Android開(kāi)發(fā)學(xué)習(xí)教程（22）- Intent傳值與startActivityForResult返回值
2023-01-28 14:55 作者:ChatGPT云炬學(xué)長(zhǎng) | 我要投稿
—— 你要悄悄拔尖，然后一鳴驚人。
上一篇我們講了Intent的基本概念，現(xiàn)在我們通過(guò)一個(gè)實(shí)例來(lái)驗(yàn)證。
Intent傳值
有這么一個(gè)場(chǎng)景，用戶在登錄頁(yè)面輸入用戶名之后點(diǎn)擊登錄，跳轉(zhuǎn)到另一個(gè)頁(yè)面顯示用戶名名稱。這個(gè)場(chǎng)景就是典型的Activity間Intent傳值。下面我們開(kāi)始編寫代碼：
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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("歡迎您 "?+ getIntent().getStringExtra("username"));????}}在登錄界面輸入用戶名之后，點(diǎn)擊登錄，通過(guò)startActivity跳轉(zhuǎn)到主頁(yè)面MainActivity，在MainActivity上通過(guò)getIntent()獲取Intent傳值。
Intent返回值給上一個(gè)Activity
另外還有這么一個(gè)場(chǎng)景，比如餓了么APP用戶在首頁(yè)選擇用戶所在城市，比如選擇廣州之后返回，首頁(yè)顯示廣州了。這個(gè)場(chǎng)景就是典型Intent返回值給上一個(gè)Activity。下面我們開(kāi)始編寫代碼：
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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",?"廣東",?"江西",?"福建",?"江蘇",?"山東",?"浙江",?"四川",?"云南",?"貴州",?"黑龍江",?"哈爾濱"};????????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();????????????}????????});????}}源碼鏈接：https://yunjunet.cn/876800.html
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