package com.androidtv.pos/*** @author wuqiqi* date on 2020/8/19* describe 测试*/
class Apple {private var speak: String = "小啊小苹果"/* 主构造方法*/constructor(){println("主构造方法constructor()调用")}/* 次构造方法*/constructor(name:String, age:Int):this(){println("次带参数构造方法constructor(name:$name, age:$age)")}init {println("Apple init")}init {println("Apple init：name:${speak}")}/*伴生对象*/companion object {val instance: Apple by lazy {Apple("wqq", 100)}/*伴生对象中的初始化代码*/init {println("companion init 1")}init {println("companion init 2")}}
}
调用App() ，出现结果：
exclude patterns:
companion init 1
companion init 2
Apple init
Apple init：name:小啊小苹果
主构造方法constructor()调用
调用有参构造方法，出现结果
exclude patterns:
companion init 1
companion init 2
Apple init
Apple init：name:小啊小苹果
主构造方法constructor()调用
次带参数构造方法constructor(name:heihei, age:28)
可以看看 kotlin转java的代码：
package com.androidtv.pos;import kotlin.Lazy;
import kotlin.LazyKt;
import kotlin.Metadata;
import kotlin.jvm.functions.Function0;
import kotlin.jvm.internal.DefaultConstructorMarker;
import kotlin.jvm.internal.Intrinsics;
import org.jetbrains.annotations.NotNull;@Metadata(mv = {1, 1, 18},bv = {1, 0, 3},k = 1,d1 = {"\u0000\u001a\n\u0002\u0018\u0002\n\u0002\u0010\u0000\n\u0002\b\u0002\n\u0002\u0010\u000e\n\u0000\n\u0002\u0010\b\n\u0002\b\u0004\u0018\u0000 \t2\u00020\u0001:\u0001\tB\u0007\b\u0016?\u0006\u0002\u0010\u0002B\u0017\b\u0016\u0012\u0006\u0010\u0003\u001a\u00020\u0004\u0012\u0006\u0010\u0005\u001a\u00020\u0006?\u0006\u0002\u0010\u0007R\u000e\u0010\b\u001a\u00020\u0004X\u0082\u000e?\u0006\u0002\n\u0000¨\u0006\n"},d2 = {"Lcom/androidtv/pos/Apple;", "", "()V", "name", "", "age", "", "(Ljava/lang/String;I)V", "speak", "Companion", "app"}
)
public final class Apple {private String speak;@NotNullprivate static final Lazy instance$delegate;public static final Apple.Companion Companion = new Apple.Companion((DefaultConstructorMarker)null);public Apple() {this.speak = "小啊小苹果";String var1 = "Apple init";boolean var2 = false;System.out.println(var1);var1 = "Apple init：name:" + this.speak;var2 = false;System.out.println(var1);var1 = "主构造方法constructor()调用";var2 = false;System.out.println(var1);}public Apple(@NotNull String name, int age) {Intrinsics.checkParameterIsNotNull(name, "name");this();String var3 = "次带参数构造方法constructor(name:" + name + ", age:" + age + ')';boolean var4 = false;System.out.println(var3);}static {instance$delegate = LazyKt.lazy((Function0)null.INSTANCE);String var0 = "companion init 1";boolean var1 = false;System.out.println(var0);var0 = "companion init 2";var1 = false;System.out.println(var0);}@Metadata(mv = {1, 1, 18},bv = {1, 0, 3},k = 1,d1 = {"\u0000\u0014\n\u0002\u0018\u0002\n\u0002\u0010\u0000\n\u0002\b\u0002\n\u0002\u0018\u0002\n\u0002\b\u0005\b\u0086\u0003\u0018\u00002\u00020\u0001B\u0007\b\u0002?\u0006\u0002\u0010\u0002R\u001b\u0010\u0003\u001a\u00020\u00048FX\u0086\u0084\u0002?\u0006\f\n\u0004\b\u0007\u0010\b\u001a\u0004\b\u0005\u0010\u0006¨\u0006\t"},d2 = {"Lcom/androidtv/pos/Apple$Companion;", "", "()V", "instance", "Lcom/androidtv/pos/Apple;", "getInstance", "()Lcom/androidtv/pos/Apple;", "instance$delegate", "Lkotlin/Lazy;", "app"})public static final class Companion {@NotNullpublic final Apple getInstance() {Lazy var1 = Apple.instance$delegate;Apple.Companion var2 = Apple.Companion;Object var3 = null;boolean var4 = false;return (Apple)var1.getValue();}private Companion() {}// $FF: synthetic methodpublic Companion(DefaultConstructorMarker $constructor_marker) {this();}}
}
总结：由于伴生对象中的代码是在类加载时就会执行，所以伴生类初始化会先执行，再执行本身构造方法， 会把init代码 合并到构造方法中，但会插到构造方法最前面。