This question already has answers here:
Reverse a string in Java
(36 answers)
Closed 9 years ago.
I just want to reverse a inputted String by using for loop.
I have tried the following code below. [ its full of mistake i think.. cause i dont know how to convert things to array or to string in this problem ]. So anyone please help me the coding here...
public class Main extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
TextView tv = (TextView) findViewById(R.id.textView1);
EditText input_string =(EditText) findViewById(R.id.editText1);
final String orig = input_string.getText().toString();
Button rev = (Button) findViewById(R.id.button1);
rev.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View arg0) {
int limit = orig.length();
for(int i=limit;i<=limit;i--)
{
String[] neww = orig[i].;
}
tv.setText(neww);
}}) }}
Something like this is what you're looking for.
String x = "A string";
String y = "";
for(int i = x.length()-1; i >= 0; i--){
y=y + x.charAt(i);
}
Your new string will be stored in the variable y.
Related
This question already has answers here:
How to convert TextView value to Integer
(2 answers)
Closed 2 years ago.
For the if statements part, it has a red mark. and it says, operator '+' can't be applied to 'TextView', 'int'. And I have a no clue what to do with that. Am I not able to use < kind of symbol for if statement?
public class result extends AppCompatActivity {
Button button3;
TextView message;
TextView SMM;
TextView BFM;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_result);
SMM = (TextView) findViewById(R.id.SMM);
BFM = (TextView) findViewById(R.id.BFM);
button3 = (Button) findViewById(R.id.button3);
button3.setClickable(true);
button3.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
String musclemass = SMM.getText().toString();
String fatmass = BFM.getText().toString();
Intent intent = new Intent();
intent.putExtra("musclemass", musclemass);
intent.putExtra("fatmass", fatmass);
if(musclemass < fatmass + 50){
message.setText("kid");
}
if(musclemass > fatmass + 50){
message.setText("adult");
}
}
});
}
}
Change
if(SMM < BFM + 50){
to
if(Integer.valueOf(SMM.getText().toString())< Integer.valueOf(BFM.getText().toString())+ 50){
and similar at other locations as TextView and integer are two different datatypes. You have to first get Integer value and then compare them
Seem you don't understand what is the TextView, SMM in your case for example. You already get the string musclemass from SMM(TextView), right?
How would you describe this, SMM.getText().toString ?
Assume that you know you got a string.
Why don't you (try to) convert this string to int (Integer). You have to screen and make sure that the input is really an Integer, not other characters.
Since TextView (BFM in this case) is not an integer number, it can't be added (+) with 50.
You would better use EditText instead of TextView.
Closed. This question needs details or clarity. It is not currently accepting answers.
Want to improve this question? Add details and clarify the problem by editing this post.
Closed 8 years ago.
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I'm doing a word shuffle app on android studio for a class project. I need help understanding how I can get the users input and match it to the correct String answer. I tried a few approaches and have fallen short. I tried using an if(word.equals(userAnswer)) statement but having a hard time understanding it. How can I write the if statement for text input/output to match my answer in android studio?
(Optional question) Also is public void OnClick(View v) a good approach or should I go with something else?
Any help will be greatly appreciated. Thanks in advance!
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
private EditText userAnswer;
private TextView answerOutput;
private TextView scrambledWord;
public void OnClick(View v){
scrambledWord = (TextView) findViewById(R.id.scrambledWord);
userAnswer = (EditText) findViewById(R.id.answerInput);
answerOutput = (TextView) findViewById(R.id.answerOutput);
Button button = (Button) v;
String word = "Animals"; // scan for word
ArrayList<Character> chars = new ArrayList<Character>(word.length()); // gets array with length of word
for ( char c : word.toCharArray() ) {
chars.add(c);
}
Collections.shuffle(chars); //shuffles the characters
char[] shuffled = new char[chars.size()];
for ( int i = 0; i < shuffled.length; i++ ) {
shuffled[i] = chars.get(i);
}
String shuffledWord = new String(shuffled);
if (word.equals(userAnswer)){
answerOutput.setText("Correct!!");
} else {
answerOutput.setText("Sorry try again.");
}
}
This will allow you to determine if they are the same
if(word.equalsIgnoreCase(userAnswer.getText().toString())) {
answerOutput.setText("Correct");
}
However, generally speaking you have a much larger problem, unless it's in code somewhere that you aren't showing us.
