【Android】创建带参数的 Fragment

在 Android 中，严禁通过构造函数给 Fragment 传参。因为当系统因配置变化（如旋转屏幕）或内存回收后重建 Fragment 时，只会调用无参构造函数，导致你通过构造函数传入的参数全部丢失。

1、添加依赖库

kotlin 复制代码

dependencies {
    ...
    // Kotlin
    implementation("androidx.fragment:fragment-ktx:1.8.9")
}

2、创建Fragment

通过 Bundle + setArguments() 来传递参数。

kotlin 复制代码

package com.android.designui.fragmentnav

import android.graphics.BitmapFactory
import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.fragment.app.Fragment
import com.android.designui.databinding.FragmentSwiperImageBinding

class SwiperImageFragment: Fragment() {

    companion object {
        private const val ARG_PATH = "arg_path"

        // 工厂方法：创建带参数的Fragment实例
        fun newInstance(path: String): SwiperImageFragment {
            val fragment = SwiperImageFragment()
            val args = Bundle().apply {
                putString(ARG_PATH, path)
            }
            fragment.arguments = args
            return fragment
        }
    }

    private lateinit var viewBinding: FragmentSwiperImageBinding
    private var path: String? = null

    override fun onCreate(savedInstanceState: Bundle?) {    
        super.onCreate(savedInstanceState)
        // 获取创建Fragment时传入的参数
        arguments?.let {
            path = arguments?.getString(ARG_PATH)
        }
    }

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View {
        viewBinding = FragmentSwiperImageBinding.inflate(inflater, container, false)
        return viewBinding.root
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        // 将图片添加到 ImageView 控件上
        path?.let {
            val inputStream = context?.assets?.open(it)
            val bitmap = BitmapFactory.decodeStream(inputStream)
            viewBinding.image.setImageBitmap(bitmap)
            inputStream?.close()
        }
    }
}

3、打开Fragment

cpp 复制代码

SwiperImageFragment.newInstance("images/1.jpg")