Develop Reference

How to switch between 2 TextViews places on the layout?

I have an OnClickListener that listens to Button A clicks. I also have 2 TextViews below the Button.
I want that on every click on Button A, the 2 TextViews will switch their places between them, like this:
Before clicking:
TextView A
TextView B
After clicking:
TextView B
TextView A
How can I do it? Is there a special function that meant to do that? or some kind of a trick? Thanks!
actvity_main.xml:
<?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:layout_width="fill_parent"
android:layout_height="fill_parent"
android:gravity="start"
tools:context="com.intap.tof.MainActivity">
<TextView
android:id="#+id/txtA"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true"
android:textAppearance="?android:attr/textAppearanceMedium"
android:textSize="20dp"
android:visibility="visible"/>
<TextView
android:id="#+id/txtB"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_alignParentLeft="true"
android:layout_below="#+id/txtA
android:layout_marginTop="83dp"
android:textAppearance="?android:attr/textAppearanceMedium"
android:visibility="visible"
android:textSize="20dp" />
</RelativeLayout>
MainActivity.java:
txtA = (TextView) findViewById(R.id.txtA);
txtB = (TextView) findViewById(R.id.txtB);
float mAX = txtA.getX();
float mAY = txtA.getY();
float mBX = txtB.getX();
float mBY= txtB.getY();
txtA.setX(mBX);
txtA.setY(mBY);
txtB.setX(mAX);
txtB.setY(mAY);

Trick is changing the x and y axis of both views :
Your xml code:
<?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:layout_width="fill_parent"
android:layout_height="fill_parent"
android:gravity="start"
tools:context="com.intap.tof.MainActivity">
<TextView
android:id="#+id/txtA"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true"
android:textAppearance="?android:attr/textAppearanceMedium"
android:textSize="20dp"
android:text="A"
android:tag="A"
android:clickable="true"
android:visibility="visible"/>
<TextView
android:id="#+id/txtB"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_alignParentLeft="true"
android:layout_below="#+id/txtA"
android:text="B"
android:tag="B"
android:clickable="true"
android:layout_marginTop="83dp"
android:textAppearance="?android:attr/textAppearanceMedium"
android:visibility="visible"
android:textSize="20dp" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="switch"
android:id="#+id/btn1"
android:onClick="onClickButton"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true" />
</RelativeLayout>
Java Code :
public class MainActivity extends Activity {
TextView txtA,txtB;
boolean _isOnTxtA;
Button btn1;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
txtA = (TextView)findViewById(R.id.txtA);
txtB = (TextView)findViewById(R.id.txtB);
btn1 = (Button)findViewById(R.id.btn1);
}
public void onClickButton(View v)
{
float mPos1x,mPos1y,mPos2x,mPos2y;
mPos1x = txtB.getX();
mPos1y = txtB.getY();
mPos2x = txtA.getX();
mPos2y= txtA.getY();
if(_isOnTxtA)
{
txtB.setX(mPos2x);
txtB.setY(mPos2y);
txtA.setX(mPos1x);
txtA.setY(mPos1y);
_isOnTxtA = false;
}
else
{
txtB.setX(mPos2x);
txtB.setY(mPos2y);
txtA.setX(mPos1x);
txtA.setY(mPos1y);
_isOnTxtA= true;
}
}
}

View.bringToFront method may be useful.
Where your layout is like:
<LinearLayout>
<TextView A>
<TextView B>
</LinearLayout>
To call bringToFront on TextView A will bring it front (the last position in the parent LinearLayout).
<LinearLayout>
<TextView B>
<TextView A>
</LinearLayout>
For more detailed example, below is layout.xml:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/text_holder"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".MainActivity">
<TextView
android:id="#+id/text_a"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/text_a" />
<TextView
android:id="#+id/text_b"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/text_b" />
</LinearLayout>
In your OnClickListener (in your Activity) call:
View textViewA = findViewById(R.id.text_a);
textViewA.bringToFront();
This should work.
Toggling behavior can be achieved by this application. For example:
ViewGroup textHolder = (ViewGroup) findViewById(R.id.text_holder);
textHolder.getChildAt(0).bringToFront();
ViewGroup.getChildAt(0) always returns the first child of the ViewGroup. So everytime you call bringToFront on the first child will be bring to front.

