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My app crashed for unknown reason when I tried to setOnClickListener for a button in ListView

I'm building a Contact app using ListView. My ListView has 2 button. In this app, to test the respond ability of the buttons, I intended to set the button "Edit" so that when I click on it, it will change to "Clicked", and the button "Delete" will change to "Clicked", too. When I ran the Debug, the app stopped working and I couldn't get it work again (before I added the onClickListener, this app had worked property).
I don't know what is the error, and have tried many ways to fix.
Here is my row_listview.xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent" android:layout_margin="10dp">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:weightSum="5">
<ImageView
android:id="#+id/imgAvatar"
android:layout_width="0dp"
android:layout_height="70dp"
android:layout_weight="1"
android:src="#drawable/if_male3_403019" />
<LinearLayout
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="2.7"
android:orientation="vertical"
android:weightSum="2">
<TextView
android:id="#+id/tvName"
android:layout_width="wrap_content"
android:layout_height="0dp"
android:layout_weight="1"
android:paddingLeft="15dp"
android:text="Akai Shuichi"
android:textSize="16dp"
android:textColor="#000"
android:gravity="center_vertical"
/>
<TextView
android:id="#+id/tvNumber"
android:layout_width="wrap_content"
android:layout_height="0dp"
android:layout_weight="1"
android:paddingLeft="15dp"
android:text="0982xxxxxx"
android:textSize="16dp"
android:textColor="#000"
android:gravity="center_vertical"
/>
</LinearLayout>
<LinearLayout
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1.3"
android:weightSum="2"
android:orientation="vertical">
<Button
android:id="#+id/btnEdit"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
android:backgroundTint="#3FE0FF"
android:onClick="myClickHandler"
android:text="Edit"
android:textColor="#fff"
android:textStyle="bold" />
<Button
android:id="#+id/btnDelete"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
android:backgroundTint="#F73131"
android:onClick="myClickHandler"
android:text="Delete"
android:textColor="#fff"
android:textStyle="bold" />
</LinearLayout>
</LinearLayout>
And here is my MainActivity.java:
package com.huy9515gmail.mycontact;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.Toast;
import java.util.ArrayList;
import butterknife.BindView;
import butterknife.ButterKnife;
public class MainActivity extends AppCompatActivity {
#BindView(R.id.edt_inputName) EditText edtName;
#BindView(R.id.btnAdd) Button btnAdd;
#BindView(R.id.btnEdit) Button btnEdit;
#BindView(R.id.btnDelete) Button btnDelete;
#BindView(R.id.edt_inputNumber) EditText edtNumber;
#BindView(R.id.rdbtn_male) RadioButton rdbtn_male;
#BindView(R.id.rdbtn_female) RadioButton rdbtn_female;
#BindView(R.id.rdbtn_others) RadioButton rdbtn_others;
#BindView(R.id.gender) RadioGroup genderSelection;
private ListView lvContact;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ButterKnife.bind(this);
lvContact = (ListView) findViewById(R.id.lv_contact);
final ArrayList<Contact> arrContact = new ArrayList<>();
btnAdd.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
//validating contact info
if (((edtName.getText().toString().trim()) == "") || (edtNumber.getText().toString().trim() == "") || ((rdbtn_male.isChecked()==false) && (rdbtn_female.isChecked()==false) &&(rdbtn_others.isChecked()==false))) {
Toast.makeText(MainActivity.this, "Invalid contact info! Please try again!", Toast.LENGTH_SHORT).show();
}
//adding contact info
else {
Contact contact = new Contact(Gender.male, "", "");
//adding info
contact.setName(edtName.getText().toString());
contact.setNumber(edtNumber.getText().toString());
arrContact.add(contact);
}
CustomAdapter customAdapter = new CustomAdapter(MainActivity.this, R.layout.row_listview, arrContact);
lvContact.setAdapter(customAdapter);
}
});
}
public void myClickHandler(View v) {
LinearLayout vwParentRow = (LinearLayout) v.getParent();
Button btnEdit = (Button) vwParentRow.getChildAt(0);
Button btnDelete = (Button) vwParentRow.getChildAt(1);
btnEdit.setText("Clicked");
btnDelete.setText("Clicked");
}
}
And here is the row_listview.xml layout:

Instead of setting the android:onClick in XML, do the same as you did for btnAdd.
Find the view by id or use butterknife, then put the following in onCreate()
btnEdit.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// Your code here
}
});
btnDelete.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// Your code here
}
});

Make sure you have an element in your XML file with the id like this:
android:id="#+id/btnAdd"

