public class SingletonTest {
　private final int foo;
　
　private static SingletonTest instance = null;

　private SingletonTest(int foo) {
　　this.foo = foo; //←これ
　}

　public static SingletonTest getInstance(int foo) {
　　return (instance == null) ? instance = new SingletonTest(foo) : instance;
　}

　public static SingletonTest getInstance() {
　　return (instance == null) ? newInstance(1) : instance;
　}
}