I have researched similar problems but none is a fit for this problem. Am trying to access the arrays of drawables from the method name called nextQuestion(), but i keep getting the error cannot resolve symbol 'ballArray' any help please. I just feel that this should work but don't know why. Here is my code.
public class MainActivity extends AppCompatActivity {
ImageView mBallDisplay;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
int quote;
mBallDisplay = (ImageView) findViewById(R.id.image_eightBall);
Button nextbutton = (Button) findViewById(R.id.nextbutton);
Button prevbutton = (Button) findViewById(R.id.prevbutton);
final int[] ballArray = {
R.drawable.ball1,
R.drawable.ball2,
R.drawable.ball3,
R.drawable.ball4,
R.drawable.ball5
};
//next button
nextbutton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
nextQuestion();
}
});
//previous button
prevbutton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
prevQuestion();
}
});
}
private void nextQuestion(){
mBallDisplay.setImageResource(ballArray[4]);
}
private void prevQuestion(){
}
}
The reason you can't access ballArray from within nextQuestion() is because it's declared in a separate method. If you want it accessible from within nextQuestion(), you would need to make it visible at that level:
ImageView mBallDisplay;
final int[] ballArray = {
R.drawable.ball1,
R.drawable.ball2,
R.drawable.ball3,
R.drawable.ball4,
R.drawable.ball5
};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
int quote;
mBallDisplay = (ImageView) findViewById(R.id.image_eightBall);
Button nextbutton = (Button) findViewById(R.id.nextbutton);
Button prevbutton = (Button) findViewById(R.id.prevbutton);
//next button
nextbutton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
nextQuestion();
}
});
//previous button
prevbutton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
prevQuestion();
}
});
}
private void nextQuestion(){
mBallDisplay.setImageResource(ballArray[4]);
}
private void prevQuestion(){
}
}
Do like this:-
public class MainActivity extends AppCompatActivity {
ImageView mBallDisplay;
int[] ballArray = {
R.drawable.ball1,
R.drawable.ball2,
R.drawable.ball3,
R.drawable.ball4,
R.drawable.ball5
};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
int quote;
mBallDisplay = (ImageView) findViewById(R.id.image_eightBall);
Button nextbutton = (Button) findViewById(R.id.nextbutton);
Button prevbutton = (Button) findViewById(R.id.prevbutton);
//next button
nextbutton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
nextQuestion();
}
});
//previous button
prevbutton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
prevQuestion();
}
});
}
private void nextQuestion(){
mBallDisplay.setImageResource(ballArray[4]);
}
private void prevQuestion(){
}
}
Related
I'm new in java and I have tried to make a food app in android studio. I have a bar in app and when I click on cart my app is crashing.
Here is my MainActivity
public class MainActivity extends AppCompatActivity {
private RecyclerView.Adapter adapter, adapter2;
private RecyclerView recyclerViewCategotyList, recyclerViewPopularList;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
recyclerViewCategoty();
recyclerViewPopular();
bottomNavigation();
}
private void bottomNavigation() {
LinearLayout homeBtn=findViewById(R.id.homeBtn);
LinearLayout cartBtn=findViewById(R.id.cartBtn);
homeBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
startActivity(new Intent(MainActivity.this,MainActivity.class));
}
});
cartBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
startActivity(new Intent(MainActivity.this,CartActivity.class));
}
});
}
And I have this error: at com.example.food.Activity.MainActivity$2.onClick(MainActivity.java:48)
This is CartActivity
public class CartActivity extends AppCompatActivity {
private RecyclerView.Adapter adapter;
private RecyclerView recyclerViewList;
private ManagementCart managementCart;
private TextView totalFeeTxt, taxTxt, deliveryTxt, totalTxt, emptyTxt;
private double tax;
private ScrollView scrollView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_cart);
managementCart = new ManagementCart(this);
initView();
initList();
bottomNavigation();
calculateCard();
}
private void bottomNavigation() {
LinearLayout homeBtn = findViewById(R.id.homeBtn);
LinearLayout cartBtn = findViewById(R.id.cartBtn);
homeBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
startActivity(new Intent(CartActivity.this, MainActivity.class));
}
});
cartBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
startActivity(new Intent(CartActivity.this, MainActivity.class));
}
});
}
I don't know what's wrong and why my setOnClickListener doesn't work.
