Talk is cheap

fun main() {
    println("Hello Kotlin!")
}

val result = with(obj) {
    // obj的上下文
    "value" // 返回值
}

val list = listOf("Apple", "Banana", "Orange", "Pear", "Grape")
val result = with(StringBuilder()) {
    append("Start eating fruits.\n")
    for (fruit in list) {
        append(fruit).append("\n")
    }
    append("Ate all fruits.")
    toString()
}
println(result)

val result = obj.run {
    // obj的上下文
    "value" // 返回值
}

// result == obj
val result = obj.apply {
    // 这里是obj的上下文
}

object Util {
    fun doAction() {
        println("do action")
    }
}

class Util {
    fun doAction1() {
        println("do action1")
    }
    companion object {
        fun doAction2() {
            println("do action2")
        }
    }
}

class Util {
    fun doAction1() {
        println("do action1")
    }
    
    companion object {
        @JvmStatic
        fun doAction2() {
            println("do action2")
        }
    }
}

fun doSomething() {
    println("do something")
}

fun ClassName.methodName(param1: Int, param2: Int): Int {
    return 0
}

fun String.lettersCnt(): Int {
    var cnt = 0
    // 自动拥有String实例的上下文，可以直接遍历this，this代表字符串本身
    for (char in this) {
        if (char.isLetter()) {
            cnt++
        }
    }
    return cnt
}

class Money(val value: Int) {
    
    operator fun plus(money: Money): Money {
        val sum = value + money.value
        return Money(sum)
    }
    
    operator fun plus(newValue: Int): Money {
        val sum = value + newValue
        return Money(sum)
    }
}

val money1 = Money(5)
val money2 = Money(10)
val money3 = money1 + money2
val money4 = money3 + 20
println(money3.value)
println(money4.value)

(String, Int) -> Unit

fun example(func: (String, Int) -> Unit) {
    func("hello", 123)
}

fun num1AndNum2(num1: Int, num2: Int, operation: (Int, Int) -> Int): Int {
    val result = operation(num1, num2)
    return result
}

fun main() {
    val num1 = 100
    val num2 = 80
    val result1 = num1AndNum2(num1, num2) {
        n1, n2 -> n1 + n2
    }
    val result2 = num1AndNum2(num1, num2) {
        n1, n2 -> n1 - n2
    }
    println("result1 is $result1")
    println("result2 is $result2")
}

fun StringBuilder.build(block: StringBuilder.() -> Unit): StringBuilder {
    block()
    return this
}

fun main() {
    val list = listOf("Apple", "Banana", "Orange", "Pear", "Grape")
    val result = StringBuilder().build {
        append("Start eating fruits.\n")
        for (fruit in list) {
            append(fruit).append("\n")
        }
        append("Ate all fruits.")
    }
    println(result.toString())
}

class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        // 设置应用程序的UI内容，setContent是一个高阶函数，接受一个lambda表达式作为参数
        setContent {
            // Composable函数，定义了应用程序的主题，HelloWorldTheme包含了整个UI布局
            HelloWorldTheme {
                // A surface container using the 'background' color from the theme
                // Surface 也是一个Composable 函数，它提供了一个绘制表面，用于渲染其他Composable 函数
                // fillMaxsize修饰符来填充整个屏幕，并使用了主题中定义的背景色
                Surface(
                    modifier = Modifier.fillMaxSize(),
                    color = MaterialTheme.colorScheme.background
                ) {
                    // 接收一个字符串参数，在Surface中显示一个问候语
                    Greeting("Android")
                }
            }
        }
        Log.d("MainActivity", "onCreate execute")
    }
}

// 该项目使用的Gradle插件，通过 alias 方法引入，这意味着它们的确切 ID 和版本号在 libs.versions.toml 文件中定义。
plugins {
    alias(libs.plugins.androidApplication)
    alias(libs.plugins.jetbrainsKotlinAndroid)
}

