- the size to pad to for example:Total length of result string
 * @param padChar  	- the character or string to pad with
 * 
 * @return left padded String or oroirnal String if no padding is necessary or if null String input
 */
public static String leftPad(final String str, final int size) {...}
public static String leftPad(final String str, final int size, String padStr) {...}
public static String leftPad(final String str, final int size, final char padChar) { ... }

leftPad 方法示例

System.out.println( StringUtils.leftPad("onitroad", 8, " ") );
System.out.println( StringUtils.leftPad("onitroad", 25, " ") );
System.out.println( StringUtils.leftPad("onitroad", 10, " ") );

程序输出：

onitroad
                 onitroad
  onitroad

Java 用零左填充字符串

Java 字符串左边填充0示例

System.out.println( StringUtils.leftPad("0123456789", 10, "0") );
System.out.println( StringUtils.leftPad("789", 10, "0") );
System.out.println( StringUtils.leftPad("56789", 10, "0") );

程序输出：

0123456789
0000000789
0000056789