Fragments and Layouts

When trying to run our app, we consistently have errors with conflicting fragments not letting us run the activity. Here's a screencast of the problem I am facing
As you can see, the app itself contains a multitude of problems, but my primary focus is getting the clicker to respond on the click. Here is the class page for the clicker activity:
package com.example.android.Chapsnat;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
public class ContactsFragment extends AppCompatActivity {
Button btnClick;
Button btnReset;
TextView txtCount;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.fragment_contacts);
btnClick = (Button)findViewById(R.id.buttonClick);
btnReset = (Button)findViewById(R.id.buttonReset);
txtCount = (TextView)findViewById(R.id.textViewCount);
btnClick.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
String countValue = txtCount.getText().toString();
int intCountValue = Integer.parseInt(countValue);
intCountValue++;
txtCount.setText(String.valueOf(intCountValue));
} });
btnReset.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
txtCount.setText(String.valueOf(0));
}
});
}
}
And this is the xml page it is being built in, which is also a fragment:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/fragment_contacts"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context="com.example.android.Chapsnat.ContactsFragment">
<TextView
android:id="#+id/textViewCount"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="66dp"
android:text="0"
android:textColor="#android:color/holo_purple"
android:textSize="40sp" />
<Button
android:text="Click"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/buttonClick"
android:layout_below="#+id/textViewCount"
android:layout_centerHorizontal="true"
android:layout_marginTop="79dp" />
<Button
android:text="Reset"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="171dp"
android:id="#+id/buttonReset"
android:layout_below="#+id/textViewCount"
android:layout_alignStart="#+id/buttonClick" />
</RelativeLayout>
Is there any way you can help? If so please let me know.

How to connect xml with a class on android

I have created a new .xml file named "new_game.xml" and a class named "New_Game.java"
These are not Main activity
new_game.xml:
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
<Button android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Click"
android:id="#+id/button"
android:layout_marginTop="27dp"
android:layout_alignRight="#+id/editText"/>
<EditText android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:inputType="textPersonName"
android:ems="10"
android:id="#+id/editText"
android:layout_marginTop="16dp"
android:layout_below="#+id/button"
android:layout_marginLeft="11dp"/>
<ImageView android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/imageView"
android:paddingTop="50dp"
android:paddingBottom="50dp"
android:paddingLeft="50dp"
android:paddingRight="50dp"
android:background="#drawable/ic_launcher"
android:layout_centerVertical="true"
android:layout_toLeftOf="#+id/button"/>
</RelativeLayout>
New_Game.java:
package com.example.logosquiz;
import android.app.Activity;
import android.app.ListActivity;
import android.app.TabActivity;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.RelativeLayout;
public class New_Game extends Activity {
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.new_game);
Button button1 = (Button)findViewById(R.id.button);
final EditText editText1 = (EditText)findViewById(R.id.editText);
ImageView imageView1 = (ImageView)findViewById(R.id.imageView);
button1.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
editText1.setText("Hello Android");
}
});
}
Please explain it very well
I put on AndroidManifest.xml this
<activity android:name=".New_Game"> /activity>
and this on the event onClick
Intent myIntent = new Intent(v.getContext(), New_Game.class);
startActivityForResult(myIntent, 0);

Your XML is wrong. Remove the last / from the first RelativeLayout in your XML.
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">
instead of
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
Although Eclipse should have warned you about this.

your code is correct but
button android:layout_marginTop="27dp"
edittext android:layout_marginTop="16dp"
edit text is placed on the button so when you click you are clicking on edittext not button change edittext marginTop to 30dp and check
public class New_Game extends Activity {
EditText editText1;
#override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.new_game);
Button button1 = (Button)findViewById(R.id.button);
editText1 = (EditText)findViewById(R.id.editText);
ImageView imageView1 = (ImageView)findViewById(R.id.imageView);
button1.setOnClickListener(new View.OnClickListener(){
public void onClick(View v){
editText1.setText("Hello Android");
}
});
}

creating a simple layout on android

I'm very new with android development. I'm trying to develop an application, I decided to try out the code below but I keep getting errors when I try to open it on the emulator. please can anyone tell me what I'm doing wrong?
package hajara.android.MyRecipes;
import android.app.Activity;
import android.os.Bundle;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class MyRecipesActivity extends Activity {
Button btn;
TextView t1, t2;
EditText e;
#Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
setContentView(R.layout.main);
t1 = (TextView)findViewById(R.id.text1);
t2 = (TextView)findViewById(R.id.text2);
e = (EditText)findViewById(R.id.edit1);
btn=(Button)findViewById(R.id.button1);
btn.setOnClickListener((OnClickListener) this);
}
}
My main.xml file is
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<TextView
android:id="#+id/text1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Enter a string:"
/>
<EditText android:id="#+id/edit1"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:cursorVisible="true"
android:editable="true"
android:singleLine="true"
/>
<Button android:id="#+id/button1"
android:text="OK"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
<TextView
android:id="#+id/text2"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text=""
/>
</LinearLayout>

Your onClick listener is done incorrectly. I find it easier to simply create a method such as:
public void buttonOnClick(View v) {
// Do something
}
and within your XML layout file (ie. main.xml) invoke the onClick attribute:
<Button
...
android:onClick="buttonOnClick"
...
/>

I think you haven't Declared button Properly.
btn.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// Your Code Goes here
}
});
And Hope you have Declared your Activity in Manifest File.