All previous answers do not work because you use a relative layout where a linear layout will suffice.
If you have to go RelativeLayout, do the following in your click listener
TextView textA = (TextView) findViewById(R.id.txtA);
TextView textB = (TextView) findViewById(R.id.txtB);
RelativeLayout.LayoutParams textALayoutParams = (RelativeLayout.LayoutParams) textA.getLayoutParams();
textALayoutParams.addRule(RelativeLayout.BELOW, R.id.txtB);
textA.setLayoutParams(textALayoutParams);
RelativeLayout.LayoutParams textBLayoutParams = (RelativeLayout.LayoutParams) textB.getLayoutParams();
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
textBLayoutParams.removeRule(RelativeLayout.BELOW);
} else {
textBLayoutParams.addRule(RelativeLayout.BELOW,0);
}
textB.setLayoutParams(textBLayoutParams);
This will place A under B. You can do the same for reversing.

Use buttons in game-style scenario

I have a 5 linear layouts, each containing 10 buttons, which gives rise to a 5 by 10 array of buttons. I would like the user to select 5 buttons, and each button contains a certain point value. On the next page, I would like the sum of the point values of these 5 buttons to appear in a textview.
Here is what I have tried so far, using a small sample of my code.
On the xml file: (this is a 2 by 3 sample)
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<Button
android:id="#+id/button11"
android:layout_width="0dip"
android:layout_weight="1"
android:layout_height="wrap_content"
android:text="50" />
<Button
android:id="#+id/button12"
android:layout_width="0dip"
android:layout_weight="1"
android:layout_height="wrap_content"
android:text="50" />
<Button
android:id="#+id/button13"
android:layout_width="0dip"
android:layout_weight="1"
android:layout_height="wrap_content"
android:text="75" />
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<Button
android:id="#+id/button21"
android:layout_width="0dip"
android:layout_weight="1"
android:layout_height="wrap_content"
android:text="00" />
<Button
android:id="#+id/button22"
android:layout_width="0dip"
android:layout_weight="1"
android:layout_height="wrap_content"
android:text="25" />
<Button
android:id="#+id/button23"
android:layout_width="0dip"
android:layout_weight="1"
android:layout_height="wrap_content"
android:text="75" />
</LinearLayout>
I am not sure what to do on the java file, but I was considering giving each button id a value (which is currently represented by the name of the button) and adding up all the values, which will then be displayed on the next page.

You can just convert the text on the button to an integer:
int value = 0;
try {
value = Integer.parseInt(button.getText().toString());
}
catch(NumberFormatException nfe) {
}

Say that xml file is called activity_main.xml. You need to have an Activity class, let's call it MainActivity.java
MainActivity.java
public class MainActivity extends Activity implements OnClickListener{
private totalVal = 0;
#Override
protected void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button button12 = (Button) findViewById(R.id.button12);
button12.setOnClickListener(this);
// ... Do the same for the rest of the buttons
}
#Override
public void onClick(View v){
switch(v.getId(){
case R.id.button12:
int textVal = Integer.parseInt(v.getText().toString());
totalVal = totalVal + textVal;
// do whatever else you want to when the button is clicked
break;
// ... Do the same for the rest of the buttons
}
You would also need a button that says you are done, and implement it in a similar way

how to clear entries from several EditTexts?

