My android small white, recently encountered in the learning process two very strange questions,
The first question, I added a SecondActivity outside the main activities, and added a few buttons, inside XML code:

 & lt; The Button 
The android: id="@ + id/button_good" 
Android: layout_width="0 dp" 
Android: layout_height="0 dp" 
Android: layout_marginTop="68 dp" 
Android: layout_marginBottom="35 dp" 
Android: text="this?" 
App: layout_constraintBottom_toTopOf="@ + id/textView" 
App: layout_constraintEnd_toEndOf="@ + id/textView2" 
App: layout_constraintStart_toStartOf="@ + id/button4" 
App: layout_constraintTop_toTopOf="parent"/& gt; 

The android: id="@ + id/button_he" 
Android: layout_width="0 dp" 
Android: layout_height="0 dp" 
Android: layout_marginEnd="133 dp" 
Android: layout_marginRight="133 dp" 
Android: layout_marginBottom="32 dp" 
Android: text="dormitory to: 
"App: layout_constraintBottom_toTopOf="@ + id/textView2" 
App: layout_constraintEnd_toEndOf="parent" 
App: layout_constraintStart_toEndOf="@ + id/baidu" 
App: layout_constraintTop_toBottomOf="@ + id/textView"/& gt; 

The android: id="@ + id/button4" 
Android: layout_width="wrap_content" 
Android: layout_height="wrap_content" 
Android: layout_marginStart="9 dp" 
Android: layout_marginLeft="9 dp" 
Android: layout_marginBottom="34 dp" 
Android: text="exit" 
App: layout_constraintBottom_toTopOf="@ + id/textView3" 
App: layout_constraintStart_toStartOf="@ + id/textView3" 
App: layout_constraintTop_toBottomOf="@ + id/textView2"/& gt; 

And, the click event is added in the activity, the Java code:

 
The Button b1=(Button) the findViewById (R.i db utton_good), b2=(Button) the findViewById (R.i db utton_he); 
The Button b4=(Button) the findViewById (R.i db utton4); 
B1. SetOnClickListener (new View. An OnClickListener () {
@ Override 
Public void onClick (View v) {
Toast. MakeText (SecondActivity. This, "this is not good," Toast. LENGTH_SHORT); 
} 
}); 

B2. SetOnClickListener (new View. An OnClickListener () {
@ Override 
Public void onClick (View v) {
Toast. MakeText (SecondActivity. This reconciliation! "" And Toast. LENGTH_LONG); 
} 
}); 

B4. SetOnClickListener (new View. An OnClickListener () {
@ Override 
Public void onClick (View v) {
Toast. MakeText (SecondActivity. This, "thank you my friends," Toast. LENGTH_SHORT); 
finish(); 
} 
}); 

I jump from the main activities in the past, click on the button, all did not Toast display text,
And the same, I in the MainActivity Settings button corresponding response events also use the Toast of display text, can be normal, according to the following:

 Button b1=(Button) the findViewById (R.i db utton1); 
The Button b2=(Button) the findViewById (R.i db utton2); 

B1. SetOnClickListener (new View. An OnClickListener () {
@ Override 
Public void onClick (View v) {
Toast. MakeText (MainActivity. This, "I am button 1, what are you doing me, button for 2 ah", 
Toast. LENGTH_SHORT). The show (); 
} 
}); 

B2. SetOnClickListener (new View. An OnClickListener () {
@ Override 
Public void onClick (View v) {
Toast. MakeText (MainActivity. This, "I am the button 2, what are you doing me, some button 1", 
Toast. LENGTH_SHORT). The show (); 
} 
}); 

Could you tell me why the second activity after the button click Toast without work?

The second question:
It worked this is happening today (yesterday), I was of the jump button to set the click event is this:

 Button b4=(Button) the findViewById (R.i db utton_tiao); 
B4. SetOnClickListener (new View. An OnClickListener () {
@ Override 
Public void onClick (View v) {
Intent temperament=new Intent (MainActivity. This, SecondActivity. Class); 
/* 
Note Intent here, not to use. This activity class instead. 
*/
StartActivity (temperament); 
} 
}); 

But today, I added a string of jump button:

 Button send_data=https://bbs.csdn.net/topics/(Button) the findViewById (R.i db utton_send_data); 
Send_data. SetOnClickListener (new View. An OnClickListener () {
@ Override 
Public void onClick (View v) {
SecondActivity String data="https://bbs.csdn.net/topics/Hello"; 
Intent temp=new Intent (MainActivity. This, SecondActivity. Class); 
Temp. PutExtra (" extra_data ", data); 
//to the intention of string message 
StartActivity (temp); 
} 
}); 

Click on the button, the original is not jump to SecondActivity, after but card program, the App directly to quit, I thought I'm every whole finish,

And, what is more fantastic, I took the string jump after the delete button on the events of the original button clicks or card program, the effect of normal jump to click on the button (send_data that can SecondActivity)
What is this why?
What's the modification method? More want to know why ()

CodePudding user response:

Behind the first problem to solve, I didn't add the show, thank you

The second problem is temporarily not solve

CodePudding user response:

Card program? Flash back, so log?