Thank you.
I think your button R.id.homeBtn is not LinearLayout, can you show your xml file?
If your buttons are Button classes, try this
private void bottomNavigation() {
Button homeBtn = findViewById(R.id.homeBtn);
Button cartBtn = findViewById(R.id.cartBtn);
homeBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
startActivity(new Intent(CartActivity.this, MainActivity.class));
}
});
cartBtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
startActivity(new Intent(CartActivity.this, MainActivity.class));
}
});
}
The code throws compile time error:
Class 'Anonymous class derived from OnLongClickLister' is not abstract and does not override abstract method onLongClick(View) in OnLongClickListener
Code:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button amitsbutton = (Button) findViewById(R.id.amitsbutton);
amitsbutton.setOnClickListener(
new Button.OnClickListener() {
public void onClick(View v) {
TextView amitstext = (TextView) findViewById(R.id.amitstext);
amitstext.setText("Small click is working");
}
}
);
amitsbutton.setOnLongClickListener(
new Button.OnLongClickListener() {
public boolean OnLongClick(View v) {
TextView amitstext = (TextView) findViewById(R.id.amitstext);
amitstext.setText("long click is also working ");
return true;
}
}
);
You're not overriding the right method. It's onLongClick, not OnLongClick. See below:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button amitsbutton = (Button) findViewById(R.id.amitsbutton);
amitsbutton.setOnClickListener(
new Button.OnClickListener() {
public void onClick(View v) {
TextView amitstext = (TextView) findViewById(R.id.amitstext);
amitstext.setText("Small click is working");
}
}
);
amitsbutton.setOnLongClickListener(
new Button.OnLongClickListener() {
public boolean onLongClick(View v) {
TextView amitstext = (TextView) findViewById(R.id.amitstext);
amitstext.setText("long click is also working ");
return true;
}
}
);
I have a counter program for number. I define 3 buttons for Plus, Minus and Clear.
When I use clear button for clear TextView it's good. But after using Plus and Minus it it is Continuation last counter. that is my code.
please Help me.
public class CounterActivity extends Activity {
private Button btnPlus;
private Button btnMinus;
private Button btnClear;
private TextView txtCounter;
int counter = 0;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.counter_menu);
btnPlus = (Button) findViewById(R.id.btnPlus);
btnMinus = (Button) findViewById(R.id.btnMinus);
btnClear = (Button) findViewById(R.id.btnClear);
txtCounter = (TextView) findViewById(R.id.txtCounter);
btnPlus.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View view) {
counter++;
txtCounter.setText(counter + "");
}
});
btnMinus.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View view) {
counter--;
txtCounter.setText(counter + "");
}
});
btnClear.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
txtCounter.setText(0 + "");
}
});
}
}
Change your clear button onClick method as follows:
btnClear.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
counter = 0;
txtCounter.setText(0 + "");
}
});
I am having a layout file and 5 buttons -- 1 for next and 2 for previous etc. Application runs fine, when I click first button, it loads the image correctly, then as I click another button, it gives the error -Caused by java lang Out Of Memory Error
public class MainActivity extends ActionBarActivity {
private ShareActionProvider mShareActionProvider;
ImageButton btn1;
ImageButton btn2;
ImageButton btn3;
ImageButton btn4;
ImageButton btn5;
ImageButton btn6;
ImageButton btn7;
ImageButton btn8;
ImageView image1;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
addListenerOnButton();
addListenerOnButton2();
addListenerOnButton3();
addListenerOnButton4();
addListenerOnButton5();
addListenerOnButton6();
}
public void addListenerOnButton() {
btn1= (ImageButton) findViewById(R.id.btn1);
btn1.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View view)
{
setContentView(R.layout.show);
}
}
);
}
public void addListenerOnButton2() {
btn2= (ImageButton) findViewById(R.id.btn2);
