I'm new to Android. I'm developing an app which gives all the possible combination number based on the user input and separated it by comma.
For example the user input is: 1234
The output should be list all the possible number combination from "1234" like
"1234,1243,1324,1342,1423,1432,2134,etc.."
And there's also another EditText that limit the output by setting it to 1 or 2 or 3 or 4(max).
For example the user input is: 2
The output should be list all the possible number combination from "1234" by "2" digits
"12,13,14,21,23,24,31,32,34,41,42,43"
This is my MainActivity.java
package com.example.androidtest1;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.EditText;
import java.util.Random;
public class MainActivity extends AppCompatActivity {
EditText et_input1, et_output1;
Button b_generate, b_clear;
CheckBox checkBox1;
Random r;
int min,output;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
EditText mEdit = (EditText) findViewById(R.id.et_output1);
mEdit.setEnabled(false);
r = new Random();
et_input1 = (EditText) findViewById(R.id.et_input1);
et_output1 = (EditText) findViewById(R.id.et_output1);
b_generate = (Button) findViewById(R.id.b_generate);
b_clear = (Button) findViewById(R.id.b_clear);
checkBox1 = (CheckBox) findViewById(R.id.checkBox1);
b_generate.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (et_input1.length()==0){
et_input1.setError("Insert numbers");
}else if(checkBox1.isChecked()){
min = Integer.parseInt(et_input1.getText().toString());
output = (min);
et_output1.setText("" + output + "*");
et_input1.setError(null);
}
else{
et_input1.setError("Check the checkbox");
}
}
});
b_clear.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
et_output1.getText().clear();
et_input1.getText().clear();
return;
}
});
}
}
Related
MainActivity
package com.example.greetings_john_sporn;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {
EditText nameText;
TextView textView;
Button btn;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
nameText = (EditText) findViewById(R.id.nameText);
textView = (TextView) findViewById(R.id.textGreeting);
btn = (Button) findViewById(R.id.buttonSayHello);
nameText.setText("");
}
public void sayHello(View view) {
if(nameText != null) {
textView.setText("Hello " + nameText.getText());
btn.setEnabled(true);
} else {
textView.setText("You must enter a name");
btn.setEnabled(false);
}
}
}
Need help setting the text to "You must enter a name" when the nameText is null. For some reason even when the nameText field is empty it still outputs "Hello" when it should be outputting "You must enter a name".
Probably you need to check if the text of your EditText is null, not the EditText widget itself.
Try changing your condition
if(nameText != null) {
to
if (!TextUtils.isEmpty(nameText.getText())) {
I am making a calculator and I am stumped on this part. I want to have the value inputted from the user for inputG only to be between numbers 1-100. Then, grab that value and use it in a formula.
My logic is off somewhere and I need help finding what I did wrong. I am using Java, not Kotlin.
package com.example.rvbtcal;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
TextView inputMoles = (EditText) findViewById(R.id.txtMoles);
EditText inputML = (EditText) findViewById(R.id.txtmL);
EditText inputG = (EditText) findViewById(R.id.txtG);
TextView outputAnswer = (TextView) findViewById(R.id.txtAnswer);
Button btnCalculate = (Button) findViewById(R.id.btnCalculate);
Spinner spinner = (Spinner) findViewById(R.id.spnN);
ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this,
R.array.arrayN, android.R.layout.simple_spinner_item);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner.setAdapter(adapter);
double iM = Double.parseDouble(inputMoles.getText().toString());
double iML = Double.parseDouble(inputML.getText().toString());
double ioA = Double.parseDouble(inputG.getText().toString());
double textN = Double.parseDouble(spinner.getSelectedItem().toString());
if (ioA >= 0 || ioA <= 101){
Toast.makeText(MainActivity.this,"Enter a number between 1-100", Toast.LENGTH_SHORT);
}
btnCalculate.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
double Answer1 = (iM * iML * textN) / (ioA / 1000);
double FinalAnswer=(Answer1*1000000);
outputAnswer.setText(String.format("%.3f",FinalAnswer));
// String FinalAnswer2=String.valueOf(FinalAnswer);
// outputAnswer.setText(FinalAnswer2);
}
});
}
}
I now have my code like this below, however, the calculations are still made even with the If statement. I tried an else statement but then the answer is blank no matter if the numbers for input g fall within the parameters.
