为什么工具栏中的后退箭头未显示? [英] Why is the back arrow in the toolbar not shown?
问题描述
我的问题与android工具栏有关.我想激活后退箭头,回到主菜单.我使用了表达式getSupportActionButton.setDisplayHomeAsUpEnabled(true)
.当我测试该应用程序时,未显示箭头.我找不到任何解决方案来解决我的问题.使用getSupportActionButton.setDefaultDisplayHomeAsUpEnabled(true)
表达式时,出现错误
My Problem is about the android toolbar. I want to activate the back arrow, to go back to the main menu. I used the expression getSupportActionButton.setDisplayHomeAsUpEnabled(true)
. When I tested the app, the arrow was not shown. I couldn't find any solutions to solve my problem. When I used the getSupportActionButton.setDefaultDisplayHomeAsUpEnabled(true)
-expression, I got the error
只能从同一库组(groupId = com.android.support)中调用ActionBar.setDefaultDisplayHomeAsUpEnabled".
ActionBar.setDefaultDisplayHomeAsUpEnabled can only be called from within the same library group (groupId=com.android.support)".
package de.julius.antgo2;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Button;
public class calendar extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_calendar);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
getSupportActionBar().setTitle(null);
if(getSupportActionBar() != null){
getSupportActionBar().setTitle("Test");
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setDisplayShowHomeEnabled(true);
}
}
}
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@drawable/apppagebackground"
android:theme="@style/AppTheme"
tools:context=".calendar">
<include
android:id="@+id/toolbar"
layout="@layout/toolbar"/>
<LinearLayout
android:background="#ffffff"
android:layout_centerHorizontal="true"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<CalendarView
android:layout_width="match_parent"
android:layout_height="match_parent"></CalendarView>
</LinearLayout>
</RelativeLayout>
推荐答案
如果您使用的是
NoActionBar
主题,请在其中创建一个工具栏 布局文件.我正在使用新设计支持库的材料组件主题.
If you are using
NoActionBar
theme then create a toolbar inside layout file. I am using material component theme of new design support library.
布局文件:
<com.google.android.material.appbar.AppBarLayout
android:id="@+id/AppBar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:fitsSystemWindows="true"
android:theme="@style/AppTheme.AppBarOverlay">
<androidx.appcompat.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
app:layout_scrollFlags="scroll|enterAlways"
app:popupTheme="@style/AppTheme.PopupOverlay"/>
</com.google.android.material.appbar.AppBarLayout>
样式:
<style name="AppTheme" parent="Theme.MaterialComponents.Light.DarkActionBar" />
<style name="AppTheme.AppBarOverlay" parent="ThemeOverlay.MaterialComponents.Dark" />
<style name="AppTheme.PopupOverlay" parent="ThemeOverlay.MaterialComponents.Light" />
Java文件:
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
toolbar.setTitle("Title");
if (getSupportActionBar() != null) {
getSupportActionBar().setHomeButtonEnabled(true);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
}
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