Android开发学习教程（22）- Intent传值与startActivityForResult返回值
2023-01-28 14:55 作者:ChatGPT云炬学长 | 我要投稿
—— 你要悄悄拔尖，然后一鸣惊人。
上一篇我们讲了Intent的基本概念，现在我们通过一个实例来验证。
Intent传值
有这么一个场景，用户在登录页面输入用户名之后点击登录，跳转到另一个页面显示用户名名称。这个场景就是典型的Activity间Intent传值。下面我们开始编写代码：
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public class LoginActivity extends AppCompatActivity { private EditText etUsername; private Button btnLogin; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_login); initView(); } private void initView() { etUsername = findViewById(R.id.et_username); btnLogin = findViewById(R.id.btn_login); btnLogin.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { Intent intent = new Intent(LoginActivity.this, MainActivity.class); intent.putExtra("username", etUsername.getText().toString()); startActivity(intent); } }); }}1
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public class MainActivity extends AppCompatActivity { private TextView tvUsername; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); initView(); } private void initView() { tvUsername = findViewById(R.id.tv_username); tvUsername.setText("欢迎您 " + getIntent().getStringExtra("username")); }}在登录界面输入用户名之后，点击登录，通过startActivity跳转到主页面MainActivity，在MainActivity上通过getIntent()获取Intent传值。
Intent返回值给上一个Activity
另外还有这么一个场景，比如饿了么APP用户在首页选择用户所在城市，比如选择广州之后返回，首页显示广州了。这个场景就是典型Intent返回值给上一个Activity。下面我们开始编写代码：
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public class ChooseActivity extends AppCompatActivity { private TextView tvCity; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_choose); tvCity = findViewById(R.id.tv_city); tvCity.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { startActivityForResult(new Intent(ChooseActivity.this, CityListViewActivity.class), 101); } }); } @Override protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) { super.onActivityResult(requestCode, resultCode, data); if (requestCode == 101 && resultCode == RESULT_OK && data != null) { tvCity.setText(data.getStringExtra("city")); } }}1
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public class CityListViewActivity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_city); ListView listView = findViewById(R.id.listview); String[] data = {"北京", "上海", "广东", "江西", "福建", "江苏", "山东", "浙江", "四川", "云南", "贵州", "黑龙江", "哈尔滨"}; ArrayAdapter<String> array = new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, data); listView.setAdapter(array); listView.setOnItemClickListener(new AdapterView.OnItemClickListener() { @Override public void onItemClick(AdapterView<?> parent, View view, int position, long id) { Intent intent = new Intent(); intent.putExtra("city", data[position]); setResult(RESULT_OK, intent); finish(); } }); }}源码链接：https://yunjunet.cn/876800.html