package com.example.rvbtcal;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
TextView inputMoles = (EditText) findViewById(R.id.txtMoles);
EditText inputML = (EditText) findViewById(R.id.txtmL);
EditText inputG = (EditText) findViewById(R.id.txtG);
TextView outputAnswer = (TextView) findViewById(R.id.txtAnswer);
Button btnCalculate = (Button) findViewById(R.id.btnCalculate);
Spinner spinner = (Spinner) findViewById(R.id.spnN);
ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this,
R.array.arrayN, android.R.layout.simple_spinner_item);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner.setAdapter(adapter);
btnCalculate.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
double iM = Double.parseDouble(inputMoles.getText().toString());
double iML = Double.parseDouble(inputML.getText().toString());
double ioA = Double.parseDouble(inputG.getText().toString());
double textN = Double.parseDouble(spinner.getSelectedItem().toString());
if (ioA < 0 || ioA > 100) {
Toast.makeText(MainActivity.this, "Enter a number between 1-100", Toast.LENGTH_SHORT);
}
double Answer1 = (iM * iML * textN) / (ioA / 1000);
double FinalAnswer = (Answer1 * 1000000);
outputAnswer.setText(String.format("%.3f", FinalAnswer));
}
});
}
}
My final code for others who may struggle with this in the future here is the finished product (for now):
package com.example.rvbtcal;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
TextView inputMoles = (EditText) findViewById(R.id.txtMoles);
EditText inputML = (EditText) findViewById(R.id.txtmL);
EditText inputG = (EditText) findViewById(R.id.txtG);
TextView outputAnswer = (TextView) findViewById(R.id.txtAnswer);
Button btnCalculate = (Button) findViewById(R.id.btnCalculate);
Spinner spinner = (Spinner) findViewById(R.id.spnN);
ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this,
R.array.arrayN, android.R.layout.simple_spinner_item);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner.setAdapter(adapter);
btnCalculate.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
double iM = Double.parseDouble(inputMoles.getText().toString());
double iML = Double.parseDouble(inputML.getText().toString());
double ioA = Double.parseDouble(inputG.getText().toString());
double textN = Double.parseDouble(spinner.getSelectedItem().toString());
if (ioA <= 0 || ioA > 100) {
Toast.makeText(MainActivity.this, "Enter a number between 1-100", Toast.LENGTH_LONG).show();
outputAnswer.setText("");
return;
}
double Answer1 = (iM * iML * textN) / (ioA / 1000);
double FinalAnswer = (Answer1 * 1000000);
outputAnswer.setText(String.format("%.3f",FinalAnswer));
}
});
}
}
You need to move the following lines into the btnCalculate.setOnClickListener,
double iM = Double.parseDouble(inputMoles.getText().toString());
double iML = Double.parseDouble(inputML.getText().toString());
double ioA = Double.parseDouble(inputG.getText().toString());
double textN = Double.parseDouble(spinner.getSelectedItem().toString());
if (ioA < 1 || ioA > 100) {
Toast.makeText(MainActivity.this,"Enter a number between 1-100", Toast.LENGTH_SHORT).show();
return;
}
You need to get the user input after the user taps on the btnCalculate because that's where you can get the latest input of the user.
