androidx.fragment.app.Fragment 无法转换为 android.app.Fragment

Question

我有一个片段文件。有一条错误信息

"error: incompatible types: androidx.fragment.app.Fragment cannot be converted to android.app.Fragment. fragmentTransaction.replace(R.id.frame_layout, fragment).addToBackStack(null);"

我知道我的 build.gradle 文件有问题，但我不知道应该使用哪个依赖项。我已经阅读了相关的文档和问题，但不推荐使用某些依赖项。这是我的 MainActivity 文件：

package com.example.notesapp;

import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.Fragment;

import android.annotation.SuppressLint;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.os.Bundle;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        replaceFragment(HomeFragment.newInstance(), true);
    }

    @SuppressLint("ResourceType")
    public void replaceFragment(Fragment fragment, Boolean istransition){
        FragmentManager fragmentManager = getFragmentManager();
        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();

        if(istransition) {
            fragmentTransaction.setCustomAnimations(android.R.anim.slide_out_right, android.R.anim.slide_in_left);
        }

        fragmentTransaction.replace(R.id.frame_layout, fragment).addToBackStack(null);
    }
}

这是我的 build.gradle 文件

plugins {
    id 'com.android.application'
}

android {
    compileSdkVersion 30
    buildToolsVersion "30.0.3"

    defaultConfig {
        applicationId "com.example.notesapp"
        minSdkVersion 16
        targetSdkVersion 30
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
}

dependencies {

    implementation 'androidx.appcompat:appcompat:1.2.0'
    implementation 'com.google.android.material:material:1.2.1'
    implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
    implementation 'androidx.legacy:legacy-support-v4:1.0.0'
    testImplementation 'junit:junit:4.+'
    androidTestImplementation 'androidx.test.ext:junit:1.1.2'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.3.0'

    //material design
    implementation 'com.google.android.material:material:1.2.1'

    //circle image view
    implementation 'de.hdodenhof:circleimageview:3.1.0'

    //scalable unit text size
    implementation 'com.intuit.ssp:ssp-android:1.0.6'

    //scalable unit size
    implementation 'com.intuit.sdp:sdp-android:1.0.6'

    //room database
    implementation 'androidx.room:room-runtime:2.2.5'
    annotationProcessor 'androidx.room:room-compiler:2.2.5'

    implementation 'com.intuit.ssp:ssp-android:1.0.6'

}

谢谢

Answer 1

使用

import androidx.fragment.app.FragmentManager;
import androidx.fragment.app.FragmentTransaction

而不是

import android.app.FragmentManager;
import android.app.FragmentTransaction;

Answer 2

问题是什么是 HomeFragment - 它扩展了内置的 Fragment 或 androidx 版本？它应该扩展 androidx 版本。然后你必须使用 getSupportFragmentManager

FragmentManager fragmentManager = getSupportFragmentManager();

那么你的 IDE 应该建议你修复导入，甚至会为你做 - 不应该使用任何 android.app.Fragment... 导入，只有 androidx.fragment... lines/packages

androidx.fragment.app.Fragment 无法转换为 android.app.Fragment

androidx.fragment.app.Fragment cannot be converted to android.app.Fragment

dependencies

android

fragment

android-fragments

android-studio