这是另一个例子。允许您选择在字符串的开头和结尾添加不同数量的填充字符时如何处理中心。
使用 Java 11 String::repeat。
public class Strings {
public enum Lean {
START,
END
}
public static String center(String value, int targetLength, Lean lean) {
return center(value, targetLength, lean, ' ');
}
private static String center(String value, int targetLength, Lean lean, char pad) {
if (targetLength < 1) {
throw new IllegalArgumentException("Cannot center something into less than one space.");
}
int sourceLength = value.length();
if (sourceLength == targetLength) {
return value;
}
int paddingToAdd = targetLength - sourceLength;
int half = paddingToAdd / 2;
String spad = Character.toString(pad);
String padding = spad.repeat(half);
String startExtra = "";
String endExtra = "";
if (paddingToAdd % 2 == 1) {
if (lean == Lean.START) {
endExtra = spad;
} else {
startExtra = spad;
}
}
return padding + startExtra + value + endExtra + padding;
}
}
public class StringsTest {
@Test
public void centerAbcIn9LeanStart() {
doTest(
"abc",
9,
Strings.Lean.START,
" abc "
);
}
@Test
public void centerAbcIn9LeanEnd() {
doTest(
"abc",
9,
Strings.Lean.END,
" abc "
);
}
@Test
public void centerAbcIn10LeanStart() {
doTest(
"abc",
10,
Strings.Lean.START,
" abc "
);
}
@Test
public void centerAbcIn10LeanEnd() {
doTest(
"abc",
10,
Strings.Lean.END,
" abc "
);
}
@Test
public void centerAbcdIn9LeanStart() {
doTest(
"abcd",
9,
Strings.Lean.START,
" abcd "
);
}
@Test
public void centerAbcdIn9LeanEnd() {
doTest(
"abcd",
9,
Strings.Lean.END,
" abcd "
);
}
@Test
public void centerAbcdIn10LeanStart() {
doTest(
"abcd",
10,
Strings.Lean.START,
" abcd "
);
}
@Test
public void centerAbcdIn10LeanEnd() {
doTest(
"abcd",
10,
Strings.Lean.START,
" abcd "
);
}
@Test
public void centerAIn1LeanStart() {
doTest(
"a",
1,
Strings.Lean.START,
"a"
);
}
@Test
public void centerAIn1LeanEnd() {
doTest(
"a",
1,
Strings.Lean.END,
"a"
);
}
@Test
public void centerAIn2LeanStart() {
doTest(
"a",
2,
Strings.Lean.START,
"a "
);
}
@Test
public void centerAIn2LeanEnd() {
doTest(
"a",
2,
Strings.Lean.END,
" a"
);
}
@Test
public void centerAIn3LeanStart() {
doTest(
"a",
3,
Strings.Lean.START,
" a "
);
}
@Test
public void centerAIn3LeanEnd() {
doTest(
"a",
3,
Strings.Lean.END,
" a "
);
}
@Test
public void centerAbIn3LeanStart() {
doTest(
"ab",
3,
Strings.Lean.START,
"ab "
);
}
@Test
public void centerAbIn3LeanEnd() {
doTest(
"ab",
3,
Strings.Lean.END,
" ab"
);
}
public void doTest(String value, int targetLength, Strings.Lean lean, String expected) {
assertThat(
"Test setup error: targetLength != expected.length()",
targetLength,
equalTo(expected.length()));
assertThat(
"Test setup error: value != expected.trim()",
value,
equalTo(expected.trim()));
String actual = Strings.center(value, targetLength, lean);
assertThat(actual, equalTo(expected));
}
}