java - 处理android中的后退按钮操作

Question

我有 1 个活动。在该活动中，我有 4 个片段。如果我在这些片段之间切换，我想处理我的回溯。如果我在任何片段中，我必须按一次后退按钮直接进入主要活动。一旦我到达家庭活动，如果我再次按下后退按钮，活动应该被关闭。

以下是我的家庭活动

package com.fuzail.my_app.DatabaseSQLite;

import android.app.DatePickerDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.support.design.widget.NavigationView;
import android.support.v4.app.Fragment;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBar;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.DatePicker;
import android.widget.ImageButton;
import android.widget.TextView;


import com.fuzail.my_app.R;

import java.util.ArrayList;
import java.util.Calendar;

import static android.content.DialogInterface.BUTTON_NEGATIVE;
import static android.content.DialogInterface.BUTTON_POSITIVE;
import static com.fuzail.my_app.Constant.NO;
import static com.fuzail.my_app.Constant.YES;

public class MaccabiDrawerHome extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener,DialogInterface.OnClickListener {
    private DrawerLayout mDrawer;
    private Toolbar toolbar;
    private Menu menu;
    NavigationView navView;
    private ArrayList<UserModel> list = new ArrayList<UserModel>();
    private int currentYear, currentMonth, currentDay;
    private SharedPreferenceMaccabi mSharedPreference;

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

        Fragment fragment = new FragViewProfile();
        getSupportFragmentManager().beginTransaction().
                add(R.id.content_frame, fragment).
                commit();

        // Set a Toolbar to replace the ActionBar.
        toolbar = (Toolbar) findViewById(R.id.macaabi_myprofile_toolbar);
        setSupportActionBar(toolbar);
        setSupportActionBar(toolbar);
        ActionBar actionBar = getSupportActionBar();
        actionBar.setDisplayShowTitleEnabled(false);
        toolbar.setNavigationIcon(R.drawable.ic_maccabi_menu);
        toolbar.setTitle("My Profile");
        // Find our drawer view
        mDrawer = (DrawerLayout) findViewById(R.id.drawer_maccabi);
        navView = findViewById(R.id.maccabi_navigation);
        navView.setNavigationItemSelectedListener(this);
        mSharedPreference = SharedPreferenceMaccabi.getInstance(this);

    }

    @Override
    public void onBackPressed() {
        Intent i = new Intent(this, MaccabiDrawerHome.class);

        FragViewProfile test = (FragViewProfile) getSupportFragmentManager().findFragmentById(R.id.content_frame);

        if (test != null && test.isVisible()) {
            finish();
        }
        else {
            startActivity(i);
        }

    }


    @Override
    public boolean onNavigationItemSelected(MenuItem item) {
        // Handle navigation view item clicks here.
        int id = item.getItemId();
        String title = "";
        Fragment fragment = null;
        switch (id) {
            case R.id.mallmemb:
                fragment = new FragAllMembers();
                toolbar.setTitle("All Members");
                menu.findItem(R.id.item_cal).setVisible(false);
                menu.findItem(R.id.item_edit).setVisible(false);
                break;
            case R.id.mlikes:
                fragment = new FragLikes();
                ((FragLikes) fragment).getAllLikedByData(list);
                toolbar.setTitle("likes");
                menu.findItem(R.id.item_cal).setVisible(false);
                menu.findItem(R.id.item_edit).setVisible(false);
                break;
            case R.id.mlogout:
                AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(MaccabiDrawerHome.this);
                alertDialogBuilder.setTitle("Logout");
                alertDialogBuilder.setMessage("Are you sure you want to logout");
                alertDialogBuilder.setCancelable(false);

                alertDialogBuilder.setPositiveButton("YES", this);
                alertDialogBuilder.setNegativeButton("NO", this);

                AlertDialog alertDialog = alertDialogBuilder.create();
                alertDialog.show();


                return true;
        }
        if (fragment != null) {
            getSupportFragmentManager().beginTransaction().
                    replace(R.id.content_frame, fragment).
                    commit();
            getSupportActionBar().setTitle(title);
            mDrawer.closeDrawers();
            return true;
        }

        return false;
    }

    @Override
    public void onClick(DialogInterface dialog, int which) {

        switch (which) {
            case BUTTON_POSITIVE:
                mSharedPreference.clearData();
                startActivity(new Intent(MaccabiDrawerHome.this, MacaabiEmailHome.class));
                break;

            case BUTTON_NEGATIVE:
                dialog.dismiss();
                break;
        }

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        this.menu = menu;
        getMenuInflater().inflate(R.menu.menutoolbar, menu);
        return true;

    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {

        switch (item.getItemId()) {
            case android.R.id.home:
                mDrawer.openDrawer(GravityCompat.START);
                return true;

            case R.id.item_edit:
                menu.findItem(R.id.item_edit).setVisible(false);
                menu.findItem(R.id.item_cal).setVisible(true);
                toolbar.setTitle("Edit Profile");
                getSupportFragmentManager().beginTransaction().replace(R.id.content_frame, new FragEditProfile()).commit();
                return true;

            case R.id.item_cal:
                DatePickerDialog datePickerDialog = new DatePickerDialog(this, new DatePickerDialog.OnDateSetListener() {
                    @Override
                    public void onDateSet(DatePicker view, int year, int month, int dayOfMonth) {
                        populateSetDate(year, month + 1, dayOfMonth);
                    }
                }, currentYear, currentMonth, currentDay);
                Calendar calendar = Calendar.getInstance();
                calendar.add(Calendar.YEAR, currentYear - 4);
                calendar.add(Calendar.MONTH, currentMonth);
                datePickerDialog.getDatePicker().setMaxDate(calendar.getTimeInMillis());

                datePickerDialog.setCancelable(false);
                datePickerDialog.show();
                return true;
        }
        return super.onOptionsItemSelected(item);
    }

    @Override
    public boolean onPrepareOptionsMenu(Menu menu) {
        return super.onPrepareOptionsMenu(menu);
    }


    /* populateSetDate method is used
       to display the data in a textView
       in edit profile fragment*/

    public void populateSetDate(int year, int month, int day) {
        TextView dob = (TextView) findViewById(R.id.dob);
        dob.setText(month + "/" + day + "/" + year);


        String a1 = getAge(year, month, day);
        TextView agess = (TextView) findViewById(R.id.age);
        agess.setText(a1);
    }

    /* getAge method is used to calculate
       the age and then store in a textView
       in edit profile fragment*/

    private String getAge(int year, int month, int day) {
        Calendar dob = Calendar.getInstance();
        Calendar today = Calendar.getInstance();

        dob.set(year, month, day);

        int age = today.get(Calendar.YEAR) - dob.get(Calendar.YEAR);

        if (today.get(Calendar.DAY_OF_YEAR) < dob.get(Calendar.DAY_OF_YEAR)) {
            age--;
        }

        Integer ageInt = new Integer(age);
        String ageS = ageInt.toString();
        Log.d("age", "getAge: " + ageS);
        return ageS;

    }
    public  void  newcountFrag(){
        Fragment fragment;
        fragment = new FragLikes();
        toolbar.setTitle("likes");
        menu.findItem(R.id.item_cal).setVisible(false);
        menu.findItem(R.id.item_edit).setVisible(false);
        getSupportFragmentManager().beginTransaction().replace(R.id.content_frame, new FragLikes()).commit();

    }
}

标签： javaandroidandroid-fragments

Answer 1

您可以覆盖onBackPressed()活动和片段中可用的方法以更改默认行为。并不是一开始就为片段调用它，只有当它返回 false 时才转到活动方法。