如何使用String.format将字符串居中?
public class Divers { public static void main(String args[]){
String format = "|%1$-10s|%2$-10s|%3$-20s|\n";
System.out.format(format, "FirstName", "Init.", "LastName");
System.out.format(format, "Real", "", "Gagnon");
System.out.format(format, "John", "D", "Doe");
String ex[] = { "John", "F.", "Kennedy" };
System.out.format(String.format(format, (Object[])ex));
}
}
输出:
|FirstName |Init. |LastName ||Real | |Gagnon |
|John |D |Doe |
|John |F. |Kennedy |
我希望输出居中。如果我不使用’-‘标志,则输出将向右对齐。
我在API中找不到将文本居中的标志。
该文章有关于格式的一些信息,但没有对中心自圆其说。
回答:
我很快就搞定了。您现在可以StringUtils.center(String s, int size)
在中使用String.format
。
import static org.hamcrest.CoreMatchers.*;import static org.junit.Assert.assertThat;
import org.junit.Test;
public class TestCenter {
@Test
public void centersString() {
assertThat(StringUtils.center(null, 0), equalTo(null));
assertThat(StringUtils.center("foo", 3), is("foo"));
assertThat(StringUtils.center("foo", -1), is("foo"));
assertThat(StringUtils.center("moon", 10), is(" moon "));
assertThat(StringUtils.center("phone", 14, '*'), is("****phone*****"));
assertThat(StringUtils.center("India", 6, '-'), is("India-"));
assertThat(StringUtils.center("Eclipse IDE", 21, '*'), is("*****Eclipse IDE*****"));
}
@Test
public void worksWithFormat() {
String format = "|%1$-10s|%2$-10s|%3$-20s|\n";
assertThat(String.format(format, StringUtils.center("FirstName", 10), StringUtils.center("Init.", 10), StringUtils.center("LastName", 20)),
is("|FirstName | Init. | LastName |\n"));
}
}
class StringUtils {
public static String center(String s, int size) {
return center(s, size, ' ');
}
public static String center(String s, int size, char pad) {
if (s == null || size <= s.length())
return s;
StringBuilder sb = new StringBuilder(size);
for (int i = 0; i < (size - s.length()) / 2; i++) {
sb.append(pad);
}
sb.append(s);
while (sb.length() < size) {
sb.append(pad);
}
return sb.toString();
}
}
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