我无法解决错误的问题:
incompatible types: no unique maximal instance exists for type variable T with upper bounds com.velocat.cmap.Preference,androidx.preference.Preference
Preference preference = findPreference("button");
^
where T is a type-variable:
T extends androidx.preference.Preference declared in method <T>findPreference(CharSequence)
SettingsFragment.java
import android.os.Bundle;
import android.preference.Preference;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import androidx.preference.PreferenceFragmentCompat;
public class SettingsFragmentActivity extends PreferenceFragmentCompat {
Preference preference;
@Override
public void onCreatePreferences(Bundle savedInstanceState, String rootKey) {
addPreferencesFromResource(R.xml.setting);
Preference preference = findPreference("preference1");
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = super.onCreateView(inflater, container, savedInstanceState);
return view;
}
}
buld.gradle]的一部分]
dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation 'androidx.appcompat:appcompat:1.1.0' implementation 'androidx.legacy:legacy-support-v4:1.0.0' implementation 'com.google.android.material:material:1.0.0' implementation 'androidx.constraintlayout:constraintlayout:1.1.3' implementation 'androidx.navigation:navigation-fragment:2.1.0' implementation 'androidx.navigation:navigation-ui:2.1.0' implementation 'com.google.android.gms:play-services-location:17.0.0' testImplementation 'junit:junit:4.12' androidTestImplementation 'androidx.test.ext:junit:1.1.1' androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0' implementation 'androidx.preference:preference:1.1.0' }
xml / settings.xml
<?xml version="1.0" encoding="utf-8"?> <PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android" > <SwitchPreference android:defaultValue="false" android:key="preference1" android:title="test" /> </PreferenceScreen>
我重新阅读了搜索中的所有内容,但没有找到解决问题的方法。有谁知道如何摆脱这个错误?
感谢您对此主题的任何澄清。
我无法解决以下错误的问题:不兼容的类型:类型变量T的上限com.velocat.cmap.Preference,androidx.preference.Preference ...不存在唯一的最大实例。]
Preference
应该是