Android学习--Fragment，Android实习面试经验汇总

2023-10-26 17:02:16

import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.fragment.app.Fragment

class AntherRightFrogment :Fragment() {
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.anther_right_fragement,container,false)
}
}

然后修改man.xml代码，引入FrameLayout布局，把右边的Fragment布局替换

<?xml version="1.0" encoding="utf-8"?>

最后我们修改ManActivity的代码，为button设置监听器，达到点击BUTTON按钮，更换Fragment

class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val button:Button=findViewById(R.id.button)
button.setOnClickListener{
repalce(AntherRightFrogment())
}
repalce(RightFragment())
}
private fun repalce(fragment:Fragment){
//就是获取所在fragment的父容器的管理器，
val fragementManager=supportFragmentManager
//开启一个事务
val transaction=fragementManager.beginTransaction()
//添加和替换Fragment
transaction.replace(R.id.rightFragment,fragment)
//返回栈
transaction.addToBackStack(null)
//提交事务
transaction.commit()

}

在Fragment中实现返回栈

按下back建返回上一个Fragment

//返回栈
transaction.addToBackStack(null)

Fragment生命周期

onAttach()：Fragment和Activity相关联时调用

onCreate()：系统创建Fragment时调用

onCreateView()：创建Fragment的布局（视图）调用

onActivityCreated()：确保与Fragment相关联的Activity调用完时调用

首先我们修改RightFragment代码来看效果

package com.example.fragmenttest

import android.content.Context
import android.os.Bundle
import android.util.Log
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.fragment.app.Fragment

class RightFragment :Fragment(){
companion object{
const val TAG=“RightFragment”
}
//当Fragment和Activity建立关联时调用
override fun onAttach(context: Context) {
super.onAttach(context)
Log.d(TAG,“onAttach”)
}

override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
Log.d(TAG,“onCteate”)
}
//为Fragment创建视图获加载布局时调用
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
Log.d(TAG,“onCreateView”)
return inflater.inflate(R.layout.right_fragment,container,false)
}
//确保和Fragment相关联的Activity已经创建完毕时候调用
override fun onActivityCreated(savedInstanceState: Bundle?) {
super.onActivityCreated(savedInstanceState)

Log.d(TAG,“onActivityCreated”)
}

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”)
}
//当与Fragment先关联的视图移除时候调用
override fun onDestroyView() {
super.onDestroyView()
Log.d(TAG,“onDestroyView”)
}

override fun onDestroy() {
super.onDestroy()
Log.d(TAG,“onDestroy”)
}
//当Fragment与Activity解除关联时候调用
override fun onDetach() {
super.onDetach()
Log.d(TAG,“onDetach”)
}

}

首次加载RightFragment