Develop Reference

Not finding why output to TextView is NaN

I've been trying for some days now to figure out why I am not getting a proper output from my app. No errors are showing up in logcat to explain why the output is "NaN" and not the value I'm attempting o calculate. Could someone show me the mistake(s) that I've made? It's a calculator app for my final year school project and I've tried to rectify the issue albeit without much success.
Here is the Main class for the app.
I've tried pretty much anything that has been suggested in various forums for similar issues.
public String educationStr, ethnicity, ldlStr, hdlStr, ageStr, tcStr, sysBPStr, diaBPStr;
public int married=0, education=0, educationSec=0, educationTert=0;
public int smoker=0, ethnicityChk=0;
public int highCholesterol=0;
public int atrialFibrillation=0;
public int familialCVD=0;
public int hypertension=0;
public int sex=0;
public int age=0;
public double tcVal = 0;
public double hdlVal=0;
public double ldlVal = 0;
public int sysBPval = 0;
public int diaBPval = 0;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_launch_calculator);
//spinner for sex choices
Spinner spinnerSex = findViewById(R.id.sexSelect);
ArrayAdapter<CharSequence> adapterSex = ArrayAdapter.createFromResource(this, R.array.SexChoices, simple_spinner_item);
adapterSex.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinnerSex.setAdapter(adapterSex);
spinnerSex.setOnItemSelectedListener(this);
//spinner for marriage choices
Spinner spinnerMarried = findViewById(R.id.marriedSelect);
ArrayAdapter<CharSequence> adapterMarried = ArrayAdapter.createFromResource(this, R.array.YN, simple_spinner_item);
adapterMarried.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinnerMarried.setAdapter(adapterMarried);
spinnerMarried.setOnItemSelectedListener(this);
//spinner for Ethnicity
Spinner spinnerEthnicity = findViewById(R.id.ethnicitySelect);
ArrayAdapter<CharSequence> adapterEthnicity = ArrayAdapter.createFromResource(this, R.array.EthnicChoices, simple_spinner_item);
adapterEthnicity.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinnerEthnicity.setAdapter(adapterEthnicity);
spinnerEthnicity.setOnItemSelectedListener(this);
//spinner for education
Spinner spinnerEducation = findViewById(R.id.EduLevelSpin);
ArrayAdapter<CharSequence> adapterEducation = ArrayAdapter.createFromResource(this, R.array.EduLevel, simple_spinner_item);
adapterEducation.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinnerEducation.setAdapter(adapterEducation);
spinnerEducation.setOnItemSelectedListener(this);
//spinner for smoking history
Spinner spinnerSmoker = findViewById(R.id.smokerSelect);
ArrayAdapter<CharSequence> adapterSmoker = ArrayAdapter.createFromResource(this, R.array.smoke, simple_spinner_item);
adapterSmoker.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinnerSmoker.setAdapter(adapterSmoker);
spinnerSmoker.setOnItemSelectedListener(this);
//spinner for family health --> high cholesterol
Spinner spinnerHighCholesterol = findViewById(R.id.highCholesterolSelect);
ArrayAdapter<CharSequence> adapterHighCholesterol = ArrayAdapter.createFromResource(this, R.array.YN, simple_spinner_item);
adapterHighCholesterol.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinnerHighCholesterol.setAdapter(adapterHighCholesterol);
spinnerHighCholesterol.setOnItemSelectedListener(this);
//spinner for family health --> A Fib
Spinner spinnerAFib = findViewById(R.id.atrialFibrillationSelect);
ArrayAdapter<CharSequence> adapterAFib =
ArrayAdapter.createFromResource(this, R.array.YN, simple_spinner_item);
adapterAFib.setDropDownViewResource
(android.R.layout.simple_spinner_dropdown
item);
spinnerAFib.setAdapter(adapterAFib);
spinnerAFib.setOnItemSelectedListener(this);
//spinner for family health --> Hypertension
Spinner spinnerHypertension = findViewById(R.id.HBPSpinSelect);
ArrayAdapter<CharSequence> adapterHypertension =
ArrayAdapter.createFromResource(this, R.array.YN,
simple_spinner_item);
adapterHypertension.setDropDownViewResource
(android.R.layout.simple_spinner_dropdown_item);
spinnerHypertension.setAdapter(adapterHypertension);
spinnerHypertension.setOnItemSelectedListener(this);
//spinner for family health --> Hypertension
Spinner spinnerFamilialCVD = findViewById(R.id.familialCVDSpin);
ArrayAdapter<CharSequence> adapterFamilialCVD =
ArrayAdapter.createFromResource(this, R.array.YN,
simple_spinner_item);
adapterFamilialCVD.setDropDownViewResource
(android.R.layout.simple_spinner_dropdown_item);
spinnerFamilialCVD.setAdapter(adapterFamilialCVD);
spinnerFamilialCVD.setOnItemSelectedListener(this);
//declaring button
final Button BtnSave = findViewById(R.id.btnSaveNsend);
BtnSave.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
switch(v.getId()){
case R.id.ageEnter:
EditText enterAge = findViewById(R.id.ageEnter);
ageStr = enterAge.getText().toString();