What you are doing is fetching the value as soon as the EditText view is being created. Hence it returns an empty string. And when you try to pass an empty string to double it should give you an Exception. Unless you have assigned a text value to the EditText in your XML.
this code work very well but now when question is CAR button1 = A button2 = R button3 = C when I click button3 button1 = INVISIBLE edit text = A and when I click button2 edit text = A I want when click on button edit text get text from button and check text in edit text
requires: edit text get char form button, add this code to function , remove last index from array
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.LinearLayout;
import java.util.Random;
public class MainActivity extends AppCompatActivity {
LinearLayout linearlayout;
Button button;
EditText txt;
String Array[]= {"car","blue","red","fox"};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
linearlayout = findViewById(R.id.linearlayout);
txt = findViewById(R.id.txt);
int random = (int) (Math.random() * Array.clone().length);
StringBuilder word = new StringBuilder(Array[random]);
for (int i = 0; i < Array[random].length(); i++) {
char id = 'b';
button = new Button(this);
button.setId(id + i);
linearlayout.addView(button);
int randIndex = new Random().nextInt(word.length());
button.setText("" + word.charAt(randIndex));
word.deleteCharAt(randIndex);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
button.setVisibility(View.INVISIBLE);
txt.setText(txt.getText().toString() + button.getText());
}
});
}
}
}
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.LinearLayout;
import java.util.Random;
public class MainActivity extends AppCompatActivity {
LinearLayout linearlayout;
//Button button; //TODO: is local var!
EditText txt; //Global var
String Array[]= {"car","blue","red","fox"};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
linearlayout = findViewById(R.id.linearlayout);
txt = findViewById(R.id.txt);
int random = (int) (Math.random() * Array.clone().length);
StringBuilder word = new StringBuilder(Array[random]);
for (int i = 0; i < Array[random].length(); i++) {
char id = 'b';
final Button button = new Button(this); //local var
button.setId(id + i);
linearlayout.addView(button);
int randIndex = new Random().nextInt(word.length());
button.setText("" + word.charAt(randIndex));
word.deleteCharAt(randIndex);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
//the problem was here (var button)
button.setVisibility(View.INVISIBLE);
txt.setText(txt.getText().toString() + button.getText());
}
});
}
}
}
Not sure of the questions, but the one thing I did find to be an issue with the code.
txt.setText(txt.getText().toString() + button.getText());
The bolded part doesn't returns a char sequence. Should be the same thing as the edit text.
button.getText().toString();
My app keeps crashing and gives me a:
java.lang.NumberFormatException: empty String
Also says this
FATAL EXCEPTION: main
Process: com.example.ayyan.jellybeanestimator, PID: 2966
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.ayyan.jellybeanestimator/com.example.ayyan.jellybeanestimator.MainActivity}: java.lang.NumberFormatException: empty String
package com.example.ayyan.jellybeanestimator;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;
import android.widget.EditText;
import android.widget.Button;
import android.view.View;
public class MainActivity extends AppCompatActivity {
EditText jellyBeanLength, jellyBeanDiameter, jarSizeVolume;
double jellybeantall, jellybeanfat, jellybeanspace, volumeOfOneJellyBean, volumeofBeans;
final double loadFactor = .698;
TextView answer;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
jellyBeanLength = (EditText) findViewById (R.id.length);
jellyBeanDiameter = (EditText) findViewById (R.id.diameter);
jarSizeVolume = (EditText) findViewById (R.id.jarsize);
jellybeantall = Double.parseDouble(jellyBeanLength.getText().toString());
jellybeanfat = Double.parseDouble(jellyBeanDiameter.getText().toString());
jellybeanspace = Double.parseDouble(jarSizeVolume.getText().toString());
answer = (TextView) findViewById (R.id.answer);
Button calculate = (Button) findViewById (R.id.calculate);
calculate.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
volumeOfOneJellyBean = ((3.14159265359/6)*(jellybeanfat*jellybeanfat)*jellybeantall);
volumeofBeans = (jellybeanspace*loadFactor)/volumeOfOneJellyBean;
int jellyguess = (int) (volumeofBeans);
answer.setText("You have this amount of beans in your jar" + jellyguess);
}
});
}
}
jellybeantall = Double.parseDouble(jellyBeanLength.getText().toString());
jellybeanfat = Double.parseDouble(jellyBeanDiameter.getText().toString());
jellybeanspace = Double.parseDouble(jarSizeVolume.getText().toString());
All your EditTexts start as empty. You can't getText() in onCreate, you have to do it in onClick
calculate.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
jellybeantall = Double.parseDouble(jellyBeanLength.getText().toString());
jellybeanfat = Double.parseDouble(jellyBeanDiameter.getText().toString());
jellybeanspace = Double.parseDouble(jarSizeVolume.getText().toString());
volumeOfOneJellyBean = ((3.14159265359/6)*(jellybeanfat*jellybeanfat)*jellybeantall);
volumeofBeans = (jellybeanspace*loadFactor)/volumeOfOneJellyBean;
int jellyguess = (int) (volumeofBeans);
answer.setText("You have this amount of beans in your jar" + jellyguess);
}
});
Note: when volumeOfOneJellyBean == 0, you'll get a division by zero error
So I am running a tutorial app, and it all works except when I try to run the bellow class, however I don't get errors in the code so I was wondering if anyone could help if there is maybe something wrong with the code.
