Register an activity in AndroidManifast. If you want to run an Activity, you must first register
<activity
android:name=".FirstActivity"
android:label="This is my first Activity" //title bar
>
<intent-filter >
//Let FirstActivity, As main Activity
<action android:name="android.intent.action.MAIN"/>
<category android:name="android.intent.category.LAUNCHER"/>
</intent-filter>
</activity>
=== ========
Toast application
Toast.makeText(FirstActivity.this, "show Toast", Toast.LENGTH_LONG).show();
//.makeText returns the Toast object, and then calls the show method
FirstActivity.this, In which Activity is displayed
===================
Start the second Activity
and register the Activity first:
<activity
android:name=".SecondActivity" //class name
>
</activity>
//Click the button to start another Activity
class Listener2 implements
OnClickListener { @Override
public void onClick(View v ) {
//FirstActivity.this, the current Activity
//SecondActivity.class, the Activity you want to start
Intent intent = new Intent(FirstActivity.this, SecondActivity.class);
startActivity(intent);//Start Activity
}
=== ==============================================================================================================================================================================================
_
_
_ /Specify the data to be manipulated by the Intent object
//Generally transmitted through a string, parsed by Uri
intent.setData(Uri.parse("tel:10086"));
startActivity(intent);//Start Activity
===========================
Pass data to the next Activity
public void onClick(View v) {
Intent intent = new Intent(FirstActivity.this,SecondActivity.class);
String data="1234qwer";
//Pass data to the next Activity
//key, key; data, value
intent.putExtra("key", data);
startActivity(intent);
}
//Get the passed data
//Get the Intent of the current Activity
Intent intent = getIntent();
String string = intent.getStringExtra("key ");//Get the passed data
Log.d("SecondActivity", string);
Toast.makeText(SecondActivity.this, string, Toast.LENGTH_LONG).show();
===========================
Return data to the previous Activity
step1
public void onClick(View v) {
Intent intent = new Intent(FirstActivity.this , SecondActivity.class);
startActivityForResult(intent, 1);// Return data to the previous Activity
}
step2
@Override
public void onClick(View v) {
Intent intent = new Intent();
intent.putExtra("key1", " value1");
setResult(RESULT_OK, intent);//Up to an Activity, return data
finish();//Destroy Activity
}
step3
//
Override @Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
switch ( requestCode) {
case 1:
if (resultCode == RESULT_OK) {
String string = data.getStringExtra("key1");
Log.d("SecondActivity", string);
}
break;
default:
break;
}
}
========== =======================
Know which Activity is currently in
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//Get the current instance The class name
// and print it out through log
Log.d("MainActivity", getClass().getSimpleName());
}
Android.Activity
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