# Java 程序：十進制到八進制的轉換 > 原文： [https://beginnersbook.com/2014/07/java-program-for-decimal-to-octal-conversion/](https://beginnersbook.com/2014/07/java-program-for-decimal-to-octal-conversion/) 在本教程中，我們將學習以下兩種方法**將十進制數轉換為等效的八進制數**。 1）使用預定義的方法[`Integer.toOctalString(int num)`](https://docs.oracle.com/javase/7/docs/api/java/lang/Integer.html#toOctalString(int)) 2）編寫我們自己的轉換邏輯 ```java import java.util.Scanner; class DecimalToOctalExample { public static void main(String args[]) { Scanner input = new Scanner( System.in ); System.out.print("Enter a decimal number : "); int num =input.nextInt(); /* Method 1: * Using predefined method toOctalString(int) * Pass the decimal number to this method and * it would return the equivalent octal number */ String octalString = Integer.toOctalString(num); System.out.println("Method 1: Decimal to octal: " + octalString); /* Method 2: * Writing your own logic: Here we will write * our own logic for decimal to octal conversion */ // For storing remainder int rem; // For storing result String str=""; // Digits in Octal number system char dig[]={'0','1','2','3','4','5','6','7'}; while(num>0) { rem=num%8; str=dig[rem]+str; num=num/8; } System.out.println("Method 2: Decimal to octal: "+str); } } ``` **輸出：** ```java Enter a decimal number : 123 Method 1: Decimal to octal: 173 Method 2: Decimal to octal: 173 ```