Kotlin-类
构造函数
Java
final File file = new File("file.txt");
Kotlin
val file = File("file.txt")
类
Java
public final class User {
}
Kotlin
class User
公开类
Java
public class User {
}
Kotlin
open class User
属性类
Java
final class User {private final String name;public User(String name) {this.name = name;}public String getName() {return name;}}
Kotlin
class User(val name: String)
有参数的构造函数
Java
final class User {private String name;public User(String name) {this.name = name;}public String getName() {return name;}public void setName(String name) {this.name = name;}}
Kotlin
class User(var name: String)
构造函数中的可选参数
Java
final class User {private String name;private String lastName;public User(String name) {this(name, "");}public User(String name, String lastName) {this.name = name;this.lastName = lastName;}// And Getters & Setters}
Kotlin
class User(var name: String, var lastName: String = "")
对类中参数赋值
Java
public class Document {private String id = "00x";public String getId() {return id;}public void setId(String id) {if(id != null && !id.isEmpty()) {this.id = id;}}}
Kotlin
class Document{var id : String = "00x"set(value) {if(value.isNotEmpty()) field = value}
}
抽象类
Java
public abstract class Document{public abstract int calculateSize();
}public class Photo extends Document{@Overridepublic int calculateSize() {}
}
Kotlin
abstract class Document {abstract fun calculateSize(): Int
}class Photo : Document() {override fun calculateSize(): Int {}
}
单例类
Java
public class Document {private static final Document INSTANCE = new Document();public static Document getInstance(){return INSTANCE;}}Kotlin
object Document {}
扩展类
Java
public class ByteArrayUtils {public static String toHexString(byte[] data) {}}final byte[] dummyData = new byte[10];final String hexValue = ByteArrayUtils.toHexString(dummyData);
Kotlin
fun ByteArray.toHex() : String {}val dummyData = byteArrayOf()
val hexValue = dummyData.toHex()
内部类
Java
public class Documment {class InnerClass {}}
Kotlin
class Document {inner class InnerClass
}
嵌套类
Java
public class Documment {public static class InnerClass {}}
Kotlin
class Document {class InnerClass}
接口
Java
public interface Printable {void print();
}public class Document implements Printable {@Overridepublic void print() {}
}
Kotlin
interface Printable{fun print()
}class Document : Printable{override fun print() {}
}