Android - 将 ActionBar 后退按钮切换为导航按钮 [英] Android - Switch ActionBar Back Button to Navigation Button

问题描述

我遇到了以下问题:

我知道如何设置工具栏以显示后退按钮图标而不是汉堡按钮图标.

由此:

I know how to set up a toolbar to show a back button icon instead of a burger button icon.

From this:

为此:

使用:getSupportActionBar().setDisplayHomeAsUpEnabled(true);

现在，我想做相反的操作，我想从后退按钮图标转到汉堡图标:

Now, I want to do the reverse action, I want to go from back button icon to burger icon:

到这里:

我该怎么做?

更新:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setSupportActionBar(mToolbar);
    getSupportActionBar().setDisplayShowTitleEnabled(false);
}

private void enableViews(boolean enable) {
    if(enable) {
        // Enables back button icon
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    } else {
        // TODO: Enables burger icon
    }
}

推荐答案

如果我假设您在布局中使用 android.support.v4.widget.DrawerLayout，那么这种方法可能适用于你;我只在 API 21 上测试过，但鉴于它主要使用支持库，它应该在较低或较高的目标上工作(著名的最后一句话).

If I assume you're using android.support.v4.widget.DrawerLayout in your layout, then this approach may work for you; I've only tested on API 21 but given it's mostly using the support libraries, it should work (famous last words) on lower or higher targets.

import android.support.v7.app.ActionBarDrawerToggle
import android.support.v4.widget.DrawerLayout

    ActionBarDrawerToggle mDrawerToggle;
    DrawerLayout drawerLayout;
    private boolean mToolBarNavigationListenerIsRegistered = false;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setSupportActionBar(mToolbar);
        getSupportActionBar().setDisplayShowTitleEnabled(false);
        // Get DrawerLayout ref from layout
        drawerLayout = (DrawerLayout)findViewById(R.id.drawer);
        // Initialize ActionBarDrawerToggle, which will control toggle of hamburger.
        // You set the values of R.string.open and R.string.close accordingly.
        // Also, you can implement drawer toggle listener if you want.
        mDrawerToggle = new ActionBarDrawerToggle (this, drawerLayout, mToolbar, R.string.open, R.string.close);
        // Setting the actionbarToggle to drawer layout
        drawerLayout.addDrawerListener(mDrawerToggle);
        // Calling sync state is necessary to show your hamburger icon...
        // or so I hear. Doesn't hurt including it even if you find it works
        // without it on your test device(s)
        mDrawerToggle.syncState();
    }

    /**
     * To be semantically or contextually correct, maybe change the name
     * and signature of this function to something like:
     *
     * private void showBackButton(boolean show)
     * Just a suggestion.
     */
     private void enableViews(boolean enable) {

        // To keep states of ActionBar and ActionBarDrawerToggle synchronized,
        // when you enable on one, you disable on the other.
        // And as you may notice, the order for this operation is disable first, then enable - VERY VERY IMPORTANT.
        if(enable) {
            //You may not want to open the drawer on swipe from the left in this case  
            drawerLayout.setDrawerLockMode(DrawerLayout.LOCK_MODE_LOCKED_CLOSED);
            // Remove hamburger
            mDrawerToggle.setDrawerIndicatorEnabled(false);
            // Show back button
            getSupportActionBar().setDisplayHomeAsUpEnabled(true);
            // when DrawerToggle is disabled i.e. setDrawerIndicatorEnabled(false), navigation icon
            // clicks are disabled i.e. the UP button will not work.
            // We need to add a listener, as in below, so DrawerToggle will forward
            // click events to this listener.
            if(!mToolBarNavigationListenerIsRegistered) {
                mDrawerToggle.setToolbarNavigationClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        // Doesn't have to be onBackPressed
                        onBackPressed();
                    }
                });

                mToolBarNavigationListenerIsRegistered = true;
            }

        } else {
            //You must regain the power of swipe for the drawer. 
            drawerLayout.setDrawerLockMode(DrawerLayout.LOCK_MODE_UNLOCKED);

            // Remove back button
            getSupportActionBar().setDisplayHomeAsUpEnabled(false);
            // Show hamburger 
            mDrawerToggle.setDrawerIndicatorEnabled(true);
            // Remove the/any drawer toggle listener
            mDrawerToggle.setToolbarNavigationClickListener(null);
            mToolBarNavigationListenerIsRegistered = false;
        }

        // So, one may think "Hmm why not simplify to:
        // .....
        // getSupportActionBar().setDisplayHomeAsUpEnabled(enable);
        // mDrawer.setDrawerIndicatorEnabled(!enable);
        // ......
        // To re-iterate, the order in which you enable and disable views IS important #dontSimplify.
    }

该解决方案使用 ActionBarDrawerToggle.setDrawerIndicatorEnabled 来切换汉堡包图标的可见性，使用 ActionBar.setDisplayHomeAsUpEnabled 来切换 Up 按钮的可见性，本质上利用各自的drawable资源.

The solution uses ActionBarDrawerToggle.setDrawerIndicatorEnabled to toggle the visibility of the hamburger icon and ActionBar.setDisplayHomeAsUpEnabled for visibility of the Up button, essentially making use of their respective drawable resources.

其他假设

• 您的 Activity 主题扩展了 Theme.AppCompat.Light.NoActionBar.

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