I get a null pointer exception and the program crash on each time I want to update the highscore text using setText(). what causes this problem?
this code is when i set my layout, the layout is a part of the gameView using opengl, and I put the highscore textview on the upper left corner
public void onCreate(Bundle savedInstanceState) {
SFEngine.display = ((WindowManager)getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();//ambl ukuran width height layar
super.onCreate(savedInstanceState);
gameView = new SFGameView(this);
gameView.setLayoutParams(new RelativeLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
RelativeLayout layout = new RelativeLayout(this);
layout.setLayoutParams(new FrameLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
TextView textBox = new TextView(this);
textBox.setId(1);
textBox.setText("HIGH SCORE");
textBox.setBackgroundColor(Color.BLUE);
textBox.setWidth(SFEngine.display.getWidth()/2);
textBox.setHeight(50);
Button pauseButton = new Button(this);
pauseButton.setText("PAUSE");
pauseButton.setHeight(50);
pauseButton.setWidth(SFEngine.display.getWidth()/2);
pauseButton.setOnTouchListener(new OnTouchListener(){
public boolean onTouch(View v, MotionEvent e) {
//pause game
SFEngine.isPlaying = false;
Intent i1 = new Intent(SFGames.this, pause.class);
gameView.onPause();
startActivityForResult(i1,0);//hrs pk result soalny mw blk lg
return true;
}
});
RelativeLayout.LayoutParams lp_pause = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT);
RelativeLayout.LayoutParams lp_hs = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT);
lp_hs.addRule(RelativeLayout.ALIGN_PARENT_LEFT);
lp_pause.addRule(RelativeLayout.ALIGN_PARENT_TOP);
lp_pause.addRule(RelativeLayout.ALIGN_PARENT_RIGHT);
textBox.setLayoutParams(lp_hs);
pauseButton.setLayoutParams(lp_pause);
layout.addView(gameView);
layout.addView(textBox);
layout.addView(pauseButton);
setContentView(layout);
and here is the setText code
public boolean onTouchEvent (MotionEvent event){//buat nerima input user
if(!SFEngine.isPlaying){
finish();
}
textBox.setText("High Score :" + SFEngine.score);//here is the source of the prob
.....
error log:
10-13 22:38:34.207: E/AndroidRuntime(528): FATAL EXCEPTION: main
10-13 22:38:34.207: E/AndroidRuntime(528): java.lang.NullPointerException
10-13 22:38:34.207: E/AndroidRuntime(528): at com.starfighter.SFGames.onTouchEvent(SFGames.java:136)
10-13 22:38:34.207: E/AndroidRuntime(528): at android.app.Activity.dispatchTouchEvent(Activity.java:2367)
UPDATE :
i've updated the source code so the textview declaration is outside of the onCreate, it seems to be working normally now..
You should define the text view as a class field in the activity, outside the onCreate:
TextView textBox;
public void onCreate(Bundle savedInstanceState) {
....
textBox = new TextView(this);
}
Your textBox is a local variable in the onCreate() method. I think you have a member variable with the same name, too. So you actually using the wrong one.
Try to remove TextView in your onCreate()
// in onCreate
textBox = new TextView(this);
textBox.setId(1);
textBox.setText("HIGH SCORE");
put TextView declaration outside of the onCreate()
TextView textBox;
public void onCreate(Bundle savedInstanceState) {
textBox = (TextView)findViewById(id.TextBoxNameFromLayout);
}
Your textbox should be defined as global variable.
like this
class MyActivity extends Activity{
TextView textBox = null;
#Override
public void onCreate(Bundle savedInstanceState) {
...
textBox = new TextView(this);
Related
How can we create a button with a command to create an other object on Android ?
i mean, i press the button on the app and it create in the layout, a new object, for exemple a textView.
how could i proceed ?
thanks !