age = Integer.valueOf(ageStr);
break;
case R.id.sysBPEnter:
EditText enterSys = findViewById(R.id.sysBPEnter);
sysBPStr = enterSys.getText().toString();
sysBPval = Integer.valueOf(sysBPStr);
break;
case R.id.diaBPEnter:
EditText enterDia = findViewById(R.id.diaBPEnter);
diaBPStr = enterDia.getText().toString();
diaBPval = Integer.valueOf(diaBPStr);
break;
case R.id.tcEnter:
EditText enterTC = findViewById(R.id.tcEnter);
tcStr = enterTC.getText().toString();
tcVal = Integer.valueOf(tcStr);
break;
case R.id.hdlEnter:
EditText enterHDL = findViewById(R.id.hdlEnter);
hdlStr = enterHDL.getText().toString();
hdlVal = Integer.valueOf(hdlStr);
break;
case R.id.ldlEnter:
EditText enterLDL = findViewById(R.id.ldlEnter);
ldlStr = enterLDL.getText().toString();
ldlVal = Integer.valueOf(ldlStr);
}
if (ethnicityChk == 1){
Intent RiskCalc1 = new
Intent(getApplicationContext(),displayLinRiskResult.class);
startActivity(RiskCalc1);
} else if (ethnicityChk == 2){
Intent RiskCalc2 = new
Intent(getApplicationContext(),displayDiscrimRiskResult.class);
startActivity(RiskCalc2);
}
}
});
}
#Override
public void onItemSelected(AdapterView<?>
adapterView, View view, int i, long l) {
switch(adapterView.getId()){
case R.id.sexSelect:
String sexStr = adapterView.getSelectedItem().toString();
if (sexStr.equalsIgnoreCase("female")){
sex = 1;
}
else if (sexStr.equalsIgnoreCase("male")){
sex = 0;
}
//Toast.makeText(adapterView.getContext(), sex,
Toast.LENGTH_SHORT).show();
break;
case R.id.marriedSelect:
String marriedStr = adapterView.getSelectedItem().toString();
if (marriedStr.equalsIgnoreCase("YES")){
married = 1;
}
else if (marriedStr.equalsIgnoreCase("NO")){
married = 0;
}
//Toast.makeText(adapterView.getContext(), married,
Toast.LENGTH_SHORT).show();
break;
case R.id.smokerSelect:
String smokerStr = adapterView.getSelectedItem().toString();
if (ethnicity.equalsIgnoreCase("Afro-Caribbean"))
{if (smokerStr.equalsIgnoreCase("Smoker")){
smoker = 1;
}
else if (smokerStr.equalsIgnoreCase("Non-smoker")){
smoker = 0;
} }
else if (ethnicity.equalsIgnoreCase("Mixed-Caribbean")){
{if (smokerStr.equalsIgnoreCase("Smoker")){
smoker = 0;
}
else if (smokerStr.equalsIgnoreCase("Ex-smoker")){
smoker = 1;
} }}
// Toast.makeText(adapterView.getContext(), smokerStr,
Toast.LENGTH_SHORT);
break;
case R.id.ethnicitySelect:
ethnicity = (String) adapterView.getSelectedItem();
if (ethnicity.equals("Afro-Caribbean")||
(ethnicity.equals("Indo-Caribbean"))){
ethnicityChk = 1;
}
else if (ethnicity.equals("Mixed-Caribbean")){
ethnicityChk = 2;
}
//Toast.makeText(adapterView.getContext(), ethnicityStr,
Toast.LENGTH_SHORT);
break;
case R.id.EduLevelSpin:
educationStr = (String) adapterView.getSelectedItem();
//Toast.makeText(adapterView.getContext(),education,
Toast.LENGTH_SHORT);
if (educationStr.equalsIgnoreCase("Secondary")){
educationSec = 1;
educationTert = 0;
education = 1;
}
else if (educationStr.equalsIgnoreCase("Tertiary")){
educationSec = 1;
educationTert = 1;
education = 1;
}
else {
education = 1;
educationSec = 0;
educationTert = 0;
}
break;
case R.id.highCholesterolSelect:
String highCholesterolStr = (String)
adapterView.getSelectedItem();
if (highCholesterolStr.equalsIgnoreCase("YES")){
highCholesterol = 1;
}
else if (highCholesterolStr.equalsIgnoreCase("NO")){
highCholesterol = 0;
}
//Toast.makeText(adapterView.getContext(),
highCholesterolStr,Toast.LENGTH_SHORT);
break;
case R.id.atrialFibrillationSelect:
String AfibStr = (String) adapterView.getSelectedItem();
if (AfibStr.equalsIgnoreCase("YES")){
atrialFibrillation = 1;
}
else if (AfibStr.equalsIgnoreCase("NO")){
atrialFibrillation = 0;
}
// Toast.makeText(adapterView.getContext(),
AfibStr,Toast.LENGTH_SHORT);
break;
case R.id.HBPSpinSelect:
String HBPstr = (String) adapterView.getSelectedItem();
if (HBPstr.equalsIgnoreCase("YES")){
hypertension = 1;
}
else if (HBPstr.equalsIgnoreCase("NO")){
hypertension = 0;
}
//Toast.makeText(adapterView.getContext(),
HBPstring,Toast.LENGTH_SHORT);
break;
case R.id.familialCVDSpin:
String famCVDStr = (String) adapterView.getSelectedItem();
if (famCVDStr.equalsIgnoreCase("YES")){
familialCVD = 1;
}
else if (famCVDStr.equalsIgnoreCase("NO")){
familialCVD = 0;
}
//Toast.makeText(adapterView.getContext(),
famCVDString,Toast.LENGTH_SHORT);
break;
}
}
#Override
public void onNothingSelected(AdapterView<?> adapterView) {
}
Here is the class used to output the result:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.display_lin_risk);
TextView RiskViewLinRisk = findViewById(R.id.RiskViewLinRisk);
float LinRisk = (float) ((-16.13) + (0.119 * age) - (1.333 * sex)
+ (1.502 * married) + (2.619 * smoker) - (0.555 * (tcVal /
hdlVal)) + (0.026 *ldlVal) + (1.952 * highCholesterol) + (2.867
* atrialFibrillation) + (4.272 * hypertension) + (1.957 *
familialCVD));
String LinRiskStr = Float.toString(LinRisk);
RiskViewLinRisk.setText(LinRiskStr);
}

