Java - 对象引用的初始化方式

Java对象引用的初始化方式:
(1) 在定义对象的位置;
(2) 在类的构造器中;
(3) 在使用对象之前, 即惰性初始化;
(4) 实例初始化.

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代码

/** * 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} */

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