Java - 对象引用的初始化方式

/**
* 四种初始化方式
* <p/>
* Created by wang on 15/8/5.
*/
class Soap {
public Soap() {
System.out.println("Soap");
}

@Override
public String toString() {
return "Constructed";
}
}

public class TestInit {
private String s1 = "Happy"; // 定义初始化
private Soap s2;
private String s3, s4;

// 实例初始化
{
s2 = new Soap();
}

public TestInit() {
s3 = "Good"; // 构造器初始化
}

@Override
public String toString() {
s4 = "Girl"; // 惰性初始化
return "TestInit{" + "s1='" + s1 + ", s2=" + s2 +
", s3='" + s3 + ", s4='" + s4 + '}';
}

public static void main(String[] args) {
TestInit ti = new TestInit();
System.out.println(ti);
}
}
/*
Output:
Soap
TestInit{s1='Happy, s2=Constructed, s3='Good, s4='Girl}
*/