Just to give a bit more context than in the comments, double division in Java can return a NaN which stands for "not a number". This happens when you divide 0.0 by 0.0, but can also happen if you take the square root of a negative number.
Because Java implements the IEEE standard for NaN, it guarantees that NaN is never equal to itself. In fact, the only comparison that returns true is NaN != NaN. There's a very famous puzzle:
float x = //...
if (x != x)
System.out.println("Foo");
The question is "initialize x to a value which guarantees that Foo is printed". The answer is Float.NaN, because NaN is not equal to itself. Also, this is the only value that could work. All other values in Java would not solve this puzzle.
For this reason, a solution used lots of times to identify if a number is NaN is:
public boolean isNan(float x) {
return x != x;
}
(Since Java 8 a method exists in the standard lib to verify if a number is NaN)
You could use this to check the result of the division you're doing and avoid displaying NaN when you don't want to.
To display the values after you click on the button you have to run again the calculation and display it. I recommend extracting it into a method:
public float calculateLinRisk() {
return (float) ((-16.13) + (0.119 * age) - (1.333 * sex)
+ (1.502 * married) + (2.619 * smoker) - (0.555 * (tcVal /
hdlVal)) + (0.026 *ldlVal) + (1.952 * highCholesterol) + (2.867
* atrialFibrillation) + (4.272 * hypertension) + (1.957 *
familialCVD));
}
public void displayCurrentLinRisk() {
// This can also be a field in the main activity to
// avoid multiple calls to findViewById
TextView RiskViewLinRisk = findViewById(R.id.RiskViewLinRisk);
float LinRisk = calculateLinRisk()
String LinRiskStr = Float.toString(LinRisk);
RiskViewLinRisk.setText(LinRiskStr);
}
onCreate becomes:
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.display_lin_risk);
displayCurrentLinRisk();
}
Then you can use this at the end of click listener
BtnSave.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// ...
displayCurrentLinRisk();
}
}

