单例模式

package

test;

class

Singleton

{

private

static

Singleton instance;

private

Singleton(){}

public

static

Singleton getInstance()

{

if

(instance==

null

)

{

instance=

new

Singleton();

}

return

instance;

}

}

public

class

JTest

{

public

static

void

main(String[] args)

{

Singleton s1=Singleton.getInstance();

Singleton s2=Singleton.getInstance();

System.out.println(s1==s2);

}

}