Kotlin Class

普通 Class

kotlin

class TestClz {val name: String = "hsw"val age: Int = 18
}

java

public final class TestClz {@NotNullprivate final String name = "hsw";private final int age = 18;@NotNullpublic final String getName() {return this.name;}public final int getAge() {return this.age;}
}

转换为Java后的变化

1. 类被 final 修饰，不可继承；加上open 可以去掉 final
2. var修饰的属性添加了get set 方法 ， val 只有·get 方法

data class

kotlin

data class TestClz(val name: String, var age: Int)

java

public final class TestClz {@NotNullprivate final String name;private int age;@NotNullpublic final String getName() {return this.name;}public final int getAge() {return this.age;}public final void setAge(int var1) {this.age = var1;}public TestClz(@NotNull String name, int age) {Intrinsics.checkNotNullParameter(name, "name");super();this.name = name;this.age = age;}@NotNullpublic final String component1() {return this.name;}public final int component2() {return this.age;}@NotNullpublic final TestClz copy(@NotNull String name, int age) {Intrinsics.checkNotNullParameter(name, "name");return new TestClz(name, age);}// $FF: synthetic methodpublic static TestClz copy$default(TestClz var0, String var1, int var2, int var3, Object var4) {if ((var3 & 1) != 0) {var1 = var0.name;}if ((var3 & 2) != 0) {var2 = var0.age;}return var0.copy(var1, var2);}@NotNullpublic String toString() {return "TestClz(name=" + this.name + ", age=" + this.age + ")";}public int hashCode() {String var10000 = this.name;return (var10000 != null ? var10000.hashCode() : 0) * 31 + Integer.hashCode(this.age);}public boolean equals(@Nullable Object var1) {if (this != var1) {if (var1 instanceof TestClz) {TestClz var2 = (TestClz)var1;if (Intrinsics.areEqual(this.name, var2.name) && this.age == var2.age) {return true;}}return false;} else {return true;}}
}

转换为Java后的变化

1. 类被 final 修饰，不可继承；加上open 可以去掉 final
2. var修饰的属性添加了get set 方法 ， val 只有·get 方法
3. 实现了 toString equal hashCode 方法
4. 类似于java bean

object

object TestClz {val name: String = "hsw"var age: Int = 18fun getInfo(): String {return "${name}-${age}"}
}

public final class TestClz {@NotNullprivate static final String name;private static int age;@NotNullpublic static final TestClz INSTANCE;@NotNullpublic final String getName() {return name;}public final int getAge() {return age;}public final void setAge(int var1) {age = var1;}@NotNullpublic final String getInfo() {return name + '-' + age;}private TestClz() {}static {TestClz var0 = new TestClz();INSTANCE = var0;name = "hsw";age = 18;}
}

转换为Java后的变化

1. 类被 final 修饰，不可继承；加上open 可以去掉 final
2. var修饰的属性添加了get set 方法 ， val 只有·get 方法
3. 饿汉式实现了单例
4. java 不可直接调用get set 需要通过INSTANCE , 属性和方法 加上@JvmStatic 可以转换为静态属性/方法 直接调用

内部类

class TestClz {val name: String = "hsw"companion object {val grade = 12Lfun getInfo() {println("name-$name")}}object CCS {val grade = 12Lfun getSome() {println("name-$name")}}class Info {val grade = 12Lfun getSome() {println("name-$name")}}inner class WC {val grade = 12Lfun getSome() {println("name-${name}")}}
}

public final class TestClz {@NotNullprivate final String name = "hsw";private static final long grade = 12L;@NotNullpublic static final Companion Companion = new Companion((DefaultConstructorMarker)null);@NotNullpublic final String getName() {return this.name;}// companion 伴生对象// kotlin 可直接访问属性和方法// java 需要通过 Companion 对象访问public static final class Companion {public final long getGrade() {return TestClz.grade;}public final void getInfo() {}private Companion() {}// $FF: synthetic methodpublic Companion(DefaultConstructorMarker $constructor_marker) {this();}}// object 相当于通过单例实现静态内部类对象public static final class CCS {private static final long grade;@NotNullpublic static final CCS INSTANCE;public final long getGrade() {return grade;}public final void getSome() {}private CCS() {}static {CCS var0 = new CCS();INSTANCE = var0;grade = 12L;}}// 普通 class 相当于静态内部类，需要实例化调用方法public static final class Info {private final long grade = 12L;public final long getGrade() {return this.grade;}public final void getSome() {}}// inner class 内部类，可以直接使用外部类的属性和方法public final class WC {private final long grade = 12L;public final long getGrade() {return this.grade;}public final void getSome() {String var1 = "name-" + TestClz.this.getName();System.out.println(var1);}})
}