Somewhere in your activity onCreate/onStart you want to initialize your button with whatever view it might be.
Button checkAnswer = (Button) findViewById(//whatever your id is)
Then you want to set the onClick listener of the button. With the approach that you are using, it would end up needing two things. First this
public class MainActivity extends Activity implements View.OnClickListener {
Then in you need to set the onClick listener to your Button, probably in OnCreate.
checkAnswer.setOnClickListener(this);
Then your onClick would look something like
#Override
public void onClick(View v) {
if (word.equals(userAnswer)){
answerOutput.setText("Correct!!");
}
else {
answerOutput.setText("Sorry try again.");
}
}
The logic for scrambling the word etc, probably wouldn't be in onClick here.
Also, if you have multiple things you want to set click listeners for you would do something like this
#Override
public void onClick(View v) {
switch(v.getId()) {
case(R.id.//whatever): {
//dosomething
break;
}
}
}
Where you can multiple cases for all of the views that you have set the MainActivity to handle.
Edit: Since you updated your code
public class MainActivity extends Activity implements View.OnClickListener {
private EditText userAnswer;
private TextView answerOutput;
private TextView scrambledWord;
private String word;
private String shuffledWord;
private Button button;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
scrambledWord = (TextView) findViewById(R.id.scrambledWord);
userAnswer = (EditText) findViewById(R.id.answerInput);
answerOutput = (TextView) findViewById(R.id.answerOutput);
createWord();
button = (Button) findViewById(R.id.button);
button.setOnClickListener(this);
}
private void createWord() {
word = "Animals";
ArrayList<Character> chars = new ArrayList<Character>(word.length()); // gets array with length of word
for ( char c : word.toCharArray() ) {
chars.add(c);
}
Collections.shuffle(chars); //shuffles the characters
char[] shuffled = new char[chars.size()];
for ( int i = 0; i < shuffled.length; i++ ) {
shuffled[i] = chars.get(i);
}
shuffledWord = new String(shuffled);
shuffledText.setText(shuffledWord);
}
#Override
public void OnClick(View v){
if (word.equalsIgnoreCase(userAnswer.getText().toString())){
answerOutput.setText("Correct!!");
} else {
answerOutput.setText("Sorry try again.");
}
}
Did you set the onClickListener of the button to your MainActivity?
Your MainActivity should implement OnClickListener too
You need to use userAnswer.getText() to get the answer. Your userAnswer variable currently is of type EditText, which means a check to see if word.equals(userAnswer) will always return false, as they are of different types. Instead, try word.equals(userAnswer.getText()) to check if their answer equals the original word. To check if their answer equals the scrambled word, use shuffledWord.equals(userAnswer.getText()).
This question already has answers here:
java.lang.numberformatexception: invalid double: " "
(6 answers)
Closed 8 years ago.
When I try running my Android App, I get an error saying: java.lang.NumberFormatException: Invalid double: "". This is my code:
public class MainActivity extends Activity {
double score;
EditText gpa;
EditText sat;
EditText act;
Button calc;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
gpa = (EditText) findViewById(R.id.gpa);
String gpaString = gpa.getText().toString();
final double gpaDouble = Double.parseDouble(gpaString);
sat = (EditText) findViewById(R.id.sat);
String satString = sat.getText().toString();
final int satInt = Integer.parseInt(satString);
act = (EditText) findViewById(R.id.act);
String actString = act.getText().toString();
final int actInt = Integer.parseInt(actString);
calc = (Button) findViewById(R.id.calc);
calc.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(actInt/36>satInt/2400){
score = (0.6*gpaDouble*25)+(0.4*(actInt/36)*100);
}else{
score = (0.6*gpaDouble*25)+(0.4*(satInt/2400)*100);
}
}
});
}
}
I essentially want to get numbers from three EditTexts, make one of them into a double and the other two into ints. Then I would use these variables to set the value for another double variable. I am not getting errors before I run the app. I feel that when the EditText field is blank, it will not parse correctly, but I am unsure how to solve this. What is the problem?