I am new to java and android so please forgive me if i am asking to simple question.
I have an application which requires user input in two EditTexts. Those inputs are multipied and result is displayed in TextView. I would like to use "clear entries" button which would clear the content of user entries and displayed result. Is there any way to do it?
Here is an application code.
package c.example.rectangle;
import android.os.Bundle;
import android.view.View;
import android.app.Activity;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class MainActivity extends Activity implements OnClickListener{
EditText l;
EditText w;
TextView a;
Button b;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
l = (EditText) findViewById(R.id.length);
w = (EditText) findViewById(R.id.width);
a = (TextView) findViewById(R.id.lblarea);
b = (Button) findViewById(R.id.calculate);
b.setOnClickListener(this);
}
public void onClick(View v) {
calculateRectangle(l.getText().toString(), w.getText().toString());
}
private void calculateRectangle(String clength, String cwidth){
double area = Double.parseDouble(clength)*Double.parseDouble(cwidth);
a.setText(String.valueOf(area));
}}
And here is my XML Code.
<?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:background="#8B4513"
android:orientation="vertical" >
<TextView
android:id="#+id/label1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:layout_marginTop="20dp"
android:background="#2F4F4F"
android:gravity="center"
android:text="#string/rect"
android:textAppearance="?android:attr/textAppearanceMedium" />
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#8B4513"
android:orientation="horizontal" >
<TextView
android:id="#+id/label2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="30dp"
android:layout_marginTop="50dp"
android:background="#2F4F4F"
android:gravity="center"
android:text="#string/cm"
android:textAppearance="?android:attr/textAppearanceMedium" />
<EditText
android:id="#+id/length"
android:layout_width="110dp"
android:layout_height="21dp"
android:layout_marginLeft="40dp"
android:layout_marginTop="50dp"
android:background="#2F4F4F"
android:ems="10"
android:gravity="center"
android:hint="#string/help"
android:inputType="text" />
</LinearLayout>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#8B4513"
android:orientation="horizontal" >
<TextView
android:id="#+id/label3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#2F4F4F"
android:layout_marginLeft="30dp"
android:layout_marginTop="20dp"
android:text="#string/breadth"
android:textAppearance="?android:attr/textAppearanceMedium" />
<EditText
android:id="#+id/width"
android:layout_width="110dp"
android:layout_height="21dp"
android:layout_marginLeft="33dp"
android:layout_marginTop="20dp"
android:background="#2F4F4F"
android:inputType="text"
android:hint="#string/help"
android:ems="10"
android:gravity="center"
>
<requestFocus />
</EditText>
</LinearLayout>
<Button
android:id="#+id/calculate"
android:layout_width="fill_parent"
android:layout_marginLeft="100dip"
android:layout_marginRight="100dip"
android:layout_height="wrap_content"
android:text="#string/calculate"
android:layout_marginTop="20dp" />
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#8B4513"
android:orientation="horizontal" >
<TextView
android:id="#+id/label4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="30dp"
android:layout_marginTop="20dp"
android:background="#2F4F4F"
android:text="#string/area"
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="#+id/lblarea"
android:layout_width="110dp"
android:layout_height="21dp"
android:layout_marginLeft="60dp"
android:layout_marginTop="20dp"
android:background="#2F4F4F"
android:gravity="center"/>
</LinearLayout>
<Button
android:id="#+id/clear"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="100dip"
android:layout_marginRight="100dip"
android:layout_marginTop="20dp"
android:text="#string/clear" />
</LinearLayout>
I would be very appreciate for the answer.

Why not just set both editTexts to empty when you no longer need the data in them to be displayed?
EditText.setText("");
Same thing with the TextView;
TextView.setText("");

If you are wanting to iterate through them, you can put them in a list then use a for loop to set the text to ""
List<EditText> myList = new List<EditText>();
myList.add(editText1);
Then in your clear method
for (int x = 0; x < myList.size(); x++
{
myList.get(x).setText("");
}

Why nobody seems to use the really useful android:onClick ?
<Button
...
android:text="#string/calculate"
android:onClick="calculate" />
<Button
...
android:text="#string/clear"
android:onClick="clearForm" />
With the following activity :
class MyActivity extends Activity
{
...
/**
* Calculate
* android:onClick="calculate"
*/
public void calculate(View view)
{
// Handle click on your 'Calculate' button
}
/**
* Clear form
* android:onClick="clearForm"
*/
public void clearForm(View view)
{
int[] ids = new int[]{R.id.length, R.id.width};
for(int id : ids)
{
((EditText) this.findViewById(id).)setText("");
}
}
}
This way, you do not have to care about ids and your code will be more clean than clean.
Ids should not be overused! They are great on views that can be 'changed' by the user to handle those changes (and to enjoy the onSaveInstanceState() natural behavior) but that's it!
IMO.

If you want to create a clear button, do the following.
Create a Button in your xml:
<Button
android:id="#+id/clear_button"
... you own layout prefs ...
/>
Create a listener for the button in your code:
OnClickListener clearButtonListener = new OnClickListener(){
#Override
public void onClick(View view) {
((EditText)findViewById(R.id.id_for_text_box_a)).setText("");
//...do this for all your edit texts that you want to clear
}
};
Connect the listener to the button
Button clearButton = (Button) findViewById(R.id.clear_button);
clearButton.setOnClickListener(clearButtonListener);
Alternatively, instead of finding the edit texts by id in the listener, they could be instance variables that get initialized in onCreate or wherever. I would also recommend not using one letter variable names.
Personally, I would set OnClickListeners instead of the onClick attribute in the XML. Although using the XML onClick attribute may amount to fewer lines of code, it unfortunately creates a very tight coupling of layout and functionality. I prefer to have XML for layout, and Java for functionality. Additionally, being forced to use ids amounts to requiring XML elements to have variable names, which makes for more readable layout code (what is this button? what is this checkbox for?). Another problem I see with using the onClick attribute is that it forces your methods called to be public, which doesn't really make sense for many of these methods. I prefer to understand what an Activity does functionally through reading the Java, and I would rather not have unreferenced public methods floating around in my Activities.

