如果你正在使用DrawerLayout和ActionBarDrawerToggle，那么显示后退按钮而不是菜单按钮(反之亦然)，你需要在你的活动中添加以下代码:

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

    mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
    mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout, toolbar, R.string.application_name, R.string.application_name);
    mDrawerLayout.addDrawerListener(mDrawerToggle);

    mDrawerToggle.setHomeAsUpIndicator(R.drawable.ic_arrow_back_white_32dp);
    mDrawerToggle.setToolbarNavigationClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            onBackPressed(); // Or you can perform some other action here when Back button is clicked.
        }
    });
    mDrawerToggle.syncState();
    // ...
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    if (mDrawerToggle.onOptionsItemSelected(item))
        return true;

    switch (item.getItemId()) {
        case android.R.id.home:
            onBackPressed();
            return true;
        // ...
    }

    return super.onOptionsItemSelected(item);
}

public void showBackInToolbar(boolean isBack) {
    // Remove next line if you still want to be able to swipe to show drawer menu.
    mDrawerLayout.setDrawerLockMode(isBack ? DrawerLayout.LOCK_MODE_LOCKED_CLOSED : DrawerLayout.LOCK_MODE_UNLOCKED);
    mDrawerToggle.setDrawerIndicatorEnabled(!isBack);
    mDrawerToggle.syncState();
}

所以当你需要显示后退按钮而不是菜单按钮时，调用showBackInToolbar(true)，如果你需要菜单按钮，调用showBackInToolbar(false)。

你可以在这里生成反向箭头(ic_arrow_back_white_32dp)，在Clipart部分搜索arrow_back(使用默认的32dp和8dp填充)。只要选择你想要的颜色。

我看到了很多答案，但这是我之前没有提到的。它从API 8+工作。

public class DetailActivity extends AppCompatActivity

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

    // toolbar
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    // add back arrow to toolbar
    if (getSupportActionBar() != null){
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        getSupportActionBar().setDisplayShowHomeEnabled(true);
    }
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // handle arrow click here
    if (item.getItemId() == android.R.id.home) {
        finish(); // close this activity and return to preview activity (if there is any)
    }

    return super.onOptionsItemSelected(item);
}

简单和容易的方法显示工具栏上的返回按钮

将此代码粘贴到onCreate方法中

 if (getSupportActionBar() != null){

            getSupportActionBar().setDisplayHomeAsUpEnabled(true);
            getSupportActionBar().setDisplayShowHomeEnabled(true);
        }

将这个覆盖方法粘贴到onCreate方法之外

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    if(item.getItemId()== android.R.id.home) {

        finish();
    }
    return super.onOptionsItemSelected(item);
}

在Kotlin是这样的

private fun setupToolbar(){
    toolbar.title = getString(R.string.YOUR_TITLE)
    setSupportActionBar(toolbar)
    supportActionBar?.setDisplayHomeAsUpEnabled(true)
    supportActionBar?.setDisplayShowHomeEnabled(true)
}

// don't forget click listener for back button
override fun onSupportNavigateUp(): Boolean {
    onBackPressed()
    return true
}

MyActivity extends AppCompatActivity {

    private Toolbar toolbar;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        ...
        toolbar = (Toolbar) findViewById(R.id.my_toolbar);
        setSupportActionBar(toolbar);
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        toolbar.setNavigationOnClickListener(arrow -> onBackPressed());
    }

如果不想创建自定义工具栏，可以这样做

public class GalleryActivity extends AppCompatActivity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        ...  
        getSupportActionBar().setTitle("Select Image");
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        getSupportActionBar().setDisplayShowHomeEnabled(true);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if (item.getItemId() == android.R.id.home) {
            finish();
        }
        return super.onOptionsItemSelected(item);
    }
}                     

在你的AndroidManifest.xml中

<activity
    android:name=".GalleryActivity"
    android:theme="@style/Theme.AppCompat.Light">        
</activity>

你也可以把这个android:theme="@style/ theme . appcompat . "轻"到< application >标签，用于应用于所有活动