Hi I am developing an Android app using an EditText, and a add en minus button to control it's value.
I got it working now, but I wanna repeat it to multiple values. I know I can just repeat the code with different variables but the code would big really large.
Anyone an idea how to repeat the same code for multiple values?
This is my current code:
package com.lars.MyApp;
import com.lars.MyApp.R;
import android.app.Activity;
import android.os.Bundle;
import android.widget.Button;
import android.widget.EditText;
import android.view.View;
import android.view.View.OnClickListener;
public class MyAppActivity extends Activity {
int currentValue = 0;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
final EditText Value = (EditText) findViewById(R.id.Value);
Button addButton = (Button) findViewById(R.id.addButton);
Button minusButton = (Button) findViewById(R.id.minusButton);
addButton.setOnClickListener(new OnClickListener(){
public void onClick(View v) {
addValue();
Value.setText("" + currentValue);
}
});
minusButton.setOnClickListener(new OnClickListener(){
public void onClick(View v) {
minusValue();
Value.setText("" + currentValue);
}
});
}
public void addValue(){
if(currentValue <= 999){
currentValue = currentValue + 1;
}
}
public void minusValue(){
if(currentValue >= 1){
currentValue = currentValue - 1;
}
}
}
You should refactor your OnClickListeners so that they are generic. Probably the easiest way to do this is to change your addValue() method to be addValue(View v), and minusValue() to minusValue(View v). Then, in the layout xml, you add a property android:onClick=addValue or android:onClick=minusValue. You'll have to update the method bodies so that they check the view's id and do the right thing based on that, but you won't have to create and set a whole bunch of OnClickListeners in the onCreate method - you'll get that for free.
Related
I'm just a beginner in coding using Android studio and I have a couple of questions in coding a calculator (The calculator is used to only compute carbon emissions so it varies a little bit compared to an actual calculator):
How do I have a clear all button?
How do I add all of the
products that the user has calculated and show its sum? (Kind of like
how those tracking expenses kind of app)
This is my code so far:
package com.carschoolingpromo.scires.carschooling;
import android.content.Intent;
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.TextView;
public class Calculator extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_calculator);
Button caremissionscheck = findViewById(R.id.checkcar);
caremissionscheck.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent tocarbonemissions = new Intent(Calculator.this, CarbonEmissions.class);
startActivity(tocarbonemissions);
}
});
Button distancecheck = findViewById(R.id.checkdestination);
distancecheck.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent checkdistance = new Intent(Calculator.this, DistancesList.class);
startActivity(checkdistance);
}
});
final Button multiply =(Button)findViewById(R.id.multiply);
final EditText num1 =(EditText)findViewById(R.id.carboninput);
final EditText num2 =(EditText)findViewById(R.id.distanceinput);
final TextView ans =(TextView)findViewById(R.id.answer);
final TextView carbontotal=(TextView)findViewById(R.id.sumofcarbon);
multiply.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
double n1 = Double.parseDouble(num1.getText().toString());
double n2 = Double.parseDouble(num2.getText().toString());
ans.setText(String.valueOf(n1*n2));
}
});
}
}
How do I have a clear all button?
You need to create a new button in the layout file, and get a reference of it in your code, then set a click listener on that reference. Then in the onClick() implementation you will clear your 2 edit texts and 2 text views, something like this:
final Button clearAll =(Button)findViewById(R.id.clear_all);
clearAll.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
num1.setText("");
num2.setText("");
ans.setText("");
carbontotal.setText("");
}
});
How do I add all of the products that the user has calculated and show its sum? (Kind of like how those tracking expenses kind of app)
For this you need to use some sort of a way to show a list on your UI, I suggest you look into this tutorial by google to creating lists
I have 2 buttons for increasing and decreasing TextView font size:
btnZoomin.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
txtview.setTextSize(txtview.getTextSize()+1);
}
});
btnZoomout.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
txtview.setTextSize(txtview.getTextSize()-1);
}
});
But are experiencing difficulty, as it will not work.
