Multilines / Span
Java (before JDK15) does not permit strings to span lines.
/**
* Span strings on multiple lines
*
* Concatenation operator +
* String.join()
* Text Block """ (only with JDK15)
*/
package com.minte9.basics.strings;
public class Multilines {
public static void main(String[] args) {
String a = ""
+ "AAA "
+ "BBB"
;
String b = String.join("\n",
"CCC",
"DDD"
);
System.out.println(a); // AAA BBB
System.out.println(b); // CCC DDD
}
}
Padding / Strings
Use String.format() to pad strings.
/**
* To pad a string use String.format()
* Pad LEFT %6s
* Pad RIGHT %-6s
*/
package com.minte9.basics.strings;
public class Padding {
public static void main(String[] args) {
String a = "0" + String.format("%6s", "123"); // LEFT
String b = String.format("%6s", "123").replace(" ", "0");
String c = String.format("%-6s", "123").replace(" ", "0");
System.out.println(a); // 000 123
System.out.println(b); // 000123
System.out.println(c); // 123000
}
}
Converting / Integers
Conveting Strings to Integers and vice versa.T
package com.minte9.basics.strings;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNotEquals;
import org.junit.Test;
public class ConvertingTest {
@Test public void toNumberTest() {
String a = "1";
String b = "2.22";
Integer c = Integer.valueOf(a); // 1
Float d = Float.valueOf(b); // 2.22
assertEquals(c, 1, 0);
assertEquals(d, 2.23, 0.1);
assertNotEquals(c, "1");
assertNotEquals(d, 2.23, 0);
}
@Test public void toStringTest() {
int i = 11;
assertEquals("11", "" + i);
assertEquals("11", "" + String.valueOf(i));
assertEquals("11", "" + Integer.toString(i));
}
}
Last update: 531 days ago