Invalid double: "".
you are parsing onCreate() value without putting any default value so the exception
final double gpaDouble = Double.parseDouble(gpaString);
because "" (empty String is not Double)
I know this is a simpleton question, but I am not going to school for java, just learning it online.
how to a have a textview with an initial value of 0. and then everytime you press a button it ads 25 points to the score board.
At first I wanted the button press to add a random number between 42-57 to the score board.
And then how to do convert that int or long to a string to make it fit into a textview and keep the current score, and then add a new score.
EDIT: ok so someone said I should post the code so here it is.. where do i put this..
TextView txv182 = (TextView) findViewById(R.id.welcome);
txv182.setText(toString(finalScore));
Because when I do it, I get an error: The method toString() in the type Object is not applicable for the arguments (int)
public class MainActivity extends Activity {
// Create the Chartboost object
private Chartboost cb;
MediaPlayer mp = new MediaPlayer();
SoundPool sp;
int counter;
int db1 = 0;
Button bdub1;
TextView txv182;
int finalScore;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
txv182 = (TextView) findViewById(R.id.welcome);
finalScore = 100;
sp = new SoundPool(10, AudioManager.STREAM_MUSIC, 0);
db1 = sp.load(this, R.raw.snd1, 1);
bdub1 = (Button) findViewById(R.id.b4DUB1);
bdub1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
if (db1 != 0)
sp.play(db1, 1, 1, 0, 0, 1);
txv182.setText(finalScore);
}
});
First you need to store your score to certain integer variable say score and set it to any initial value you want and use.
TextView tv = (TextView) findViewById(R.id.myTextView);
tv.setText(toString(score));
you do not need to initialize the textview with value just in onclick() of button do score+=25and add text to your textview as above.
hope this helps
It's actually like this..
pernts+=25;
txv182.setText(String.valueOf(pernts));
in android, after the
public class MainActivity extends Activity {
but before..
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
i wrote..
int pernts;
String strI;
so then after the above #Override majigy, i wrote..
strI = "" + pernts;
pernts = 0;
because when i wrote it like.. int pernts = 0; it never worked, forcing me to add final and what not..
any way.. How to convert an integer value to string? anSwered the question..
and so the end was like this
pernts+=25;
txv182.setText(String.valueOf(pernts));
i figured out you have to add a value to the int variable not the string.. i kept wanting to add 25 and i was getting 25252525252525.., instead of 25 50 75 100.. kinda cool actually.. separating the logic of how to "add" 25 .. anyway thanks.. SOF!
30 minutes later... found this.. How can I generate random number in specific range in Android?
..
import android.app.Activity;
public class InsMenu extends Activity {
static TextView txv182;
static int pernts;
Button bdub1;
public static void addPernts() {
int min = 37;
int max = 77;
Random r = new Random();
int i1 = r.nextInt(max - min + 1) + min;
pernts+=i1;
txv182.setText(String.valueOf(pernts));
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.BLAHBLAH);
bdub1 = (Button) findViewById(R.id.b4DUB1);
txv182 = (TextView) findViewById(R.id.welcome);
bdub1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
addPernts();
}
--- i created my first objekt thanks to this too.. http://www.tutorialspoint.com/java/java_methods.htm ..