This is a way:
First you defined into your xml file a layout parent for your TextView and get it in your code:
final LinearLayout parentView = (LinearLayout) findViewById(R.id.parent_view_id);
Then you define create your TextView for example:
final TextView textView = new TextView(context);
LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(
LinearLayout.LayoutParams.WRAP_CONTENT,
LinearLayout.LayoutParams.MATCH_PARENT
); // set height and width
textView.setMargins(left, top, right, bottom); // set margin if necessary
textView.setLayoutParams(layoutParams);
and in your listener :
myButton.setOnClickListener(new View.OnClickListener() {
#Override public void onClick(View view) {
parentView.addView(textView);
}
});
Hope this helps.
Sorry for my english.
first of all create a click listener on your button
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
}
}
and then this with add a new textview into your target layout
TextView tv = new TextView(this);
tv.setText("hello word!");
tv.setTextSize(18);
tv.setTextColor(Color.BLACK);
tv.setClickable(true);
tv.setPadding(0, 10, 0, 0);
tv.setGravity(Gravity.CENTER);
mainLayout.addView(tv);
in this ex mainLayout is the view that you want to add new object like textview, ....
I want to create multiple TextViews inside a LinearLayout.The following code builds successfully but gives a NullPointerException at the line root.addView(t[i]);
public class MainActivity extends ActionBarActivity {
TextView t[];
LinearLayout root;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
root=(LinearLayout)findViewById(R.id.master);
t=new TextView[10];
LinearLayout.LayoutParams dim=new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);
for(int i=0;i<10;i++)
{
t[i]=new TextView(this);
t[i].setLayoutParams(dim);
t[i].setText("YOHOHO: "+i);
root.addView(t[i]);
}
setContentView(root);
}
This really has no aim Iam just trying to learn things!
It's giving NPE because you are not setting your activity layout properly.
Do this
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.whereLinearLayoutMasterIs); // Add your layout here
root=(LinearLayout)findViewById(R.id.master);
t=new TextView[10];
LinearLayout.LayoutParams dim=new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);
for(int i=0;i<10;i++)
{
t[i]=new TextView(this);
t[i].setLayoutParams(dim);
t[i].setText("YOHOHO: "+i);
root.addView(t[i]);
}
}
NOTER.layout.whereLinearLayoutMasterIs is indicative, use your layout in which R.id.master is
The problem is that root is null - this is because you've not yet set your Activity's content view via setContentView.
You need to do something like this:
super.onCreate(...);
setContentView(R.layout.yourLayoutName);
root=(LinearLayout)findViewById(R.id.master);
I have an Android application in which i send data from one activity to another. I can do that part easily but the problem is i want to display some additional TextViews as well. So when i display the sent data using setContentView i can see only the sent data. I cannot see the additional TextViews. I want both of them to be displayed simultaneously.
I searched and tried hard to find a solution without any luck.I am attaching the code for reference.Thanks!
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_crop_information);
Intent intent = getIntent();
String message = intent.getStringExtra(CropsListActivity.EXTRA_MESSAGE);
TextView textViewci= new TextView(this);
textViewci.setText(message);
TextView textView1= new TextView(this);
TextView textView2= new TextView(this);
textView1.setText("Major Districts");
textView2.setText("Suitable Soil");
When i use this code,i am unable to see anything and the activity remains blank.Actually i am using a TableLayout here so that i can display data in form of tables
You have to add text view on your layout.
View linearLayout = findViewById(R.id.info);
//LinearLayout layout = (LinearLayout) findViewById(R.id.info);
TextView valueTV = new TextView(this);
valueTV.setText("hallo hallo");
valueTV.setId(5);
valueTV.setLayoutParams(new LayoutParams(
LayoutParams.FILL_PARENT,
LayoutParams.WRAP_CONTENT));
((LinearLayout) linearLayout).addView(valueTV);
You have to add the text view in the parentview. For example, if you have used the text view in the linear layout then add the text view in the linear layout and then use the addview(linearlayout).