Cart Count increment & decrement while clicking button

I populates cart items into the list using cursor adapter. My ListView item has
Price TextView
Product Name TextView
Count TextView
Increment Button
Decrement Buttton
When I click the increment / decrement button the value is incremented/ decremented in a certain condition of AFTER TOUCHING THE LISTVIEW ROW,otherwise the count is not changed.
In some case, if I click the 1st row increment button ,item count is incremented in 2nd row.
NOTE:
1. I am populating List using Cursor Adapter.
2. Using Increment & Decrement clicklistener in activity class.
Here is my code:
cartList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(final AdapterView<?> parent, View itemView, final int position, final long rowId) {
txt_cartProduct = (TextView) itemView.findViewById(R.id.cartProduct);
txt_cartQuantity = (TextView) itemView.findViewById(R.id.cartQuantity);
txt_cartPrice = (TextView) itemView.findViewById(R.id.cartPrice);
txt_cartPriceDum = (TextView) itemView.findViewById(R.id.cartPriceDum);
txt_cartCount = (TextView) itemView.findViewById(R.id.cartCount);
img_ivDecrease = (ImageView) itemView.findViewById(R.id.ivDecrease);
img_ivIncrease = (ImageView) itemView.findViewById(R.id.ivIncrease);
but_addTowish = (Button) itemView.findViewById(R.id.addTowish);
but_remove = (Button) itemView.findViewById(R.id.remove);
img_ivIncrease.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
strPrice = txt_cartPrice.getText().toString();
price = Integer.parseInt(strPrice);
int counter = 0;
try {
counter = Integer.parseInt(txt_cartCount.getText().toString());
} catch (NumberFormatException e) {
e.printStackTrace();
}
counter++;
if (counter > 0) {
txt_cartCount.setText(Integer.toString(counter));
txt_cartPrice.setVisibility(View.GONE);
txt_cartPriceDum.setVisibility(View.VISIBLE);
quantity = txt_cartCount.getText().toString();
total = (Integer.parseInt(quantity)) * (price);
netA = String.valueOf(total);
sum += price;
if (sum == 0) {
netAmount = Integer.parseInt(txt_cartPriceDum.getText().toString());
}
netAmount = sum;
Log.e("Sum is", String.valueOf(sum));
txt_cartPriceDum.setText(String.valueOf(total));
cartCount = Integer.parseInt(quantity);
Toast.makeText(context, "netAmount" + netAmount + "\n" + "Total" + total, Toast.LENGTH_SHORT).show();
if (counter == 1) {
cartPrice = price;
cartSum = sum;
}
if (counter == 0) {
cartPrice = 0;
cartSum = 0;
cartCount = 0;
Toast.makeText(context, "Minimum Item is 1", Toast.LENGTH_SHORT).show();
}
int count_check = 1;
if (count_check >= position) {
count_check++;
} else if (count_check == 0) {
Toast.makeText(context, "Minimum Item is 1", Toast.LENGTH_SHORT).show();
}
}
}
});
img_ivDecrease.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
strPrice = txt_cartPrice.getText().toString();
price = Integer.parseInt(strPrice);
int counter = 0;
try {
counter = Integer.parseInt(txt_cartCount.getText().toString());
} catch (NumberFormatException e) {
e.printStackTrace();
}
counter--;
if (counter > 0) {
txt_cartCount.setText(Integer.toString(counter));
txt_cartPrice.setVisibility(View.GONE);
txt_cartPriceDum.setVisibility(View.VISIBLE);
quantity = txt_cartCount.getText().toString();
total = (Integer.parseInt(quantity)) * (price);
netA = String.valueOf(total);
sum -= price;
if (sum == 0) {
netAmount = Integer.parseInt(txt_cartPriceDum.getText().toString());
}
Log.e("Sum - is", String.valueOf(sum));
txt_cartPriceDum.setText(String.valueOf(total));
cartCount = Integer.parseInt(quantity);
Toast.makeText(context, "netAmount" + netAmount + "\n" + "Total" + total, Toast.LENGTH_SHORT).show();
if (counter == 1) {
cartPrice = price;
cartSum = sum;
}
if (counter == 0) {
cartPrice = 0;
cartSum = 0;
cartCount = 0;
}
}
}
});
}
});