Also on a side not when programming for example you type say: android: in the xml or something. in java how come I don't get the drop down menu with all the options of what can go after?
code:
package com.example.learn.tam;
import java.util.Random;
import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.text.InputType;
import android.view.Gravity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.ToggleButton;
public class textplay extends Activity implements View.OnClickListener{
Button chkCommand;
ToggleButton passToggle;
EditText input;
TextView display;
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.text);
holder();
passToggle.setOnClickListener(this);
chkCommand.setOnClickListener(this);
}
private void holder() {
Button chkCommand = (Button) findViewById(R.id.bResults);
passToggle = (ToggleButton) findViewById(R.id.tbPassword);
input = (EditText) findViewById(R.id.etCommands);
display = (TextView) findViewById(R.id.tvResults);
}
#Override
public void onClick(View v) {
switch(v.getId()){
case R.id.bResults:
String check = input.getText().toString();
display.setText(check);
if(check.contentEquals("left")){
display.setGravity(Gravity.LEFT);
}
else if(check.contentEquals("center")) {
display.setGravity(Gravity.CENTER);
}
else if(check.contentEquals("right")){
display.setGravity(Gravity.RIGHT);
}
else if(check.contentEquals("blue")){
display.setTextColor(Color.BLUE);
}
else if(check.contentEquals("WTF")){
Random crazy = new Random();
display.setText("WTF!!!!");
display.setTextSize(crazy.nextInt(75));
display.setTextColor(Color.rgb(crazy.nextInt(265),crazy.nextInt(265),crazy.nextInt(265)));
switch(crazy.nextInt(3)){
case 0:
display.setGravity(Gravity.LEFT);
break;
case 1:
display.setGravity(Gravity.CENTER);
break;
case 2:
display.setGravity(Gravity.RIGHT);
break;
}
}
else{
display.setText("Invalid");
display.setGravity(Gravity.CENTER);
display.setTextColor(Color.WHITE);
}
break;
case R.id.tbPassword:
if (passToggle.isChecked() == true){
input.setInputType(InputType.TYPE_CLASS_TEXT | InputType.TYPE_TEXT_VARIATION_PASSWORD);
}else{
input.setInputType(InputType.TYPE_CLASS_TEXT);
}
break;
}
}
}
Change:
private void holder() {
Button chkCommand = (Button) findViewById(R.id.bResults);
passToggle = (ToggleButton) findViewById(R.id.tbPassword);
input = (EditText) findViewById(R.id.etCommands);
display = (TextView) findViewById(R.id.tvResults);
}
To
private void holder() {
chkCommand = (Button) findViewById(R.id.bResults);
passToggle = (ToggleButton) findViewById(R.id.tbPassword);
input = (EditText) findViewById(R.id.etCommands);
display = (TextView) findViewById(R.id.tvResults);
}
By declaring a new variable with the same name, you were hiding the class field. Due to this, the class level chkCommand remained null, and gave you an exception when you tried to use chkCommand.setOnClickListener(this);.