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java的static關(guān)鍵字

Java

古_(tái)_月 2016-01-08 21:51:18

今天遇到一個(gè)很糾結(jié)的問題,有人問:有什么方法可以直接通過static關(guān)鍵字的使用來實(shí)現(xiàn)對(duì)某個(gè)對(duì)象只能new 3次,第四次new的時(shí)候得到的對(duì)象就是null?各位大神:請(qǐng)問你們有辦法嗎?我的思路使用的單例模式結(jié)合stati關(guān)鍵字來想的,但是問題是這樣的話在實(shí)例化的時(shí)候就不是使用new關(guān)鍵字來實(shí)現(xiàn),而是使用了方法,public class Card { private String password; private String username; public static int count = 1; private static Card card = null; private Card(String username) { } // 寫一個(gè)創(chuàng)建Card對(duì)象的方法 public static Card getCard(String username) { if (count <= 3) { card = new Card(username); count++; return card; } else { System.out.println("第四次執(zhí)行了"); return null; } }坐等各位大神解答!謝謝

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Its_forever

TA貢獻(xiàn)361條經(jīng)驗(yàn) 獲得超328個(gè)贊

public?class?Card?{
	String?name;
	static?Card?card;???????????????//靜態(tài)對(duì)象card
	public?static?Card?getCard()?{??//靜態(tài)方法getCard
		card?=?new?Card();
		return?card;
	}
	public?static?void?main(String[]?args)?{
		int?count?=?1;
		do?{
				System.out.println("第"+count+"次調(diào)用");
				getCard();???????//調(diào)用3次getCard，new?三次card對(duì)象。
				System.out.println("第"+count+"次調(diào)用結(jié)束");				
				count++;
		}while(count?<=?3);
		System.out.println("第四次調(diào)用");
			card?=?null;
			System.out.println(card);
	}
}

不知道這樣算不算符合題意。

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古_(tái)_月
謝謝你

回復(fù) 2016-01-09

產(chǎn)品經(jīng)理不是經(jīng)理

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public?class?Card{
????public?static?int?sum=0;
????private?Card(){}
????public?static?Card?getCard(){
	if(Card.sum>2)?{
	????System.out.println("對(duì)象實(shí)例超過3!");
	????return?null;
	}else?{
	????Card.sum++;
	????return?new?Card();
	}
}

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