Below is the example
RelativeLayout layout = new RelativeLayout(this);
TextView tv1 = new TextView(this);
tv1.setText("A");
tv1.setId(23);
TextView tv2 = new TextView(this);
tv2.setText("B");
RelativeLayout.LayoutParams lp = new RelativeLayout.LayoutParams(
RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.FILL_PARENT);
lp.addRule(RelativeLayout.RIGHT_OF, tv1.getId());
layout.addView(tv1);
layout.addView(tv2, lp);
I have just make a test program for you. first class code
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button = (Button) findViewById(R.id.button1);
button.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
Intent intent = new Intent(MainActivity.this, SecondClass.class);
intent.putExtra("firstValue", "1");
intent.putExtra("secondValue", "2");
startActivity(intent);
}
});
Second class code :
setContentView(R.layout.activity_crop_information);
Intent intent = getIntent();
String message1 = intent.getStringExtra("firstValue");
String message2 = intent.getStringExtra("secondValue");
RelativeLayout layout = new RelativeLayout(this);
TextView textView1= new TextView(this);
TextView textView2= new TextView(this);
TextView textViewci= new TextView(this);
textViewci.setText(message1+""+message2);
Log.e("intent value is", ""+message1+""+message2);
RelativeLayout.LayoutParams lp = new RelativeLayout.LayoutParams(
RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.FILL_PARENT);
lp.addRule(RelativeLayout.RIGHT_OF, textView1.getId());
textView1.setText("Major Districts");
textView2.setText("Suitable Soil");
layout.addView(textView1);
layout.addView(textView2);
addContentView(layout, lp);
Try and let me know. YOu have to make related layouts for both classes.
Hope this will help
are you getting any error messages? if yes then please post them here. and the others are right.you need to add yours views to the parent layout.
I have found out the answer by myself.It's fairly easy and there is no need here to use views in the parent layout.I modified the textViews in my xml file and got their values using findViewById.I am attaching the updated code.
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_crop_information);
Intent intent = getIntent();
String message = intent.getStringExtra(CropsListActivity.EXTRA_MESSAGE);
textView=(TextView)findViewById(R.id.textViewci);
textView1=(TextView)findViewById(R.id.textViewmd);
textView2=(TextView)findViewById(R.id.textViewso);
textView.setText(message);
textView1.setText("Major Districts");
textView2.setText("Suitable Soil");
tf = Typeface.createFromAsset(getAssets(), "fonts/SHRUTIB.TTF");
textView.setTypeface(tf);
}
Well I am trying to see if a checkbox is checked or not, but I get errors.
Defining the checkbox code:
public class Preferences extends PreferenceActivity {
CheckBoxPreference togglePref;
...
}
CheckBox Code:
public void checkNotify() {
if (togglePref.isChecked()==(true)) {
...
}
}
OnCreate code:
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//SharedPreferences settings = getSharedPreferences("EasySettingsPreferences", MODE_PRIVATE);
//boolean notify = settings.getBoolean("notify", false);
checkNotify();
rootView = new LinearLayout(this);
rootView.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
rootView.setOrientation(LinearLayout.VERTICAL);
togglePref = new CheckBoxPreference(this);
textView = new TextView(this);
textView.setText(R.string.app_name);
titleView = new LinearLayout(this);
titleView.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, 26));
titleView.setBackgroundResource(R.drawable.pattern_carbon_fiber_dark);
titleView.addView(textView);
preferenceView = new ListView(this);
preferenceView.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
preferenceView.setId(android.R.id.list);
PreferenceScreen screen = createPreferenceHierarchy();
screen.bind(preferenceView);
preferenceView.setAdapter(screen.getRootAdapter());
rootView.addView(titleView);
rootView.addView(preferenceView);
this.setContentView(rootView);
setPreferenceScreen(screen);
}
Logcat Picture:
logcat pic http://img710.imageshack.us/img710/8529/unledxq.png
Debugger Picture
debugger pic http://img847.imageshack.us/img847/1192/unled1rn.png
Please help me if you can. Thanks!