// 项目的Android配置信息
android {
    namespace = "com.hunter.helloworld"
    compileSdk = 34

    defaultConfig {
        applicationId = "com.hunter.helloworld"
        minSdk = 21
        targetSdk = 34
        versionCode = 1
        versionName = "1.0"

        testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
        vectorDrawables {
            // 在低于minSdk的版本上使用支持库来支持向量图标
            useSupportLibrary = true
        }
    }
	// 配置不同的构建类型
    buildTypes {
        // 发布版本的构建类型
        release {
            // 是否对代码进行混淆
            isMinifyEnabled = false
            proguardFiles(getDefaultProguardFile("proguard-android-optimize.txt"), "proguard-rules.pro")
        }
    }
    compileOptions {
        sourceCompatibility = JavaVersion.VERSION_1_8
        targetCompatibility = JavaVersion.VERSION_1_8
    }
    kotlinOptions {
        jvmTarget = "1.8"
    }
    buildFeatures {
        compose = true
    }
    composeOptions {
        kotlinCompilerExtensionVersion = "1.5.1"
    }
    packaging {
        resources {
            excludes += "/META-INF/{AL2.0,LGPL2.1}"
        }
    }
}
// 在 libs.versions.toml 文件中定义的依赖
dependencies {

    implementation(libs.androidx.core.ktx)
    implementation(libs.androidx.lifecycle.runtime.ktx)
    implementation(libs.androidx.activity.compose)
    implementation(platform(libs.androidx.compose.bom))
    implementation(libs.androidx.ui)
    implementation(libs.androidx.ui.graphics)
    implementation(libs.androidx.ui.tooling.preview)
    implementation(libs.androidx.material3)
    testImplementation(libs.junit)
    androidTestImplementation(libs.androidx.junit)
    androidTestImplementation(libs.androidx.espresso.core)
    androidTestImplementation(platform(libs.androidx.compose.bom))
    androidTestImplementation(libs.androidx.ui.test.junit4)
    debugImplementation(libs.androidx.ui.tooling)
    debugImplementation(libs.androidx.ui.test.manifest)
}

// gradle插件管理
pluginManagement {
    // 获取插件的仓库
    repositories {
        google {
            content {
                includeGroupByRegex("com\\.android.*")
                includeGroupByRegex("com\\.google.*")
                includeGroupByRegex("androidx.*")
            }
        }
        mavenCentral()
        gradlePluginPortal()
    }
}
// 依赖解析管理
dependencyResolutionManagement {
    // 如果在子项目中自定义了仓库，构建将失败。确保所有子项目使用统一的仓库配置，避免潜在的版本冲突或依赖解析问题。
    repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
    repositories {
        google()
        mavenCentral()
    }
}

rootProject.name = "HelloWorld"
// 包含一个名为 :app 的子项目。:app 通常指的是 Android 应用程序模块。
include(":app")

class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            ...
        }
        // 第一个参数是tag，一般传入当前类名，便于对日志进行过滤；第二个参数是msg
        Log.d("MainActivity", "onCreate execute")
    }
}

class FirstActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
    }
}

class TestActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            ActivityTestTheme {
                // A surface container using the 'background' color from the theme
                Surface(
                    modifier = Modifier.fillMaxSize(),
                    color = MaterialTheme.colorScheme.background
                ) {
                    Greeting("Android")
                }
            }
        }
    }
}

@Composable
fun Greeting(name: String, modifier: Modifier = Modifier) {
    Text(
        text = "Hello $name!",
        modifier = modifier
    )
}

@Preview(showBackground = true)
@Composable
fun GreetingPreview() {
    ActivityTestTheme {
        Greeting("Android")
    }
}

class FirstActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        // 调用 setContentView 给当前Activity加载布局，传入布局文件的id
        setContentView(R.layout.first_layout)
    }
}

import androidx.compose.material.Text
import androidx.compose.runtime.Composable

@Composable
fun Greeting(name: String, modifier: Modifier = Modifier) {
    Text(
        text = "Hello $name!",
        modifier = modifier
    )
}

@Preview(showBackground = true)
@Composable
fun GreetingPreview() {
    ActivityTestTheme {
        // A surface container using the 'background' color from the theme
        Surface(
            modifier = Modifier.fillMaxSize(),
            color = MaterialTheme.colorScheme.background
        ) {
            Greeting("Android")
        }
    }
}

class FirstActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        // 调用 setContentView 给当前Activity加载布局，传入布局文件的id
        setContentView(R.layout.first_layout)

