The code examples

How to convert an int to a formatted string in java

October 7, 2017October 12, 2017 - by Tirex - Leave a Comment

Using java.util.formatter

StringBuilder sb = new StringBuilder();
// Send all output to the Appendable object sb
Formatter formatter = new Formatter(sb, Locale.US);

// Explicit argument indices may be used to re-order output.
formatter.format("%4$2s %3$2s %2$2s %1$2s", "a", "b", "c", "d")
// -> " d  c  b  a"

// Optional locale as the first argument can be used to get
// locale-specific formatting of numbers.  The precision and width can be
// given to round and align the value.
formatter.format(Locale.FRANCE, "e = %+10.4f", Math.E);
// -> "e =    +2,7183"

// The '(' numeric flag may be used to format negative numbers with
// parentheses rather than a minus sign.  Group separators are
// automatically inserted.
formatter.format("Amount gained or lost since last statement: $ %(,.2f",
            balanceDelta);
// -> "Amount gained or lost since last statement: $ (6,217.58)"

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StringBuilder sb = new StringBuilder();

// Send all output to the Appendable object sb

Formatter formatter = new Formatter(sb, Locale.US);

// Explicit argument indices may be used to re-order output.

formatter.format("%4$2s %3$2s %2$2s %1$2s", "a", "b", "c", "d")

// -> " d c b a"

// Optional locale as the first argument can be used to get

// locale-specific formatting of numbers. The precision and width can be

// given to round and align the value.

formatter.format(Locale.FRANCE, "e = %+10.4f", Math.E);

// -> "e = +2,7183"

// The '(' numeric flag may be used to format negative numbers with

// parentheses rather than a minus sign. Group separators are

// automatically inserted.

formatter.format("Amount gained or lost since last statement: $ %(,.2f",

balanceDelta);

// -> "Amount gained or lost since last statement: $ (6,217.58)"

See the Formatter docs for other modifiers.

java

How to convert int to Integer

October 7, 2017September 1, 2018 - by Tirex - Leave a Comment

How to convert int to Integer in java. This is the most popular question asked on the forums. Here are 3 examples of how to do this.

java

How to check If a String is an Integer in Java

October 7, 2017September 1, 2018 - by Tirex - Leave a Comment

Suppose we have the following problem. User input some value, how to check that this value is a String is an integer: 1. Check by Exception

public static void main(String[] args) {
    System.out.println("Is int? " + IsIntCheckByException("12"));
}

private static boolean IsIntCheckByException(String str) {
    try {
        Integer.parseInt(str);
        return true;
    } catch (NumberFormatException nfe) {
        return false;
    }
}

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public static void main(String[] args) {

System.out.println("Is int? " + IsIntCheckByException("12"));

}

private static boolean IsIntCheckByException(String str) {

try {

Integer.parseInt(str);

return true;

} catch (NumberFormatException nfe) {

return false;

}

java

Convert String array to string in java

September 1, 2017September 3, 2018 - by Tirex - Leave a Comment

In this article, we’ll look at the String array convert to String. This can be useful for example to log query parameters.

java

Using jxls for working with Excel files in java

August 30, 2017February 10, 2018 - by Tirex - Leave a Comment

Jxls is a small Java library to make generation of Excel reports easy. Jxls uses a special markup in Excel templates to define output formatting and data layout.

java

Output data to excel file by template with jxls

August 30, 2017November 4, 2019 - by Tirex - 4 Comments.

Let’s assume we have a Java collection of Car objects that we want to output into Excel. The Car class may look like this

public class Car {
  private String brand;
  private BigDecimal price;
  // ... constructors
  // ... getters/setters
}

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public class Car {

private String brand;

private BigDecimal price;

// ... constructors

// ... getters/setters

}

To use Jxls to output …

java

How to convert integer to string in Java?

August 30, 2017October 7, 2017 - by Tirex - Leave a Comment

Let’s say you have a number x of integer type how we can convert it to a String?

java

How to repeat string n times in java?

August 27, 2017January 2, 2021 - by Tirex - Leave a Comment

Suppose you have the string ‘qwe’ and you need to repeat string ‘n’ times. Here’s how to do it: Using java 8 stream api

String newString = Collections.nCopies(3, "qwe").stream().collect(Collectors.joining("")); 

String newString = Stream.generate(() -> "qwe").limit(3).collect(Collectors.joining());

String newString = String.join("", Collections.nCopies(n, s));

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String newString = Collections.nCopies(3, "qwe").stream().collect(Collectors.joining(""));

String newString = Stream.generate(() -> "qwe").limit(3).collect(Collectors.joining());

String newString = String.join("", Collections.nCopies(n, s));

Using String.format

String s = "qwe";
int n = 3;
//this line print 'qweqweqwe'
String newString = String.format("%0" + n + "d", 0).replace("0", s);

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String s = "qwe";

int n = 3;

//this line print 'qweqweqwe'

String newString = String.format("%0" + n + "d", 0).replace("0", s);

Let us examine …

java

How to convert ‘ArrayList to String array in Java

August 26, 2017November 27, 2017 - by Tirex - Leave a Comment

Using Collection.toArray method First way to convert arraylist is to use built-in for every java collection method toArray(T[] ts) For example:

List<String> animals = new ArrayList<String>();
//add some elements
animals.add("cat");
animals.add("dog");
String[] stringArray = animals.toArray(new String[0]);
System.out.println(Arrays.toString(stringArray));

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List<String> animals = new ArrayList<String>();

//add some elements

animals.add("cat");

animals.add("dog");

String[] stringArray = animals.toArray(new String[0]);

System.out.println(Arrays.toString(stringArray));

The toArray() method without any argument returns Object[]. So you have …

java

How to compare strings in Java?

August 26, 2017February 10, 2018 - by Tirex - Leave a Comment

Test strings equality == tests object references, .equals() tests the string values. Sometimes it looks as if == compares values, because Java does some behind-the-scenes stuff to make sure identical …