companion object和object 从kotlin转java分析

说明

companion object 中
companion类中的方法是普通的方法
在外部类中生成静态变量，静态companion 对象

object MyClass2 中
类中方法是普通方法
在MyClass2中生成静态变量，静态MyClass2对象，

一 companion object 使用 kotlin转java

package test.eclass Test1 {}fun main() {
//    MyClass.MyClass2.printHello()MyClass.printHello()}
class MyClass {var a  =10companion  object  {var b =1
//        @JvmStaticfun printHello() {println("Hello, World!")}}
}调用方法
//MyClass.printHello()------------------------------------------
// Test1.java
package test.e;import kotlin.Metadata;@Metadata(mv = {2, 0, 0},k = 1,xi = 48,d1 = {"\u0000\f\n\u0002\u0018\u0002\n\u0002\u0010\u0000\n\u0002\b\u0002\u0018\u00002\u00020\u0001B\u0005¢\u0006\u0002\u0010\u0002¨\u0006\u0003"},d2 = {"Ltest/e/Test1;", "", "()V", "untitled"}
)
public final class Test1 {
}
// MyClass.java
package test.e;import kotlin.Metadata;
import kotlin.jvm.internal.DefaultConstructorMarker;
import org.jetbrains.annotations.NotNull;@Metadata(mv = {2, 0, 0},k = 1,xi = 48,d1 = {"\u0000\u0014\n\u0002\u0018\u0002\n\u0002\u0010\u0000\n\u0002\b\u0002\n\u0002\u0010\b\n\u0002\b\u0006\u0018\u0000 \t2\u00020\u0001:\u0001\tB\u0005¢\u0006\u0002\u0010\u0002R\u001a\u0010\u0003\u001a\u00020\u0004X\u0086\u000e¢\u0006\u000e\n\u0000\u001a\u0004\b\u0005\u0010\u0006\"\u0004\b\u0007\u0010\b¨\u0006\n"},d2 = {"Ltest/e/MyClass;", "", "()V", "a", "", "getA", "()I", "setA", "(I)V", "Companion", "untitled"}
)
public final class MyClass {@NotNull**public static final Companion Companion = new Companion((DefaultConstructorMarker)null);**private int a = 10;private static int b = 1;public final int getA() {return this.a;}public final void setA(int var1) {this.a = var1;}@Metadata(mv = {2, 0, 0},k = 1,xi = 48,d1 = {"\u0000\u001a\n\u0002\u0018\u0002\n\u0002\u0010\u0000\n\u0002\b\u0002\n\u0002\u0010\b\n\u0002\b\u0005\n\u0002\u0010\u0002\n\u0000\b\u0086\u0003\u0018\u00002\u00020\u0001B\u0007\b\u0002¢\u0006\u0002\u0010\u0002J\u0006\u0010\t\u001a\u00020\nR\u001a\u0010\u0003\u001a\u00020\u0004X\u0086\u000e¢\u0006\u000e\n\u0000\u001a\u0004\b\u0005\u0010\u0006\"\u0004\b\u0007\u0010\b¨\u0006\u000b"},d2 = {"Ltest/e/MyClass$Companion;", "", "()V", "b", "", "getB", "()I", "setB", "(I)V", "printHello", "", "untitled"})public static final class Companion {private Companion() {}public final int getB() {return MyClass.b;}public final void setB(int var1) {MyClass.b = var1;}public final void printHello() {String var1 = "Hello, World!";System.out.println(var1);}// $FF: synthetic methodpublic Companion(DefaultConstructorMarker $constructor_marker) {this();}}
}
// Test1Kt.java
package test.e;import kotlin.Metadata;@Metadata(mv = {2, 0, 0},k = 2,xi = 48,d1 = {"\u0000\b\n\u0000\n\u0002\u0010\u0002\n\u0000\u001a\u0006\u0010\u0000\u001a\u00020\u0001¨\u0006\u0002"},d2 = {"main", "", "untitled"}
)
public final class Test1Kt {public static final void main() {MyClass.Companion.printHello();}// $FF: synthetic methodpublic static void main(String[] args) {main();}
}