If anyone is still facing the text size issue. You can use this code:
To increase size: tvText.setTextSize(0, tvText.getTextSize() + 2.0f);
To decrease size tvText.setTextSize(0, tvText.getTextSize() - 2.0f);
txtview.setTextSize(TypedValue.COMPLEX_UNIT_PX,txtview.getTextSize()-1);
txtview.setTextSize(TypedValue.COMPLEX_UNIT_PX,txtview.getTextSize()+1);
How can you see in the DOCS setTextSize needs 2 arguments: the TypedValue and the new size.
Your code is fine, you just have to add the TypedValue :
txtview.setTextSize(TypedValue.COMPLEX_UNIT_SP,txtview.getTextSize()-1);
txtview.setTextSize(TypedValue.COMPLEX_UNIT_SP,txtview.getTextSize()+1);
Use this text.setTextSize(TypedValue.COMPLEX_UNIT_SP,14);
Sorry for the previous code, that was wrong but i think this will work for you,
package com.example.sample;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends Activity {
int counter = 0;
private int size;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final TextView txt = (TextView) findViewById(R.id.txt);
Button btn = (Button) findViewById(R.id.button1);
counter = (int) txt.getTextSize();
btn.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
Toast.makeText(getApplicationContext(), txt.getTextSize() + "",
Toast.LENGTH_LONG).show();
size = counter++;
txt.setTextSize(size);
}
});
}
}
I am new to Android and Java and don't know why the Text value is null after I assign Text to it? This is a project for University They didn't teach us Java only gave us Eclipse and Android Sdk and Java need some help please!
package com.example.glossaryapp;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
public class Syntax extends Activity {
static String Text;
public static TextItem[] Syntax = new TextItem[50];
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.syntax);
final TextView show = (TextView) Syntax.this
.findViewById(R.id.textViewSyn);
// Linking the text View widget
int Count1 = 0;
// Using the TextView's shows method set text to display the appropriate
// arrays and indexes
if (Syntax[0] != null) {
Text = Syntax[0].displayText();
show.setText(Text);
}
// The Add button for if a user wants to add a new TextItem to the Array
Button but1 = (Button) findViewById(R.id.butAddSyntax);
but1.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
Create.strSender = "Syntax1";
startActivity(new Intent(Syntax.this, Create.class));
}// end of on click
});// butAddSyntax
// Home Button
Button but2 = (Button) findViewById(R.id.buttHomeSyntax);
but2.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
finish();
}// end of on click
});// buttonHomeSyntax
}
public void onResume() {
super.onResume();
TextView show = (TextView) Syntax.this.findViewById(R.id.textViewSyn);
if (Syntax[0] != null) {
Text = Syntax[0].displayText().toString();
show.setText(Text);
}
}
}
Using Android's LogCat will help you to solve this kind of problems.
Here you have a nice article:
http://www.vogella.com/tutorials/AndroidLogging/article.html
I think the problem is in here:
if( Syntax[0] != null ){
Text = Syntax[0].displayText();
show.setText(Text);
}
you could begin using LogCat trying this:
if( Syntax[0] != null ){
Log.d("MyApp", "Sintax (0) = " + Syntax[0].displayText());
Text = Syntax[0].displayText();
show.setText(Text);
} else Log.d("MyApp", "Nothing ");
And watch the result in the Logcat pane.
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Closed 11 years ago.
This is the .java file for a small application I am writing in Android through Eclipse, and I am having a minor error or syntax glitch.
at the end bracket marked by asterisks, eclipse is reporting the error 'Syntax error, insert ";" to complete Statement'. I have searched the code, and find nothing unaccounted for or out of place. Could someone please identify or tell me how to fix this? If you need other files, tell me in the comments. Thanks in advance :)!
package org.example.knittingframe;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.text.Editable;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class KnittingFrame extends Activity {
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
final TextView textview = (TextView)findViewById(R.id.textview);
final EditText op1 = (EditText)findViewById(R.id.NumBox1);
final EditText op2 = (EditText)findViewById(R.id.NumBox2);
final Button btnAdd = (Button)findViewById(R.id.addBox);
btnAdd.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
int a, b;
a = Integer.parseInt(op1.getText().toString());
b = Integer.parseInt(op2.getText().toString());
int sum = a + b;
textview.setText(String.valueOf(sum));
}
**}** // Here is where the error occurs
}
}
The compiler is right. You need to replace
**}** // Here is where the error occurs
with
});
to finish the btnAdd.setOnClickListener method call.