EditText Field Is Crashing My Android App

Hi all i have updated my post to show the full xml file, which will show if i am doing something wrong.
i implemented a custom dialog with an edit text field and it keeps crashing. I will
also like to access the values filled in the text field. Any idea where i am going wrong? Thanks.
Below is the offending/troublesome??? code
First i show the xml file which contains my layout for the alert dialog.
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content" android:layout_height="wrap_content">
<ImageView android:id="#+id/ImageView01"
android:layout_width="wrap_content" android:layout_height="wrap_content"
android:layout_centerHorizontal="true" />
<ScrollView android:id="#+id/ScrollView01"
android:layout_width="wrap_content" android:layout_below="#+id/ImageView01"
android:layout_height="200px">
<TextView android:text="#+id/TextView01" android:id="#+id/TextView01"
android:layout_width="wrap_content" android:layout_height="wrap_content" />
<EditText
android:id="#+id/lastname"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:hint="blah"
/>
</ScrollView>
<Button android:id="#+id/Button01"
android:layout_below="#id/ScrollView01"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:text="Cancel" />
</RelativeLayout>
Then main activity file which implements
my button click events...etc.
.......
setContentView(R.layout.main);
//this button will show the dialog
Button button1main = (Button) findViewById(R.id.Button01main);
button1main.setOnClickListener(new View.OnClickListener() {
public void onClick(View OnClickListener) {
//set up dialog
final Dialog dialog = new Dialog(MoredialogActivity.this);
dialog.setContentView(R.layout.maindialog);
dialog.setTitle("This is my custom dialog box");
dialog.setCancelable(true);
TextView text = (TextView) dialog.findViewById(R.id.TextView01);
text.setText(R.string.lots_of_text);
//set up image view
ImageView img = (ImageView) dialog.findViewById(R.id.ImageView01);
img.setImageResource(R.drawable.icon);
//set up button
Button button = (Button) dialog.findViewById(R.id.Button01);
button.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
dialog.dismiss();
//finish();
}
});
dialog.show();
}
});
}
}

You have two items in your ScrollView. According to the doc :
A ScrollView is a FrameLayout, meaning you should place one child in
it containing the entire contents to scroll; this child may itself be
a layout manager with a complex hierarchy of objects.
So you should had another layout, like a linear layout :
<ScrollView
android:id="#+id/ScrollView01"
android:layout_width="wrap_content"
android:layout_below="#+id/ImageView01"
android:layout_height="200px">
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:orientation="vertical"
android:gravity="center">
<TextView
android:text="#+id/TextView01"
android:id="#+id/TextView01"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<EditText
android:id="#+id/lastname"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:hint="blah" />
</LinearLayout>
</ScrollView>

negative number input(EditText) getting unsigned

i'm doing a cable length calculator, and i'm having trouble with negative numbers.
EditTexts are like this
<EditText android:layout_height="wrap_content" android:layout_weight="1" android:inputType="numberDecimal|numberSigned" android:layout_width="40px" android:id="#+id/rxmax">
</EditText>
Then i use them like this:
final EditText rxmax = (EditText) findViewById(R.id.rxmax);
double RXmax = new Double(rxmax.getText().toString());
After i do a simple calculation:
double OPBmax = TXmax - RXmax;
Somewhere the inputted negative number turns positive. i'm guessing at the toString conversation but i don't find anything on how to prevent this.

Use
android:digits="0123456789"
EX:
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:digits="0123456789"
android:gravity="center"
android:inputType="numberSigned"
android:textColor="#color/black"
android:textSize="#dimen/font_size_small" />

I've tried this, and it works...
Activity:
double RXmax;
EditText rxmax;
TextView tv;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
rxmax = (EditText) findViewById(R.id.rxmax);
tv = (TextView) findViewById(R.id.text);
}
public void click(View v) {
RXmax = new Double(rxmax.getText().toString());
tv.setText(Double.toString(RXmax));
}
main.xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="fill_parent"
android:layout_height="fill_parent">
<EditText android:layout_height="wrap_content"
android:layout_weight="1" android:inputType="numberDecimal|numberSigned"
android:layout_width="40px" android:id="#+id/rxmax">
</EditText>
<TextView android:id="#+id/text" android:layout_width="fill_parent"
android:layout_height="wrap_content" android:text="#string/hello" />
<Button android:layout_height="wrap_content" android:id="#+id/button1"
android:layout_weight="1" android:text="Button" android:layout_width="wrap_content"
android:onClick="click"></Button>
</LinearLayout>
If I type -2, after clicking the TextView displays -2.0
If you're using Eclipse, try Project --> Clean..., and select your project. Maybe this will help.