You can use setTag() and getTag() methods for saving the counter value in each list item.
Refer this answer for more details.

two array dimensional ArrayIndexOutOfBoundException and NullPointerException

i wrote a code for calculating some weights. they are integer weights.
and i need to save them in every time the button is clicked.
please help me. i cant see why the compiler gives me an error when i try to push the button for the second time. here is my complete code:
public class TrainingActivity extends Activity {
private EditText etIn1, etIn2, etDesired;
private TextView prevInput;
int W[][] = new int[2][];
int X[][] = new int[30][];
int w0=0, w1=0, w2=0, p=1, sum=0, clicks=0;
private Button nxtData;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.training_activity);
View backgroundImage = findViewById(R.id.background);
Drawable background = backgroundImage.getBackground();
background.setAlpha(40);
etIn1= (EditText) findViewById(R.id.etInput1);
etIn2 = (EditText) findViewById(R.id.etInput2);
etDesired = (EditText) findViewById(R.id.etDesired);
prevInput = (TextView) findViewById(R.id.prevInput);
nxtData = (Button) findViewById(R.id.nextData);
nxtData.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
int sum = 0;
++clicks;
int intetIn1 = Integer.parseInt(etIn1.getText().toString());
int intetIn2 = Integer.parseInt(etIn2.getText().toString());
int intetDesired = Integer.parseInt(etDesired.getText().toString());
X[clicks-1] = new int[] {intetIn1, intetIn2, 1};
prevInput.setText("Last Inputs: (" + intetIn1 + ", " + intetIn2 +
", " + intetDesired + ")");
if(clicks == 1) {
if(intetDesired == 1) {
W[0] = new int[] {intetIn1, intetIn2, 1};
W[1] = W[0];
} else if(intetDesired == (-1)){
W[0] = new int[] {-intetIn1, -intetIn2, -1};
W[1] = W[0];
}
} else if(clicks > 1) {
for(int i=0; i<3; i++){
sum = sum + W[clicks-1][i] * X[clicks-1][i];
} if(sum>0 && intetDesired==1) {
W[clicks] = W[clicks-1];
} else if(sum<0 && intetDesired==(-1)) {
W[clicks] = W[clicks-1];
} else if(sum<=0 && intetDesired==1) {
for(int i=0; i<3; i++) {
W[clicks][i] = W[clicks-1][i] + X[clicks-1][i];
}
} else if(sum>=0 && intetDesired==(-1)) {
for(int i=0; i<3; i++) {
W[clicks][i] = W[clicks-1][i] - X[clicks-1][i];
}
}
}
etIn1.setText("");
etIn2.setText("");
etDesired.setText("");
}
});
}}
and here is the exception it throws:
java.lang.ArrayIndexOutOfBoundsException: length=2; index=2
UPDATEEEEEEEE
i fixed the problem with arrayindexoutofboundexception by changing W[2][] to W[20][]. but in some clicks it gives me this error:
java.lang.NullPointerException
and it's not clear in which clicks. sometimes it's in the second click. or some times it's in fourth click. please help.