This is a statement in the onCreate(xx) and its an anonymous class, because an anonymous class is a statement you MUST terminate the statement:
btnAdd.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
int a, b;
a = Integer.parseInt(op1.getText().toString());
b = Integer.parseInt(op2.getText().toString());
int sum = a + b;
textview.setText(String.valueOf(sum));
}
**}** // Here is where the error occurs
TO:
btnAdd.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
int a, b;
a = Integer.parseInt(op1.getText().toString());
b = Integer.parseInt(op2.getText().toString());
int sum = a + b;
textview.setText(String.valueOf(sum));
}
});
Since you are using an annonymous inner class, you need to end the setOnClickListener method call with ");" as follows:
public class KnittingFrame extends Activity {
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
final TextView textview = (TextView)findViewById(R.id.textview);
final EditText op1 = (EditText)findViewById(R.id.NumBox1);
final EditText op2 = (EditText)findViewById(R.id.NumBox2);
final Button btnAdd = (Button)findViewById(R.id.addBox);
btnAdd.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
int a, b;
a = Integer.parseInt(op1.getText().toString());
b = Integer.parseInt(op2.getText().toString());
int sum = a + b;
textview.setText(String.valueOf(sum));
}
});
}
}
You started a function call: setOnClickListener(). You need to finish it. Like so:
btnAdd.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
int a, b;
a = Integer.parseInt(op1.getText().toString());
b = Integer.parseInt(op2.getText().toString());
int sum = a + b;
textview.setText(String.valueOf(sum));
}
});
If you indented properly, maybe you'd see it, but you're missing an extra parenthesis and semicolon:
package org.example.knittingframe;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.text.Editable;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class KnittingFrame extends Activity {
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
final TextView textview = (TextView)findViewById(R.id.textview);
final EditText op1 = (EditText)findViewById(R.id.NumBox1);
final EditText op2 = (EditText)findViewById(R.id.NumBox2);
final Button btnAdd = (Button)findViewById(R.id.addBox);
btnAdd.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
int a, b;
a = Integer.parseInt(op1.getText().toString());
b = Integer.parseInt(op2.getText().toString());
int sum = a + b;
textview.setText(String.valueOf(sum));
}
});
}
}
I want to make a simple calculator My code is below:
package som.dev.android.calc;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
public class CalcApp extends Activity {
/** Called when the activity is first created. */
Button addValues, subValues, equalsValue;
EditText inputValue;
int inputNum = 0;
public int value1;
public int value2;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// initializing Views
inputValue = (EditText) findViewById(R.id.editText1);
addValues = (Button) findViewById(R.id.addBtn);
subValues = (Button) findViewById(R.id.subBtn);
equalsValue = (Button) findViewById(R.id.equalsBtn);
// adding onClick Listeners
addValues.setOnClickListener(new View.OnClickListener() {
public void onClick(View arg0) {
// TODO Auto-generated method stub
pressed = true;
value1 = Integer.parseInt(inputValue.getText().toString());
inputValue.setText("");
}
});
equalsValue.setOnClickListener(new View.OnClickListener() {
public void onClick(View arg0) {
// TODO Auto-generated method stub
value2 = Integer.parseInt(inputValue.getText().toString());
int result = value1+value2;
inputValue.setText(result);// There an exception occurs....
}
});
}
}
But it does not sets result to Edittext in my app and an exception occurs and message comes Unfortunately app is colsed some thing like that so please any one tell me the solution of this problem
use this inputValue.setText(""+result);instead of inputValue.setText(result);// There an exception occurs....
just conversion integer into string
The reason you get an exception is that the EditText thinks you are setting a resource id. You need to convert the integer to a string yourself Integer.toString(result) before using it in the EditText Object. http://developer.android.com/reference/android/widget/TextView.html
change Following Line:-
inputValue.setText(result);
to
inputValue.setText(String.Valueof(result));
then your error is solved.