How to work the viewflipper?

As my below codes shows that once button five and six shows with the titlesfourq1.
I click buttonfive it will show numten then if I click numten it will show numsix. But how do I show numsix with numten in the same layout?
<?xml version="1.0" encoding="utf-8"?>
<AbsoluteLayout android:id="#+id/LinearLayout01"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical">
<AbsoluteLayout android:id="#+id/radioGroup1"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<Button android:background="#drawable/buttonsix" android:id="#+id/radio0"
android:layout_width="40dip" android:layout_height="40dip" android:layout_marginTop="50dip" android:layout_x="20dip" android:layout_y="55dip">
</Button>
<Button android:background="#drawable/buttonfive" android:id="#+id/radio1"
android:layout_width="40dip" android:layout_height="40dip" android:layout_marginTop="150dip" android:layout_x="200dip" android:layout_y="200dip">
</Button>
</AbsoluteLayout>
<ViewFlipper android:id="#+id/ViewFlipper01"
android:layout_width="wrap_content"
android:layout_height="wrap_content" android:layout_x="20dip">
<!--adding views to ViewFlipper-->
<TextView
android:id="#+id/title"
android:textStyle="bold"
android:textColor="#ffffff"
android:gravity="center_vertical|center_horizontal"
android:text="#string/titlesfourq1" android:layout_height="wrap_content" android:layout_y="10dip" android:layout_x="5dip" android:textSize="20dip" android:layout_width="340dp"/>
<Button android:text="#string/numten" android:id="#+id/number" android:textStyle="bold" android:background="#color/translucent_black" android:textColor="#ffffff"
android:layout_width="40dip" android:layout_height="40dip" android:layout_marginTop="150dip" android:layout_x="200dip" android:layout_y="200dip">
</Button>
<Button android:text="#string/numsix" android:id="#+id/number" android:textStyle="bold" android:background="#color/translucent_black" android:textColor="#ffffff"
android:layout_width="40dip" android:layout_height="40dip" android:layout_marginTop="150dip" android:layout_x="200dip" android:layout_y="200dip">
</Button>
<TextView android:id="#+id/TextView02"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Second view is now displayed"></TextView>
<TextView android:id="#+id/TextView03"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Third view is now displayed"></TextView>
</ViewFlipper>
</AbsoluteLayout>
Java:
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.widget.ViewFlipper;
public class Sfourq1 extends Activity {
Button RB0;
Button RB1;
Button RB2;
ViewFlipper VF;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.sfourq1);
/*
* Find the views declared in main.xml.
*/
RB0 = (Button) findViewById(R.id.radio0);
RB1 = (Button) findViewById(R.id.radio1);
RB2 = (Button) findViewById(R.id.number);
VF = (ViewFlipper) findViewById(R.id.ViewFlipper01);
/*
* Set a listener that will listen for clicks on the radio buttons and
* perform suitable actions.
*/
RB0.setOnClickListener(button_one);
RB1.setOnClickListener(button_two);
RB2.setOnClickListener(button_test);
}
/*
* Define a OnClickListener that will change which view that is displayed by
* the ViewFlipper
*/
private OnClickListener button_one = new OnClickListener() {
public void onClick(View v) {
switch (v.getId()) {
case R.id.radio0:
VF.setDisplayedChild(0);
Button button = (Button) v;
button.setVisibility(View.INVISIBLE);
break;
}
}
};
private OnClickListener button_two = new OnClickListener() {
public void onClick(View v) {
switch (v.getId()) {
case R.id.radio1:
VF.setDisplayedChild(1);
Button button = (Button) v;
button.setVisibility(View.INVISIBLE);
break;
}
}
};
private OnClickListener button_test = new OnClickListener() {
public void onClick(View v) {
switch (v.getId()) {
case R.id.number:
VF.setDisplayedChild(2);
Button button = (Button) v;
button.setVisibility(View.INVISIBLE);
Intent StartGameIntent = new Intent(Sfourq1.this,Home.class);
startActivity(StartGameIntent);
break;
}
}
};
}

for this you can give same tag to both buttons in different layout and whenever flip moves(can get by touch event)change focus to button with same tag.
thanx