62 lines
1.6 KiB
Markdown
62 lines
1.6 KiB
Markdown
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# Kotlin 操作Layout控件
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在Android Acitivity开发中，传统的java开发中findviewbyid。在kotlin中，有两种写法都可以操作layout控件。
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## 一、传统写法（不推荐）
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不推荐的原因主要是麻烦，满屏幕都是findViewById，非常的繁琐。
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```kotlin
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package com.geek.motion
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import androidx.appcompat.app.AppCompatActivity
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import android.os.Bundle
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import android.widget.TextView
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class MainActivity : AppCompatActivity() {
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override fun onCreate(savedInstanceState: Bundle?) {
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super.onCreate(savedInstanceState)
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setContentView(R.layout.activity_main)
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var textView = findViewById<TextView>(R.id.textView)
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textView.setText("Hello Kotlin")
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}
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}
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```
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## 二、省略写法(推荐)
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下面采用的是省略写法，注意需要引入import kotlinx.android.synthetic.main.activity_main.*
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```kotlin
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package com.geek.motion
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import androidx.appcompat.app.AppCompatActivity
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import android.os.Bundle
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import kotlinx.android.synthetic.main.activity_main.*
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class MainActivity : AppCompatActivity() {
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override fun onCreate(savedInstanceState: Bundle?) {
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super.onCreate(savedInstanceState)
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setContentView(R.layout.activity_main)
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textView.text = "Hello kotlin"
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}
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}
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```
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如果在引用import kotlinx.android.synthetic.main.activity_main.*时报错，注意在build.gradle中，添加：**'kotlin-android-extensions'**
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```shell
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plugins {
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id 'com.android.application'
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id 'org.jetbrains.kotlin.android'
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// 添加
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id 'kotlin-android-extensions'
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}
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android {
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compileSdk 32
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...
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```
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