# Java 程序：將八進制數轉換為十進制，反之亦然 > 原文： [https://www.programiz.com/java-programming/examples/octal-decimal-convert](https://www.programiz.com/java-programming/examples/octal-decimal-convert) #### 在此程序中，您將學習如何使用 Java 中的函數將八進制數轉換為十進制數，反之亦然。 ## 示例 1：將十進制轉換為八進制的程序 ```java public class DecimalOctal { public static void main(String[] args) { int decimal = 78; int octal = convertDecimalToOctal(decimal); System.out.printf("%d in decimal = %d in octal", decimal, octal); } public static int convertDecimalToOctal(int decimal) { int octalNumber = 0, i = 1; while (decimal != 0) { octalNumber += (decimal % 8) * i; decimal /= 8; i *= 10; } return octalNumber; } } ``` 運行該程序時，輸出為： ```java 78 in decimal = 116 in octal ``` 此轉換發生為： ```java 8 | 78 8 | 9 -- 6 8 | 1 -- 1 8 | 0 -- 1 (116) ``` * * * ## 示例 2：將八進制轉換為十進制的程序 ```java public class OctalDecimal { public static void main(String[] args) { int octal = 116; int decimal = convertOctalToDecimal(octal); System.out.printf("%d in octal = %d in decimal", octal, decimal); } public static int convertOctalToDecimal(int octal) { int decimalNumber = 0, i = 0; while(octal != 0) { decimalNumber += (octal % 10) * Math.pow(8, i); ++i; octal/=10; } return decimalNumber; } } ``` 運行該程序時，輸出為： ```java 116 in octal = 78 in decimal ``` This conversion takes place as: ```java 1 * 82 + 1 * 81 + 6 * 80 = 78 ```