二 object kotlin转java

package test.eclass Test1 {}fun main() {MyClass.MyClass2.printHello()
//    MyClass.printHello()}
class MyClass {var a  =10object MyClass2 {var b =1
//        @JvmStaticfun printHello() {println("Hello, World!")}}
}调用方法
//MyClass.printHello()------------------------------
// Test1.java
package test.e;import kotlin.Metadata;@Metadata(mv = {2, 0, 0},k = 1,xi = 48,d1 = {"\u0000\f\n\u0002\u0018\u0002\n\u0002\u0010\u0000\n\u0002\b\u0002\u0018\u00002\u00020\u0001B\u0005¢\u0006\u0002\u0010\u0002¨\u0006\u0003"},d2 = {"Ltest/e/Test1;", "", "()V", "untitled"}
)
public final class Test1 {
}
// MyClass.java
package test.e;import kotlin.Metadata;
import org.jetbrains.annotations.NotNull;@Metadata(mv = {2, 0, 0},k = 1,xi = 48,d1 = {"\u0000\u0014\n\u0002\u0018\u0002\n\u0002\u0010\u0000\n\u0002\b\u0002\n\u0002\u0010\b\n\u0002\b\u0006\u0018\u00002\u00020\u0001:\u0001\tB\u0005¢\u0006\u0002\u0010\u0002R\u001a\u0010\u0003\u001a\u00020\u0004X\u0086\u000e¢\u0006\u000e\n\u0000\u001a\u0004\b\u0005\u0010\u0006\"\u0004\b\u0007\u0010\b¨\u0006\n"},d2 = {"Ltest/e/MyClass;", "", "()V", "a", "", "getA", "()I", "setA", "(I)V", "MyClass2", "untitled"}
)
public final class MyClass {private int a = 10;public final int getA() {return this.a;}public final void setA(int var1) {this.a = var1;}@Metadata(mv = {2, 0, 0},k = 1,xi = 48,d1 = {"\u0000\u001a\n\u0002\u0018\u0002\n\u0002\u0010\u0000\n\u0002\b\u0002\n\u0002\u0010\b\n\u0002\b\u0005\n\u0002\u0010\u0002\n\u0000\bÆ\u0002\u0018\u00002\u00020\u0001B\u0007\b\u0002¢\u0006\u0002\u0010\u0002J\u0006\u0010\t\u001a\u00020\nR\u001a\u0010\u0003\u001a\u00020\u0004X\u0086\u000e¢\u0006\u000e\n\u0000\u001a\u0004\b\u0005\u0010\u0006\"\u0004\b\u0007\u0010\b¨\u0006\u000b"},d2 = {"Ltest/e/MyClass$MyClass2;", "", "()V", "b", "", "getB", "()I", "setB", "(I)V", "printHello", "", "untitled"})public static final class MyClass2 {@NotNull**public static final MyClass2 INSTANCE = new MyClass2();**private static int b = 1;private MyClass2() {}public final int getB() {return b;}public final void setB(int var1) {b = var1;}public final void printHello() {String var1 = "Hello, World!";System.out.println(var1);}}
}
// Test1Kt.java
package test.e;import kotlin.Metadata;@Metadata(mv = {2, 0, 0},k = 2,xi = 48,d1 = {"\u0000\b\n\u0000\n\u0002\u0010\u0002\n\u0000\u001a\u0006\u0010\u0000\u001a\u00020\u0001¨\u0006\u0002"},d2 = {"main", "", "untitled"}
)
public final class Test1Kt {public static final void main() {MyClass.MyClass2.INSTANCE.printHello();}// $FF: synthetic methodpublic static void main(String[] args) {main();}
}