btn2.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View view)
{
setContentView(R.layout.k2);
}
}
);
}
public void addListenerOnButton3() {
final Context context =this;
btn3= (ImageButton) findViewById(R.id.btn3);
btn3.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View view)
{
setContentView(R.layout.k3);
}
}
);
}
public void addListenerOnButton4() {
final Context context =this;
btn4= (ImageButton) findViewById(R.id.btn4);
btn4.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View view)
{
setContentView(R.layout.k4);
}
}
);
}
public void addListenerOnButton5() {
final Context context =this;
btn5= (ImageButton) findViewById(R.id.btn5);
btn5.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View view)
{
setContentView(R.layout.k5);
}
}
);
}
public void addListenerOnButton6() {
final Context context =this;
btn6= (ImageButton) findViewById(R.id.btn6);
btn6.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View view)
{
setContentView(R.layout.k6);
}
}
);
}
You are changing the whole layout instead of changing the image. When you do that, garbage collector is not called and you should be calling it on your own. Since it's not called, you are going to get that error pretty soon.
Do it like this instead
int[] imageArray = {R.drawable.image1, R.drawable.image2, ... };
and when you click a button, just do
btn1.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View view)
{
someImageView.setImageResource(imgageArray[0])
}
}
Also make sure you don't use too big images. The take up a lot of memory.
i have 6 layouts and each layout having two button back and next..without button back and next application runs properly but when i put code in back and next button having name button 7 is used for back and button 8 is used for next layout it gives me a error null exception.
ImageButton btn1;
ImageButton btn2;
ImageButton btn3;
ImageButton btn4;
ImageButton btn5;
ImageButton btn6;
ImageButton btn7;
ImageButton btn8;
ImageView view;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
addListenerOnButton7();
//addListenerOnButton8();
addListenerOnButton();
addListenerOnButton2();
addListenerOnButton3();
addListenerOnButton4();
addListenerOnButton5();
addListenerOnButton6();
public void addListenerOnButton7() {
btn7= (ImageButton) findViewById(R.id.btn7);
btn7.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View view)
{
setContentView(R.layout.show);
Runtime.getRuntime().gc();
}
}
);
}
public void addListenerOnButton() {
btn1= (ImageButton) findViewById(R.id.btn1);
btn1.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View view)
{
setContentView(R.layout.show);
Runtime.getRuntime().gc();
}
}
);
}
public void addListenerOnButton2() {
btn2= (ImageButton) findViewById(R.id.btn2);
btn2.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View view)
{
setContentView(R.layout.k2);
Runtime.getRuntime().gc();
}
}
);
}
public void addListenerOnButton3() {
btn3= (ImageButton) findViewById(R.id.btn3);
btn3.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View view)
{
setContentView(R.layout.k3);
Runtime.getRuntime().gc();
}
}
);
}
public void addListenerOnButton4() {
btn4= (ImageButton) findViewById(R.id.btn4);
btn4.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View view)
{
setContentView(R.layout.k4);
Runtime.getRuntime().gc();
}
}
);
}
public void addListenerOnButton5() {
btn5= (ImageButton) findViewById(R.id.btn5);
btn5.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View view)
{
setContentView(R.layout.k5);
Runtime.getRuntime().gc();
}
}
);
}
public void addListenerOnButton6() {
btn6= (ImageButton) findViewById(R.id.btn6);
btn6.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View view)
{
setContentView(R.layout.k6);
Runtime.getRuntime().gc();
}
}
);
}
You already use it in there
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
Looking at the code, it looks like it comes from inside an activity so you need to call setContentView(R.layout.activity_main); in the onCreate() of your activity before btn7= (ImageButton) findViewById(R.id.btn7); and that should fix the NullPointer.