I guess that you never initialise togglePref. To be sure we need to see the onCreate(). (I will update my answer if my guess was wrong...)
edit
I was right. You call checkNotify() before your even initialized the togglePref variable. Check your logic if it really makes sense to call that method before everything else or if it is fine if you call it later.
A tip: You can simplify your if statement:
// yours:
if (togglePref.isChecked()==(true)) {
// simplified:
if (togglePref.isChecked()) {
In your onCreate() method, you're calling checkNotify() before togglePref has been initialized. You want to move that initialization up (or move checkNotify() down.)
I'm having trouble adding a button to a layout that I've created in XML. Here's what I want to achieve:
//some class
else {
startActivity(new Intent(StatisticsScreen.this, ScreenTemperature.class));
}
////
//ScreenTemperatureClass
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//this is where I call another class that
//displays a nice graph
setContentView(new GraphTemperature(getApplicationContext()));
}
I want to add a Button to this new screen so that it'll appear below the graph.
I've tried creating a LinearLayout view, then create a Button and add it to this view but I just get NullPointerExceptions..
Any help would be appreciated. Thanks
EDIT#1
Here's what I've tried using that created a NullPointerException and 'force close':
Button buybutton;
LinearLayout layout;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new GraphTemperature(getApplicationContext()));
layout = (LinearLayout) findViewById(R.id.statsviewlayout);
Button buyButton = new Button(this);
buyButton.setText(R.string.button_back);
buyButton.setLayoutParams(new LayoutParams(
ViewGroup.LayoutParams.WRAP_CONTENT,
ViewGroup.LayoutParams.WRAP_CONTENT));
layout.addView(buyButton);
}
And here's the logcat error:
ERROR/AndroidRuntime(293): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.weatherapp/com.weatherapp.ScreenTemperature}: java.lang.NullPointerException
ERROR/AndroidRuntime(293): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
ERROR/AndroidRuntime(293): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
ERROR/AndroidRuntime(293): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
ERROR/AndroidRuntime(293): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
theres abviously more lines to do with this error in logcat, not sure if you want it?
EDIT#2
So i tried bhups method:
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
GraphTemperature GT = new GraphTemperature(getApplicationContext());
layout = (LinearLayout) findViewById(R.id.statsviewlayout);
Button buyButton = new Button(this);
buyButton.setText(R.string.button_back);
buyButton.setLayoutParams(new LayoutParams(
ViewGroup.LayoutParams.WRAP_CONTENT,
ViewGroup.LayoutParams.WRAP_CONTENT));
layout.addView(GT); // line 27
layout.addView(buyButton);
setContentView(layout);
}
This method produced the same logcat error as above, NullPointerException, indicating it was something to do with line no. 27 which is the layout.addView line of code. Any ideas? Thanks again
If you just have included a layout file at the beginning of onCreate() inside setContentView and want to get this layout to add new elements programmatically try this:
ViewGroup linearLayout = (ViewGroup) findViewById(R.id.linearLayoutID);
then you can create a new Button for example and just add it:
Button bt = new Button(this);
bt.setText("A Button");
bt.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT,
LayoutParams.WRAP_CONTENT));
linerLayout.addView(bt);
This line:
layout = (LinearLayout) findViewById(R.id.statsviewlayout);
Looks for the "statsviewlayout" id in your current 'contentview'. Now you've set that here:
setContentView(new GraphTemperature(getApplicationContext()));
And i'm guessing that new "graphTemperature" does not set anything with that id.
It's a common mistake to think you can just find any view with findViewById. You can only find a view that is in the XML (or appointed by code and given an id).
The nullpointer will be thrown because the layout you're looking for isn't found, so
layout.addView(buyButton);
Throws that exception.
addition:
Now if you want to get that view from an XML, you should use an inflater:
layout = (LinearLayout) View.inflate(this, R.layout.yourXMLYouWantToLoad, null);
assuming that you have your linearlayout in a file called "yourXMLYouWantToLoad.xml"