kotlin装箱和拆箱

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kotlin装箱和拆箱

hello熊本 2018-04-07 12:41:49 浏览595
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一、首先来看一下Java中的装箱和拆箱

package cn.kotliner.java.box;

/**
 * Created by wangdong
 * 在Java中Integer是int的包装类
 * 下面两个方法是重载的不同的两个方法
 * 而在Kotlin中int和Integer合二为一成Int了'
 * 类型的还有Double等
 */
public interface BoxIf1 {
    String get(int key);

    String get(Integer key);
}

二、用kotlin来实现一中的接口

package cn.kotliner.kotlin.box

import cn.kotliner.java.box.BoxIf1

/**
 * Created by wangdong
 * kotlin的装箱和拆箱
 */
class BoxImpl1: BoxIf1{

    //kotlin实现Java的BoxIf1接口
    //两个方法因为int和Integer合并成Int,就合二为一了
    override fun get(key: Int): String {
        return "Hello"
    }

//    override fun get(key: Int?): String {
//        return "Hello"
//    }
}

三、看一下继承了Map接口的Java接口

package cn.kotliner.java.box;

import java.util.Map;

/**
 * Created by wangdong
 * 定义一个接口,继承map的接口
 * 定义了两个接口方法
 */
public interface BoxIf2 extends Map<Integer, String> {

    String get(int key);

    String get(Integer key);

}

四、kotlin实现三接口

package cn.kotliner.kotlin.box

import cn.kotliner.java.box.BoxIf1
import cn.kotliner.java.box.BoxIf2

/**
 * Created by wangdong
 * 因为一个是map的get,一个是BoxIf2的get,BoxImpl2在实现他们,重载的时候他们是相互冲突的
 * 所以这个是不行的
 */
class BoxImpl2: BoxIf2 {
    override val size: Int
        get() = TODO("not implemented") //To change initializer of created properties use File | Settings | File Templates.

    override fun containsKey(key: Int?): Boolean {
        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
    }

    override fun containsValue(value: String?): Boolean {
        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
    }

    //这个是永远都会和下一个方法冲突
    override fun get(key: Int): String? {
        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
    }

    //冲突
    override operator fun get(key: Int): String? {
        return "Hello"
    }

    override fun isEmpty(): Boolean {
        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
    }
    override val entries: MutableSet<MutableMap.MutableEntry<Int, String>>
        get() = TODO("not implemented") //To change initializer of created properties use File | Settings | File Templates.
    override val keys: MutableSet<Int>
        get() = TODO("not implemented") //To change initializer of created properties use File | Settings | File Templates.

    override val values: MutableCollection<String>
        get() = TODO("not implemented") //To change initializer of created properties use File | Settings | File Templates.

    override fun clear() {
        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
    }

    override fun put(key: Int?, value: String?): String? {
        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
    }

    override fun putAll(from: Map<out Int, String>) {
        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
    }

    override fun remove(key: Int?): String? {
        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
    }
}

五、如果遇见了装箱和拆箱的问题,用Java来写,规避下就好了

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