This is kind of hard to explain. Basically it's kind of like a simple game. I want the people to input their names (currently the submit button is not working correctly) hit submit for each name and when all names are in they hit play. It then opens up the next class. It needs to get the string array from the prior class as well as the number of players. It then needs to select each persons name in order and give them a task to do (which it randomly generates). Then it allows the other people to click a button scoring how they did. (I am not sure how to set up the score system. Not sure if there is a way to assign a score number to a particular array string) I would then like it after 5 rounds to display the winner. If you have any input or could help me out I would be extremely grateful. Thanks for taking the time... here are the two classes i have.
Class 1
public class Class1 extends Activity
{
int players=0;
String names[];
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.class1);
final EditText input = (EditText) findViewById(R.id.nameinput);
Button submitButton = (Button) findViewById(R.id.submit_btn);
submitButton.setOnClickListener(new View.OnClickListener()
{
public void onClick(View submit1)
{
players++;
for(int i=0; i < players; i++)
{
names[i] = input.getText().toString();
input.setText("");
}
}
});
Button doneButton = (Button) findViewById(R.id.done_btn);
doneButton.setOnClickListener(new View.OnClickListener()
{
public void onClick(View done1)
{
Intent done = new Intent(Class1.this, Class2.class);
done.putExtra("players", players);
done.putExtra("names", names[players]);
startActivity(done);
}
});
}
Class 2
public class Class2 extends Activity
{
int players, counter, score, ptasks,rindex;
String[] names, tasks;
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.class2);
Intent game = getIntent();
players = game.getIntExtra("players", 1);
names = game.getStringArrayExtra("names");
Random generator = new Random();
tasks[0]= "task1";
tasks[1]= "task2";
tasks[2]= "task3";
tasks[3]= "task4";
tasks[4]= "task5";
tasks[5]= "task6";
tasks[6]= "task7";
tasks[7]= "task8";
tasks[8]= "task9";
tasks[9]= "task10";
while (counter <5)
{
for (int i = 0; i < players; i++)
{
TextView name1 = (TextView) findViewById(R.id.pname);
name1.setText( names[i]+":");
ptasks = 10;
rindex = generator.nextInt(ptasks);
TextView task = (TextView) findViewById(R.id.task);
task.setText( tasks[rindex]);
}
Button failButton = (Button) findViewById(R.id.fail_btn);
failButton.setOnClickListener(new View.OnClickListener()
{
public void onClick(View failed)
{
//not sure what to put here to get the scores set up
}
});
Button notButton = (Button) findViewById(R.id.notbad_btn);
notButton.setOnClickListener(new View.OnClickListener()
{
public void onClick(View notbad)
{
//not sure what to put here to get the scores set up
}
});
Button champButton = (Button) findViewById(R.id.champ_btn);
champButton.setOnClickListener(new View.OnClickListener()
{
public void onClick(View champp)
{
//not sure what to put here
}
});
counter++;
}
}
I'm sure this thing is riddled with errors. And I'm sorry if it is I'm not that well experienced a programmer. Thanks again
You can pass a string array from one activity to another using a Bundle.
Bundle bundle = new Bundle();
bundle.putStringArray("arrayKey", stringArray);
You can then access this stringArray from the next activity as follows:
Bundle bundle = this.getIntent().getExtras();
String[] stringArray = bundle.getStringArray("arrayKey");
I'm not sure if this is the only thing you intend to do. I hope it helps. Also, to assign a score to a particular string array, assuming your scores are int's you could use a HashMap as follows,
HashMap<String[],int> imageData = new HashMap<String[],int>();
But I'm not sure how you would pass this Map to another activity if you intend to do so.
http://developer.android.com/reference/android/content/Intent.html#putExtra(java.lang.String,%20java.lang.String[])
Use this cheat:
In Class2, convert you array string (tasks) to string (strSavedTask)by adding "|" separator. After that, pass your strSavedTask into Bundle and start to Class1.
When return to Class1, read strSavedTask from Bundle, split it by "|".
That's my cheat to pass array between 2 activity ^^
Hope this way can help you!