将八进制转换为二进制的Java程序

给定一个八进制数作为输入，任务是将该数转换为其等效的二进制数。

例子：

Input: Octal Number = 513
Output: Binary equivalent value is: 101001011

Explanation : 
Binary equivalent value of 5: 101
Binary equivalent value of 1: 001

Binary equivalent value of 3: 011

八进制数系统：

八进制数系统是一种位置数字系统，其基数或基数为 8，并使用 0 到 7 之间的八个不同数字。

二进制数系统：

二进制数是用基数为 2 的二进制数字系统表示的数字，它只使用两个符号：0 和 1。

八进制到二进制转换表：

Octal	Binary
0	000
1	001
2	010
3	011
4	100
5	101
6	110
7	111

方法 1：朴素的方法

在这种方法中，八进制数的输入将被视为字符串。此外，完整的字符串将逐个字符地迭代，并且对于每个字符（即八进制数字），字符评估根据上述八进制到二进制转换表的等效二进制值。每次迭代的结果将添加到结果字符串中，所有值的组合将给出所需的二进制数。下面是这个方法的实现。

Java

// Java program to convert
// Octal number to Binary
 
class OctalToBinary {
 
    // function to convert octal number
    // to its binary equivalent value
    static String converter(String octalValue)
    {
 
        // integer variable to iterate
        // the input octal string
        int i = 0;
 
        // string to store the result
        String binaryValue = "";
 
        // iterating the complete length
        // of octal string and assigning
        // the equivalent binary value
        // for each octal digit
        while (i < octalValue.length()) {
 
            // storing character according
            // to the number of iteration
            char c = octalValue.charAt((int)i);
 
            // switch case to check all
            // possible 8 conditions
            switch (c) {
            case '0':
                binaryValue += "000";
                break;
            case '1':
                binaryValue += "001";
                break;
            case '2':
                binaryValue += "010";
                break;
            case '3':
                binaryValue += "011";
                break;
            case '4':
                binaryValue += "100";
                break;
            case '5':
                binaryValue += "101";
                break;
            case '6':
                binaryValue += "110";
                break;
            case '7':
                binaryValue += "111";
                break;
            default:
                System.out.println(
                    "\nInvalid Octal Digit "
                    + octalValue.charAt((int)i));
                break;
            }
            i++;
        }
 
        // returning the final result
        return binaryValue;
    }
 
    // Driver code
    public static void main(String args[])
    {
 
        System.out.println("Octal to Binary Conversion\n");
 
        // octal number which is to be converted
        String octalNumber = "315";
        System.out.println("Octal number: " + octalNumber);
 
        // calling the converter method and
        // storing the result in a string variable
        String result = converter(octalNumber);
 
        System.out.println("Binary equivalent value is: "
                           + result);
    }
}

输出

Octal to Binary Conversion

Octal number: 315
Binary equivalent value is: 011001101

方法二：数学方法

该方法涉及完整的数学计算以获得所需的结果。八进制数的输入将被视为整数。此外，它首先被转换为其十进制等效值，然后使用数学运算从十进制数转换为其二进制等效值。下面是这个方法的实现。

Java

// Java program to convert
// Octal number to Binary
public class OctalToBinary {
 
    // function to convert octal number
    // to its binary equivalent value
    public static int converter(int octalValue)
    {
 
        // declaring all variable
        // to store the intermediate results
        int i = 0;
        int decimalValue = 0;
        int binaryValue = 0;
 
        // converting octal number
        // into its decimal equivalent
        while (octalValue != 0) {
            decimalValue
                += (octalValue % 10) * Math.pow(8, i);
            ++i;
            octalValue /= 10;
        }
 
        i = 1;
 
        // converting generated decimal number
        // to its binary equivalent
        while (decimalValue != 0) {
            binaryValue += (decimalValue % 2) * i;
            decimalValue /= 2;
            i *= 10;
        }
 
        // returning the final result
        return binaryValue;
    }
 
    // Driver code
    public static void main(String[] args)
    {
 
        System.out.println("Octal to Binary Conversion\n");
 
        // octal number which is to be converted
        int octalNumber = 315;
        System.out.println("Octal number: " + octalNumber);
 
        // calling the converter method and
        // storing the result in a string variable
        int result = converter(octalNumber);
 
        // printing the binary equivalent value
        System.out.println("Binary equivalent value is: "
                           + result);
    }
}

输出

Octal to Binary Conversion

Octal number: 315
Binary equivalent value is: 11001101

方法 3：使用内置的Java方法

Integer.parseInt() 是Java中的一个内置函数，用于将字符串解析为由基数值（方法的第二个参数）指定的数字系统。在这种方法中，八进制数的输入将被视为字符串。八进制字符串将被解析为八进制数系统的整数值。此外，八进制数将使用另一个内置方法 Integer.toBinaryString() 转换为其等效的二进制数。结果值也将是字符串数据类型。下面是实现。

Java

// Java program to convert
// Octal number to Binary
class OctalToBinary {
 
    // function to convert octal number
    // to its binary equivalent value
    public static String converter(String octalValue)
    {
 
        // parsing the string value
        // by following octal number system
        int octal = Integer.parseInt(octalValue, 8);
 
        // converting octal number to binary
        // and storing as a string
        String binaryValue = Integer.toBinaryString(octal);
 
        // returning the resultant string
        return binaryValue;
    }
 
    // Driver code
    public static void main(String args[])
    {
 
        System.out.println("Octal to Binary Conversion\n");
 
        // octal number which is to be converted
        String octalNumber = "315";
        System.out.println("Octal number: " + octalNumber);
 
        // calling the converter method and
        // storing the result in a string variable
        String result = converter(octalNumber);
 
        // printing the binary equivalent value
        System.out.println("Binary equivalent value is: "
                           + result);
    }
}

输出

Octal to Binary Conversion

Octal number: 315
Binary equivalent value is: 11001101