Java MainActivity中的Android BroadcastReceiver onReceive更新文本视图
在MainActivity中,我有一个TextView:textV1。我在MainActivity中也有一个更新textview的方法:Java MainActivity中的Android BroadcastReceiver onReceive更新文本视图,java,android,user-interface,background,textview,Java,Android,User Interface,Background,Textview,在MainActivity中,我有一个TextView:textV1。我在MainActivity中也有一个更新textview的方法: public void updateTheTextView(final String t) { MainActivity.this.runOnUiThread(new Runnable() { public void run() { TextView textV1 = (TextView) findViewByI
public void updateTheTextView(final String t) {
MainActivity.this.runOnUiThread(new Runnable() {
public void run() {
TextView textV1 = (TextView) findViewById(R.id.textV1);
textV1.setText(t);
}
});
}
在BroadcasrReceiver中,我需要在MainActivity中更新textV1中的文本
public class NotifAlarm extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
// other things done here like notification
// NEED TO UPDATE TEXTV1 IN MAINACTIVITY HERE
}
}
如何做到这一点?BroadcastReceiver从服务运行。这个代码我无法更改。我可以从onReceive()访问和更改MainActivity中的textV1吗?我尝试过很多事情,但都失败了 在
MainActivity
中初始化MainActivity
类的变量,如下所示
public class MainActivity extends Activity {
private static MainActivity ins;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ins = this;
}
public static MainActivity getInstace(){
return ins;
}
public void updateTheTextView(final String t) {
MainActivity.this.runOnUiThread(new Runnable() {
public void run() {
TextView textV1 = (TextView) findViewById(R.id.textV1);
textV1.setText(t);
}
});
}
}
public class NotifAlarm extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
try {
MainActivity .getInstace().updateTheTextView("String");
} catch (Exception e) {
}
}
}
创建类的实例,然后将值传递给更改TextView值的函数请遵循以下步骤: 在BroadcastReceiver中,重写onReceive方法,并根据需要粘贴这些行或更改主题
private Handler handler = new Handler(); // Handler used to execute code on the UI thread
// Post the UI updating code to our Handler
handler.post(new Runnable() {
@Override
public void run() {
//Toast.makeText(context, "Toast from broadcast receiver", Toast.LENGTH_SHORT).show();
YourActivityToUpdate.updateTheTextView(message);
YourActivityToUpdateinst = YourActivityToUpdate.instance();
if(inst != null) { // your activity can be seen, and you can update it's context
inst.updateTheTextView(message);
}
}
});
现在我们解释一下updateTheTextView和inst
请在活动更新课中粘贴这些行
private static SignUpVerify mInst;
public static SignUpVerify instance() {
return mInst;
}
@Override
public void onStart() {
super.onStart();
mInst = this;
}
@Override
public void onStop() {
super.onStop();
mInst = null;
}
这是应该放在ActivityToUpdate类中的updateTheTextView方法
public void updateTheTextView(final String verifyCodeValue) {
Log.i("verifyCodeValue", verifyCodeValue);
YourTextViewToUpdate.setText(verifyCodeValue);
}
我认为这是一个更好的方法,多亏了“kevin lynx”如果有人在搜索这个精确的解决方案,但在Kotlin,请执行以下操作:
class MainActivity : AppCompatActivity() {
companion object {
var ins: MainActivity? = null
fun getInstance(): MainActivity? {
return ins
}
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
ins = this
}
fun updateTheTextView(t: String) {
this@MainActivity.runOnUiThread {
val textV1 = findViewById<TextView>(R.id.textV1)
textV1.text = t
}
}
}
