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                        /后端開發
                        
                            /Java
                        
                        /Java入門第二季 升級版

上個作業求指教

package?com.trainsports;

public?class?trains?{
	public?int?people?=?0;
	public?trains(){
		System.out.print("運輸方式選擇：");
	}
	/*public?int?getPeople()?{
		return?people;
	}
	public?void?setPeople(int?people)?{
		this.people?=?people;
	}*/
	public?void?way(){
		System.out.println("各種運輸方式！");
	}

}
package?com.trainsports;

public?class?airplane?extends?trains?{
	//trains?air?=?new?airplane();
	String?way2?=?"飛機";
	public?airplane(){
		System.out.println(way2);
		System.out.println("飛機運輸方式！");
		
		people?=?200;
		System.out.println("運輸人數："+people);
	}
	public?void?way(){
		System.out.println("在天上飛行運輸！");
	}

}
package?com.trainsports;

public?class?bike?extends?trains?{
	//trains?b?=?new?bike();
	
	public?bike(){
		System.out.println("自行車趕路方式！");
		
		people?=?2;
		System.out.println("運輸人數："+people);
	}
	public?void?way(){
		System.out.println("人力蹬車運輸方式！");
	}
	

}
package?com.trainsports;

public?class?boat?extends?trains?{
	//trains?bo?=?new?boat();
	public?boat(){
		System.out.println("輪船運輸方式！");
		
		people=500;
		System.out.println("運輸人數："+people);
	}
	public?void?way(){
		System.out.println("水中運輸方方式！");
	}

}
package?com.trainsports;

public?class?bus?extends?trains?{
	//trains?b=?new?bus();
	public?bus(){
		System.out.println("公交運輸方式");
		
		people?=?40;
		System.out.println("運輸人數："+people);
	}
	public?void?way(){
		System.out.println("公路運輸方式！");
	}

}
package?com.trainsports;
import?java.util.Scanner;
public?class?Initial?{

	public?static?void?main(String[]?args)?{
		//?TODO?Auto-generated?method?stub
		
		Scanner?input?=?new?Scanner(System.in);
		Initial?in?=?new?Initial();
		while(true){
			System.out.println("請選擇你要查詢的交通工具：");
			System.out.println("1、自行車??2、公交車??3、輪船??4、飛機?5、退出");
			
			int?temp?=?input.nextInt();
			if(temp?==?5)
			{
				System.out.print("退出程序");
		????break;
			}
			else{
				?in.chiose(temp);
			????
			}
			?
		}
		input.close();
	}
	
	public?void?chiose(int?temp){
		switch(temp){
		case?1:
			trains?bike?=?new?bike();
			bike.way();
			break;
		case?2:
			trains?bus??=?new?bus();
			bus.way();
			break;
		case?3:
			trains?boat?=?new?boat();
			boat.way();
			break;
		case?4:
			trains?airplane?=?new?airplane();
			airplane.way();
			break;
			default:
				System.out.println("輸入出錯，請重新輸入：");
				break;
				
		}
	}

}
大概就這么多了?字類不能繼承父類的私有成員變量?但是我要改變他?使用setter時?建立一個父類的對象就會進入死循環啊?怎么做啊