W[clicks] = W[clicks - 1];
in above line, you have get error because you have only define size of the array
int W[][] = new int[2][];
so it assigned W[0][] and W[1][] only
When click on second time variable clicks value is 2 then compiler gives ArrayIndexOutOfBoundException
EDITED.............................................................
you have got null value because of your bad logic and not proper way to build two dimensional array. Pls use debug tool to find the actual problem to implement logic and use two dimensional array like below example in java or android:
List<List<Integer>> triangle = new ArrayList<List<Integer>>();
List<Integer> row1 = new ArrayList<Integer>(1);
row1.add(2);
triangle.add(row1);
List<Integer> row2 = new ArrayList<Integer>(2);
row2.add(3);row2.add(4);
triangle.add(row2);
triangle.add(Arrays.asList(6,5,7));
triangle.add(Arrays.asList(4,1,8,3));
System.out.println("Size = "+ triangle.size());
for (int i=0; i<triangle.size();i++)
System.out.println(triangle.get(i));

My code throws ArrayIndexOutOfBoundException but i think it's ok

here is my code:
public class TrainingActivity extends Activity {
private EditText etIn1, etIn2, etDesired;
private TextView prevInput;
int W[][] = new int[2][];
int X[][] = new int[30][];
int w0=0, w1=0, w2=0, p=1, sum=0, clicks=0;
private Button nxtData;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.training_activity);
View backgroundImage = findViewById(R.id.background);
Drawable background = backgroundImage.getBackground();
background.setAlpha(40);
etIn1= (EditText) findViewById(R.id.etInput1);
etIn2 = (EditText) findViewById(R.id.etInput2);
etDesired = (EditText) findViewById(R.id.etDesired);
prevInput = (TextView) findViewById(R.id.prevInput);
nxtData = (Button) findViewById(R.id.nextData);
nxtData.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
int sum = 0;
++clicks;
int intetIn1 = Integer.parseInt(etIn1.getText().toString());
int intetIn2 = Integer.parseInt(etIn2.getText().toString());
int intetDesired = Integer.parseInt(etDesired.getText().toString());
X[clicks-1] = new int[] {intetIn1, intetIn2, 1};
prevInput.setText("Last Inputs: (" + intetIn1 + ", " + intetIn2 +
", " + intetDesired + ")");
if(clicks == 1) {
if(intetDesired == 1) {
W[0] = new int[] {intetIn1, intetIn2, 1};
W[1] = W[0];
} else if(intetDesired == (-1)){
W[0] = new int[] {-intetIn1, -intetIn2, -1};
W[1] = W[0];
}
} else if(clicks > 1) {
for(int i=0; i<3; i++){
sum = sum + W[clicks-1][i] * X[clicks-1][i];
} if(sum>0 && intetDesired==1) {
W[clicks] = W[clicks-1];
} else if(sum<0 && intetDesired==(-1)) {
W[clicks] = W[clicks-1];
} else if(sum<=0 && intetDesired==1) {
for(int i=0; i<3; i++) {
W[clicks][i] = W[clicks-1][i] + X[clicks-1][i];
}
} else if(sum>=0 && intetDesired==(-1)) {
for(int i=0; i<3; i++) {
W[clicks][i] = W[clicks-1][i] - X[clicks-1][i];
}
}
}
Toast.makeText(getApplicationContext(), "" + clicks,
Toast.LENGTH_SHORT).show();
System.out.println(X[0][0]);
etIn1.setText("");
etIn2.setText("");
etDesired.setText("");
}
});
}}
and here is the Exception:
java.lang.ArrayIndexOutOfBoundsException: length=2; index=2
the clicks is the number of times that user click the button. at first it's ok but when i try and add some more inputs it crashes. can you tell why this is happening?

index of array is always less than length as index starts form 0 whereas length from 1 therefore X[clicks-1] is causing the problem

What is the initial value of click variable.
Can you post more code related. And for the first time if click is 0 then
X[clicks-1] = new int[] {intetIn1, intetIn2, 1};
this says you are store these value at click-1 th position which is not even initialized.. so
int X[] = new int[]{intetIn1, intetIn2, 1};
would be better.

