第一種方法:

import java.util.Scanner;

public class Rab{
	public static void main(String[]args){
		int month;
		System.out.println("請輸入養殖兔子的月份數：");
		Scanner in = new Scanner(System.in);
		month = in.nextInt();
		
		int sum[]= new int[month] ;
		sum[0] = 1;
		sum[1] = 1;
			
		for(int i=2;i<month;i++){
			sum[i] = sum[i-1]+sum[i-2];
		}
				
		System.out.println("第"+month+"個月的兔子總數是："+sum[month-1]);
		
	}
}

第二種方法:

import java.util.Scanner;


public class practies4 {
	public static void main(String[]args){
	//變數宣告；
		int n = 0; 
		while(n<3){
			GetKey gk = new GetKey();
			n = gk.getN();
		}
		System.out.println("請輸入月份數：");
		Scanner in = new Scanner(System.in);
		n = in.nextInt();
		
		int[]a = new int[n];
		a[0]=1;
		a[1]=1;
		for(int i=2;i<n;i++){
			a[i]=a[i-1]+a[i-2];
		}
		System.out.println(n);
		System.out.println(a[n-1]);
	}
}

//實現對使用者輸入內容的控制，並獲取n
class GetKey{
	private int pos;
	private String bufNum="";
	private byte[]buff =new byte[10];
	private int n;
	private int info;
	public int getN(){
		System.out.println("請輸入你想知道第多少個月的兔子總數：");
		System.out.println("月份數必須大於2");
		while(true){
			try{
				info=System.in.read();
			}catch(Exception e){
			}
			
			if(info=='\n'||info=='\r'){
				bufNum = new String(buff,0,pos);
				try{
					n=Integer.parseInt(bufNum);
				}catch(Exception e){
						n=1;
				}
				break;
			}else{
				buff[pos++]=(byte)info;
			}
		}
		return n;
	}
}