        // 调用 findViewById 获取布局文件中定义的元素，返回一个继承自View的泛型对象
        val button1: Button = findViewById(R.id.button1)
        // 为按钮注册点击监听器
        button1.setOnClickListener {
            // 调用 makeText 创建Toast对象，再调用 show 进行展示
            Toast.makeText(this, "You clicked Button 1", Toast.LENGTH_SHORT).show()
        }
    }
}

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    // 调用first_layout.xml布局文件对应的Binding类的inflate函数加载该布局
    val binding = FirstLayoutBinding.inflate(layoutInflater)
    // 传入根元素的实例，就可以成功显示first_layout.xml这个布局的内容
    setContentView(binding.root)

    // 为按钮注册点击监听器
    binding.button1.setOnClickListener {
        // 调用 makeText 创建Toast对象，再调用 show 进行展示
        Toast.makeText(this, "You clicked Button 1", Toast.LENGTH_SHORT).show()
    }
}

override fun onCreateOptionsMenu(menu: Menu?): Boolean {
    // menuInflater是语法糖，实际调用了父类的getMenuInflater方法，能够得到一个MenuInflater对象
    // 调用其inflate方法就可以给当前Activity创建菜单。
    menuInflater.inflate(R.menu.main, menu)
    // 允许创建的菜单显示
    return true
}

// 定义菜单响应事件
override fun onOptionsItemSelected(item: MenuItem): Boolean {
    when (item.itemId) {
        R.id.add_item -> Toast.makeText(
            this, "You clicked Add", Toast.LENGTH_SHORT
        ).show()
        R.id.remove_item -> Toast.makeText(
            this, "You clicked Remove", Toast.LENGTH_SHORT
        ).show()
    }
    // 消费掉这个点击事件，系统不会进一步传递或处理
    return true
}

// 为按钮注册点击监听器
binding.button1.setOnClickListener {
    // 点击按钮，当前的Activity就会被销毁
    finish()
}

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.second_layout)
}

// 为按钮注册点击监听器
binding.button1.setOnClickListener {
    // 在当前上下文的基础上，打开SecondActivity
    val intent = Intent(this, SecondActivity::class.java)
    // 执行该intent
    startActivity(intent)
}

// 为按钮注册点击监听器
binding.button1.setOnClickListener {
    // 在当前上下文的基础上，打开指定的action能对应的activity
    val intent = Intent("com.hunter.myapplication.ACTION_START")
    // 指定category
    intent.addCategory("com.hunter.myapplication.MY_CATEGORY")
    // 执行该intent
    startActivity(intent)
}

// 为按钮注册点击监听器
binding.button1.setOnClickListener {
    // 在当前上下文的基础上，打开指定的action能对应的activity，ACTION_VIEW是android内置的动作
    val intent = Intent(Intent.ACTION_VIEW)
    intent.data = Uri.parse("https://www.bing.com")
    startActivity(intent)
}

// 为按钮注册点击监听器
binding.button1.setOnClickListener {
    val intent = Intent(Intent.ACTION_DIAL)
    intent.data = Uri.parse("tel:10086")
    startActivity(intent)
}

// 为按钮注册点击监听器
binding.button1.setOnClickListener {
    val data = "Hello SecondActivity"
    val intent = Intent(this, SecondActivity::class.java)
    // 通过putExtra方法传递一个字符串
    intent.putExtra("extra_data", data)
    startActivity(intent)
}

val stringExtraData = intent.getStringExtra("extra_data")
Log.d("SecondActivity", "extra data is $stringExtraData")

class FirstActivity : AppCompatActivity() {
    // 定义 ActivityResultLauncher，registerForActivityResult用于处理活动结果的注册
    private val resultLauncher = registerForActivityResult(
        // 这个 resultLauncher 将用于启动一个新活动并接收其结果
        ActivityResultContracts.StartActivityForResult()
    ) { result ->
       if (result.resultCode == RESULT_OK) {
           val data: Intent? = result.data
           // 处理返回的数据，?用于安全地操作可能的空值
           val returnedData = data?.getStringExtra("data_return")
           Log.d("FirstActivity", "returned data is $returnedData")
       }
      }
    ...
    override fun onCreate(savedInstanceState: Bundle?) {
        ...