Android: If/Else statement makes app crash

I'm trying to tell if an android int is null by using If/Else
public void onClick(View v) {
EditText min = (EditText) findViewById(R.id.EditText01);
EditText max = (EditText) findViewById(R.id.maxnum);
EditText res = (EditText) findViewById(R.id.res);
int myMin = Integer.parseInt(min.getText().toString());
int myMax = Integer.parseInt(max.getText().toString());
String minString = String.valueOf(myMin);
String maxString = String.valueOf(myMax);
int f = (int) ((Math.random()*(myMax-myMin+1))+myMin);
if (minString.equals(""))
{
// Do Nothing
}
if (maxString.equals(""))
{
// Do Nothing
}
res.setText(String.valueOf(f));
There are no any errors, but when I'm running the app its crashing when im pressing the button.
I'm also trying to use null instead of "":
if (minString.equals(null))
{
// Do Nothing
}
if (maxString.equals(null))
{
// Do Nothing
}
And i have a crash.
Please help me!!!

public boolean equals (Object object)
Compares the specified object to this string and returns true if they are equal. The object must be an instance of string with the same characters in the same order.
So its returning error so if you want to check if its null then use == operator on the object.
if (maxString == null )
Use
int myMin = 0;
int myMax = 0;
if(min.getText().toString()!="")
myMin = Integer.parseInt(min.getText().toString());
if(max.getText().toString()!="")
myMax = Integer.parseInt(max.getText().toString());
String minString = String.valueOf(myMin);
String maxString = String.valueOf(myMax);
int f = (int) ((Math.random()*(myMax-myMin+1))+myMin);
if (minString.equals(""))
{
// Do Nothing
}
if (maxString.equals(""))
{
// Do Nothing
}

do if (maxString == null )
{
// do something
}

int variables can't be null
If a null is to be converted to int, then it is the converter which decides whether to set 0, throw exception, or set another value (like Integer.MIN_VALUE)
So if you convert int to string again you cannot get null value.

check = input.getText().toString();
try {
if (!check.equals("null")) {
int max = Integer.parseInt(input.getText().toString());
int constant1 = 1;
int constant2 = 1;
int nextNumber = 0;
int count = 0;
String fibResult = "";
for (int i = 0; i <= max; i++) {
fibResult += "F" + count + "=" + nextNumber + "\n";
constant1 = constant2;
constant2 = nextNumber;
nextNumber = constant1 + constant2;
count++;
}
dspResults.setText("\n" + fibResult);
} else {
dspResults.setVisibility(View.VISIBLE);
dspResults.setText("Invalid");
dspResults.setText(Gravity.CENTER);
dspResults.setTextColor(Color.DKGRAY);
}
} catch (IllegalArgumentException e) {
e.printStackTrace();
}

public void onClick(View v) {
EditText min = (EditText) findViewById(R.id.EditText01);
EditText max = (EditText) findViewById(R.id.maxnum);
EditText res = (EditText) findViewById(R.id.res);
int myMin = Integer.parseInt(min.getText().toString());
int myMax = Integer.parseInt(max.getText().toString());
String minString = String.valueOf(myMin);
String maxString = String.valueOf(myMax);
int f = (int) ((Math.random()*(myMax-myMin+1))+myMin);
{
if (minString.equals(""))
{
// Do Nothing
res.setText(String.valueOf(f));
return false;
}
else if (maxString.equals(""))
{
// Do Nothing
res.setText(String.valueOf(f));
return false;
}
else
res.setText(String.valueOf(f));
return true ;
}