在Android Studio中为Fragment添加页面标题与返回按钮

如何将应用标题替换为“About”，并添加返回箭头以使用户能回到上一界面？

提供的代码 #

import android.content.Context;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.Fragment;
import com.milople.fajralarm.R;
import java.util.Objects;

public class AboutFragment extends Fragment {
    TextView lbllink;
    View view;
    Context ctx;
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        ctx=getActivity();
        view= inflater.inflate(R.layout.fragment_about, container, false);
        lbllink=view.findViewById(R.id.lbllink);
        lbllink.setOnClickListener(v -> {
            Intent intent=new Intent(Intent.ACTION_VIEW, Uri.parse("https://thehalallife.co.uk/"));
            startActivity(intent);
        });
        Objects.requireNonNull(((AppCompatActivity) requireActivity()).getSupportActionBar()).setSubtitle("");
        return view;
    }
}

UI截图 #

1. 修改标题为“About” #

在onCreateView方法中，通过ActionBar的setTitle方法直接替换标题。

2. 添加返回箭头并实现返回功能 #

调用setDisplayHomeAsUpEnabled(true)显示返回箭头，同时重写菜单事件处理方法，响应箭头点击回到上一界面。

修改后的完整代码 #

import android.content.Context;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.Fragment;
import com.milople.fajralarm.R;
import java.util.Objects;

public class AboutFragment extends Fragment {
    TextView lbllink;
    View view;
    Context ctx;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // 声明Fragment需要处理菜单事件
        setHasOptionsMenu(true);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        ctx=getActivity();
        view= inflater.inflate(R.layout.fragment_about, container, false);
        lbllink=view.findViewById(R.id.lbllink);
        lbllink.setOnClickListener(v -> {
            Intent intent=new Intent(Intent.ACTION_VIEW, Uri.parse("https://thehalallife.co.uk/"));
            startActivity(intent);
        });
        
        // 配置ActionBar：修改标题、显示返回箭头、清空副标题
        AppCompatActivity activity = (AppCompatActivity) requireActivity();
        Objects.requireNonNull(activity.getSupportActionBar()).setTitle("About");
        Objects.requireNonNull(activity.getSupportActionBar()).setDisplayHomeAsUpEnabled(true);
        Objects.requireNonNull(activity.getSupportActionBar()).setSubtitle("");
        
        return view;
    }

    // 处理返回箭头点击事件
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if (item.getItemId() == android.R.id.home) {
            requireActivity().onBackPressed();
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

补充说明 #

如果宿主Activity已经统一处理了返回逻辑，也可以不在Fragment中重写onOptionsItemSelected，只需在Activity中添加以下代码即可：

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

内容的提问来源于stack exchange，提问作者james