        // 为按钮注册点击监听器
        binding.button1.setOnClickListener {
            val intent = Intent(this, SecondActivity::class.java)
            // 启动SecondActivity，并等待结果
            resultLauncher.launch(intent)
        }
    }
}

class SecondActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        // 调用second_layout.xml布局文件对应的Binding类的inflate函数加载该布局
        val binding = SecondLayoutBinding.inflate(layoutInflater)
        // 传入根元素的实例，就可以成功显示second_layout.xml这个布局的内容
        setContentView(binding.root)

        // 为 button2 注册点击监听器
        binding.button2.setOnClickListener {
            returnDataToFirstActivity()
        }

        // 注册 OnBackPressedCallback 来处理后退按钮事件
        onBackPressedDispatcher.addCallback(this, object : OnBackPressedCallback(true) {
            override fun handleOnBackPressed() {
                returnDataToFirstActivity()
            }
        })
    }

    private fun returnDataToFirstActivity() {
        val intent = Intent()
        intent.putExtra("data_return", "Hello FirstActivity")
        // setResult 专门用于向上一个Activity返回数据
        setResult(RESULT_OK, intent)
        finish()
    }
}

class NormalActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.normal_layout)
    }
}

class DialogActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.dialog_layout)
    }
}

class MainActivity : AppCompatActivity() {
    private val tag = "MainActivity"

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        Log.d(tag, "onCreate")
        // 调用activity_main.xml布局文件对应的Binding类的inflate函数加载布局
        val binding = ActivityMainBinding.inflate(layoutInflater)
        // 传入根元素的实例，就可以成功显示activity_main.xml这个布局的内容
        setContentView(binding.root)

        binding.startNormalActivity.setOnClickListener {
            val intent = Intent(this, NormalActivity::class.java)
            startActivity(intent)
        }

        binding.startDialogActivity.setOnClickListener {
            val intent = Intent(this, DialogActivity::class.java)
            startActivity(intent)
        }
    }

    override fun onStart() {
        super.onStart()
        Log.d(tag, "onStart")
    }

    override fun onResume() {
        super.onResume()
        Log.d(tag, "onResume")
    }

    override fun onPause() {
        super.onPause()
        Log.d(tag, "onPause")
    }

    override fun onStop() {
        super.onStop()
        Log.d(tag, "onStop")
    }

    override fun onDestroy() {
        super.onDestroy()
        Log.d(tag, "onDestroy")
    }

    override fun onRestart() {
        super.onRestart()
        Log.d(tag, "onRestart")
    }
}

override fun onSaveInstanceState(outState: Bundle) {
    super.onSaveInstanceState(outState)
    val tempData = "Something you just typed"
    outState.putString("data_key", tempData)
}

override fun onCreate(savedInstanceState: Bundle?) {
	...
    if (savedInstanceState != null) {
        val tempData = savedInstanceState.getString("data_key")
        Log.d(tag, "tempData is $tempData")
    }
}

open class BaseActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        // javaClass相当于在java中调用getClass()方法，获取实例的class对象，调用simpleName获取当前实例的类名
        Log.d("BaseActivity", javaClass.simpleName)
    }
}

/**
 * Object: 单例类
 * 使用单例类是因为全局只需要一个Activity集合
 */
object ActivityCollector {
    // 通过ArrayList暂存Activity
    private val activities = ArrayList<Activity>()

    fun addActivity(activity: Activity) {
        activities.add(activity)
    }

    fun removeActivity(activity: Activity) {
        activities.remove(activity)
    }

