How do I convert decimal to octal?

By Wayan in Core API, Lang Package 0 Comment

From the code snippet below you will learn how to convert decimal to an octal string and converting back from a string of octal number to decimal. For the first conversion we can utilize the Integer.toOctalString() method. This method takes an integer number and will return the string that represent the corresponding octal number.

To convert back from octal string to decimal number we can use the Integer.parseInt() method. Which require two parameter, a string that represent an octal number, and the radix which is 8 from octal number.

package org.kodejava.lang;

public class IntegerToOctalExample {
    public static void main(String[] args) {
        int integer = 1024;
        // Converting integer value to octal string representation.
        String octal = Integer.toOctalString(integer);
        System.out.printf("Octal value of %d is '%s'.\n", integer, octal);

        // Now we converting back from octal string to integer
        // by calling Integer.parseInt and passing 8 as the radix.
        int original = Integer.parseInt(octal, 8);
        System.out.printf("Integer value of octal '%s' is %d.%n", octal, original);

        // When for formatting purposes we can actually use printf
        // or String.format to display an integer value in other
        // format (o = octal, h = hexadecimal).
        System.out.printf("Octal value of %1$d is '%1$o'.\n", integer);
    }
}

Here is the result of our program.

Octal value of 1024 is '2000'.
Integer value of octal '2000' is 1024.
Octal value of 1024 is '2000'.

How do I convert decimal to binary?

By Wayan in Core API, Lang Package 2 Comments

In this example you will learn how to convert decimal number to binary number. To convert decimal number to binary we can use Integer.toBinaryString() method. This method takes a single parameter of integer and return a string that represent the equal binary number.

If you want to convert the other way around, from binary string to decimal, you can use the Integer.parseInt() method. This method takes two parameters. First, the string that represents a binary number to be parsed. The second parameter is the radix to be used while parsing, in case for binary number the radix is 2.

package org.kodejava.lang;

public class IntegerToBinaryExample {
    public static void main(String[] args) {
        int integer = 127;
        String binary = Integer.toBinaryString(integer);
        System.out.println("Binary value of " + integer + " is "
                + binary + ".");

        int original = Integer.parseInt(binary, 2);
        System.out.println("Integer value of binary '" + binary
                + "' is " + original + ".");
    }

}

Here is the result of our program.

Binary value of 127 is 1111111.
Integer value of binary '1111111' is 127.

How do I convert decimal to hexadecimal?

By Wayan in Core API, Lang Package 0 Comment

To convert decimal number (base 10) to hexadecimal number (base 16) we can use the Integer.toHexString() method. This method takes an integer as parameter and return a string that represent the number in hexadecimal.

To convert back the number from hexadecimal to decimal number we can use the Integer.parseInt() method. This method takes two argument, the number to be converted, which is the string that represent a hexadecimal number. The second argument is the radix, we pass 16 which tell the method if the string is a hexadecimal number.

package org.kodejava.lang;

public class ToHexadecimalExample {
    public static void main(String[] args) {
        // Converting a decimal value to its hexadecimal representation 
        // can be done using Integer.toHexString() method.
        System.out.println(Integer.toHexString(1976));

        // On the other hand to convert hexadecimal string to decimal
        // we can use Integer.parseInt(string, radix) method, 
        // where radix for hexadecimal is 16.
        System.out.println(Integer.parseInt("7b8", 16));
    }
}

How do I convert primitive boolean type into Boolean object?

By Wayan in Core API, Lang Package 0 Comment

The following code snippet demonstrate how to use the Boolean.valueOf() method to convert primitive boolean value or a string into Boolean object. This method will return the corresponding Boolean object of the given primitive boolean value.

When a string value is passed to this method it will return Boolean.TRUE when the string is not null, and the value is equal, ignoring case, to the string "true". Otherwise, it will return Boolean.FALSE object.

package org.kodejava.lang;

public class BooleanValueOfExample {
    public static void main(String[] args) {
        boolean b = true;
        Boolean bool = Boolean.valueOf(b);
        System.out.println("bool = " + bool);

        // Here we test the conversion, which is likely unnecessary. But
        // here is shown the boolean true is equals to Boolean.TRUE static
        // variable and of course you can guest the boolean false value is
        // equals to Boolean.FALSE
        if (bool.equals(Boolean.TRUE)) {
            System.out.println("bool = " + bool);
        }

        // On the line below we convert a string to Boolean, it returns
        // true if and only if the string is equals to "true" otherwise it
        // returns false
        String s = "false";
        Boolean bools = Boolean.valueOf(s);
        System.out.println("bools = " + bools);

        String f = "abc";
        Boolean abc = Boolean.valueOf(f);
        System.out.println("abc = " + abc);
    }
}

The code snippet will print the following output:

bool = true
bool = true
boolS = false
abc = false

Can I create a boolean variable from string?

By Wayan in Core API, Lang Package 0 Comment

To convert a string into boolean we can use the Boolean.parseBoolean(String) method. If we pass a non null value that equals to true, ignoring case, this method will return true value. Given other values it will return a false boolean value.

package org.kodejava.lang;

public class BooleanParseExample {
    public static void main(String[] args) {
        // Parsing string "true" will result boolean true
        boolean boolA = Boolean.parseBoolean("true");
        System.out.println("boolA = " + boolA);

        // Parsing string "TRUE" also result boolean true, as the
        // parsing method is case insensitive
        boolean boolB = Boolean.parseBoolean("TRUE");
        System.out.println("boolB = " + boolB);

        // The operation below will return false, as Yes is not
        // a valid string value for boolean expression
        boolean boolC = Boolean.parseBoolean("Yes");
        System.out.println("boolC = " + boolC);

        // Parsing a number is also not a valid expression so the
        // parsing method return false
        boolean boolD = Boolean.parseBoolean("1");
        System.out.println("boolD = " + boolD);
    }
}

The code snippet above will print the following output:

boolA = true
boolB = true
boolC = false
boolD = false