class NotifAlarm : BroadcastReceiver() {
override fun onReceive(context: Context?, intent: Intent?) {
try {
MainActivity.getInstance()?.updateTheTextView("The String")
} catch (e: Exception) {
}
}
}
class MainActivity:AppCompatActivity(){
伴星{
变量ins:MainActivity?=null
有趣的getInstance():MainActivity{
返回
}
}
重写创建时的乐趣(savedInstanceState:Bundle?){
super.onCreate(savedInstanceState)
ins=这个
}
趣味updateTheTextView(t:String){
this@MainActivity.runOnUiThread {
val textV1=findViewById(R.id.textV1)
text v1.text=t
}
}
}
类NotifAlarm:BroadcastReceiver(){
覆盖接收(上下文:上下文?,意图:意图?){
试一试{
MainActivity.getInstance()?.updateTheTextView(“字符串”)
}捕获(e:例外){
}
}
}
#使用界面
处理这种情况的另一种方法是使用接口。我将描述这种方法的优点,但首先,让我们看看它是如何实现的
遵循以下步骤:1)创建一个接口
public interface MyBroadcastListener{
public void doSomething(String result);
}
2)在BroadCastReceiver中初始化侦听器
public class NotifAlarm extends BroadcastReceiver {
private MyBroadcastListener listener;
@Override
public void onReceive(Context context, Intent intent) {
listener = (MyBroadcastListener)context;
// other things done here like notification
// NUPDATE TEXTV1 IN MAINACTIVITY HERE
listener.doSomething("Some Result");
}
}
3)在活动中实现接口并重写方法
public YourActivity extends AppCompatActivity implements MyBroadcastListener{
// Your Activity code
public void updateTheTextView(String t) {
TextView textV1 = (TextView) findViewById(R.id.textV1);
textV1.setText(t);
}
@Override
public void doSomething(String result){
updateTheTextView(result); // Calling method from Interface
}
}
##使用界面的优点
- 当您将BroadcastReceiver放在不同的文件中时
- 解耦广播接收机
在活动中实现接口并重写方法。就这样
public ListActivity extends AppCompatActivity implements MyBroadcastListener{
// Your Activity code
public void startDetailActivity(String title) {
Intent i = new Intent(ListActivity,this, DetailActivity.class);
i.putExtra("Title", title);
startActivity(i);
}
@Override
public void doSomething(String result){
startDetailActivity(String title); // Calling method from Interface
}
}
在broadcastreceiver类中发送广播
public class mybroadcaster extends BroadcastReceiver{
@Override
public void onReceive(Context context, Intent intent) {
context.sendBroadcast(new Intent("updatetext"));
}
}
在您的活动中,注册广播接收器并调用它,在onReceive
上执行您的工作,然后在onDestroy()中注销广播接收器
只需获取一个静态字符串,然后将此textview的结果存储在其中,并在此类中访问它。感谢您的回复。对不起,我不知道你的意思。你能解释一下吗?非常感谢您的帮助。在MainActivity中声明一个静态字符串变量,然后将textview的值存储在该字符串中,然后您可以在任何类中的任何位置使用该字符串。我认为您可以这样做,但我不确定,请试一试。谢谢,我可以使用静态字符串,这不会更改mainactivity中textview中的文本。我需要能够更改onreceive()的文本形式。GetInstance()在broadcastreceiver:MainActivity.GetInstance()中不起作用。updateTheTextView(“字符串”);不知道getinstancejust在MainActivity中创建了这个方法,我也更新了答案。你,InnocentKiller和ashish,太棒了!工作完美。非常感谢。将答案标记为“求解”,以便帮助其他人找到答案。private static main代码>导致活动泄漏的可怕想法在updateTheTextView函数中不起作用:java.lang.NullPointerException:尝试在空对象引用上调用虚拟方法“android.view.Window$Callback android.view.Window.getCallback()”-这是我一直面临的问题。
public class MyActivity extends Activity{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
registerReceiver(broadcastReceiver, new IntentFilter("updatetext"));
}
BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
// do your work here
}
};
@Override
protected void onDestroy() {
super.onDestroy();
unregisterReceiver(broadcastReceiver);
}
}