    /**
     * 将ArrayList中存储的Activity全部销毁
     */
    fun finishAll() {
        for (activity in activities) {
            // 是否正在销毁中
            if (!activity.isFinishing) {
                activity.finish()
            }
        }
        activities.clear()
    }
}

open class BaseActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        // javaClass相当于在java中调用getClass()方法，获取实例的class对象，调用simpleName获取当前实例的类名
        Log.d("BaseActivity", javaClass.simpleName)
        ActivityCollector.addActivity(this)
    }

    override fun onDestroy() {
        super.onDestroy()
        ActivityCollector.removeActivity(this)
    }
}

class ThirdActivity : BaseActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        Log.d("ThirdActivity", "Task id is $taskId")
        // 调用third_layout.xml布局文件对应的Binding类的inflate函数加载该布局
        val binding =  ThirdLayoutBinding.inflate(layoutInflater)
        // 传入根元素的实例，就可以成功显示third_layout.xml这个布局的内容
        setContentView(binding.root)

        binding.button3.setOnClickListener {
            ActivityCollector.finishAll()
            // 杀掉当前进程，以保证程序完全退出，killProcess只能用于杀掉当前程序的进程，不能杀掉其他程序
            android.os.Process.killProcess(android.os.Process.myPid())
        }
    }
}

val intent = Intent(this, SecondActivity::class.java)
intent.putExtra("param1", "data1")
intent.putExtra("param2", "data2")
startActivity(intent)

class SecondActivity : BaseActivity() {
    ...
    companion object {
        fun actionStart(context: Context, data1: String, data2: String) {
            val intent = Intent(context, SecondActivity::class.java).apply {
                putExtra("param1", data1)
                putExtra("param2", data2)
            }
            context.startActivity(intent)
        }
    }
}

button1.setOnClickListener {
    SecondActivity.actionStart(this, "data1", "data2")
}

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)

    val binding = ActivityMainBinding.inflate(layoutInflater)
    setContentView(binding.root)

    binding.button.setOnClickListener {
		// 添加逻辑
    }
}

class MainActivity : AppCompatActivity(), View.OnClickListener {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        val binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)

        binding.button.setOnClickListener(this)
    }

    override fun onClick(v: View?) {
        when (v?.id) {
            R.id.button -> {
                // 添加逻辑
            }
        }
    }
}

class MainActivity : AppCompatActivity(), View.OnClickListener {
    private lateinit var binding: ActivityMainBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)

        binding.button.setOnClickListener(this)
    }

    override fun onClick(v: View?) {
        when (v?.id) {
            R.id.button -> {
                val inputText = binding.editText.text.toString()
                Toast.makeText(this, inputText, Toast.LENGTH_SHORT).show()
            }
        }
    }
}

class MainActivity : AppCompatActivity(), View.OnClickListener {
    private lateinit var binding: ActivityMainBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)

        binding.button.setOnClickListener(this)
    }

    override fun onClick(v: View?) {
        when (v?.id) {
            ...
                binding.imageView.setImageResource(R.drawable.cy1a9740)
            }
        }
    }
}

class MainActivity : AppCompatActivity(), View.OnClickListener {
    private lateinit var binding: ActivityMainBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)

        binding.button.setOnClickListener(this)
    }

    override fun onClick(v: View?) {
        when (v?.id) {
            R.id.button -> {
                // 点击让进度条消失，再点击让进度条出现
                if (binding.progressBar.visibility == View.VISIBLE) {
                    binding.progressBar.visibility = View.GONE
                } else {
                    binding.progressBar.visibility = View.VISIBLE
                }
            }
        }
    }
}

class MainActivity : AppCompatActivity(), View.OnClickListener {
    private lateinit var binding: ActivityMainBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)

        binding.button.setOnClickListener(this)
    }

    override fun onClick(v: View?) {
        when (v?.id) {
            R.id.button -> {
                // 在当前进度上加10
                binding.progressBar.progress += 10
            }
        }
    }
}

class MainActivity : AppCompatActivity(), View.OnClickListener {
    private lateinit var binding: ActivityMainBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)

        binding.button.setOnClickListener(this)
    }

    override fun onClick(v: View?) {
        when (v?.id) {
            R.id.button -> {
                // 构建对话框
                AlertDialog.Builder(this).apply {
                    setTitle("This is Dialog") // 设置标题
                    setMessage("Something important.") // 设置内容
                    setCancelable(false) // 能否使用Back键关闭对话框
                    // 设置确定按钮的点击事件
                    setPositiveButton("OK") { _, _ -> // 目前没有具体的处理逻辑
                                            }
                    // 设置取消按钮的点击事件
                    setNegativeButton("Cancel") { _, _ ->
                                                }
                    show() // 显示对话框
                }
            }
        }
    }