How to save the state of Activity - Android
onSaveInstanceState, onRestoreInstanceState , save preferences
int mCurrentPhotoIndex = 0;
@Override
protected void onSaveInstanceState(Bundle outState) {
outState.putInt("photo_index", mCurrentPhotoIndex);
super.onSaveInstanceState(outState);
}
@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
mCurrentPhotoIndex = savedInstanceState.getInt("photo_index");
super.onRestoreInstanceState(savedInstanceState);
}
// or save preferences for new start of Activity in onStop
//onCreate or onResume or onStart etc.
public void loadPreferences() {
SharedPreferences settings = getSharedPreferences(F.PREFERENCES_NAME, 0);
mCurrentPhotoIndex = settings.getInt("mCurrentPhotoIndex",mCurrentPhotoIndex);
// String_sOtazka = settings.getString("_sOtazka", _sOtazka);
}
// onStop
public void savePreferences() {
SharedPreferences settings = getSharedPreferences(PREFERENCES_NAME, 0);
SharedPreferences.Editor editor = settings.edit();
editor.putInt("mCurrentPhotoIndex", mCurrentPhotoIndex);
// String, boolean, float ...
// editor.putString("mButton1", mButton1.getText().toString());
editor.commit();
}
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Example source code for Android Developers
// clickable TextView
public TextView createTextView(String sText, Context con){
TextView b = null;
try {
b = new TextView (con);
b.setTextSize(15.0f);
b.setTextColor(Color.rgb( 0, 0, 200));
b.setOnClickListener(this);
b.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT,
LayoutParams.WRAP_CONTENT));
b.setText(sText);
//tr.addView(b, 60,30);
} catch (Exception e) {
e.printStackTrace();
return b;
}
return b;
}
/*****************/
public void onClick(View view) {
try {
String s = ((TextView) view).getText().toString();
}
catch (Exception e1) {
e1.printStackTrace();
}
}
/***********/
// if you want restore in TextView after chagne of orientation
// you have to put code to Manifest.xml android:configChanges
activity android:name=".main"
android:label="@string/app_name"
android:configChanges="keyboardHidden|orientation" //this line important !!!!!!!
File -> Settings -> Keymap you can do select Eclipse keymap from drop down menu
Ctrl+Shift+A (Help | Find Action on the main menu) and start typing the name of the action. Choose the desired action from the suggestion list.
Ctrl+Click (on Windows) or Cmd+Click (on MacOS) a tab in the editor to navigate to any part of the file path. Select the necessary element in the drop-down, and the corresponding file path opens in an external browser (e.g., in the Explorer, if your OS is Windows).
Ctrl+F find
Refactor | Rename: Shift+F6 ( +F6)
Find and replace: CTRL + R
Go to variable declaration: CTRL + B
Ctrl+Shift+I (View | Quick Definition)
Ctrl+Alt+F7 (Edit | Find | Show Usages in the main menu)
Ctrl+Shift+F find in project
Ctrl+Shift+F7 (Edit | Find | Highlight Usages in File) to quickly highlight usages of some variable in the current file.
Use F3 and Shift+F3 keys to navigate through highlighted usages.
Press Escape to remove highlighting.
Ctrl+W (extend selection) in the editor selects the word at the caret and then selects expanding areas of the source code. For example, it may select a method name, then the expression that calls this method, then the whole statement, then the containing block, etc. You can also select the word at the caret and the expanding areas of the source code by double-clicking the target areas in the editor.
To search through the classes, files, tool windows, actions, settings, and symbols of your project by double pressing the Shift key
Ctrl+P (View | Parameter Info) e.g. localURL = new URL(localUrlString); select localUrlString and press Ctrl + P
Show html documentation tooltips: CTRL + Q
Comment uncomment single line: CTRL + /
Comment uncomment selected text: CTRL + SHIFT + /
Code completion (Ctrl+Space)
Alt key and mouse pointer dragging for column selection
If nothing is selected in the editor, and you press Ctrl+C, then the whole line at caret is copied to the clipboard.
Ctrl + Delete delete word from caret to end.
Ctrl + Backspace delete word from caret to start.
Duplicate line: CTRL + D
To compare two directories,or jar files, select one or both of them in the Project view and press Ctrl+D.
Editor Delete Line: CTRL + Y
Move line UP, DOWN. Select a code fragment and press Ctrl+Shift+Up or Ctrl+Shift+Down.
To open any class or file in the editor at the desired line, press Ctrl+Shift+N (Navigate | File), start typing the name, and choose the one from the suggestion list. Then type the colon (:) and a line number
Ctrl+Shift+Enter to complete a current statement such as if, do-while, try-catch, return (or a method call)
Alt+Enter to invoke a quick fix or intention action, press the right arrow key to reveal the list of additional options.
To quickly review your recent changes to the project: Alt+Shift+C
Code Completion, you can accept the currently highlighted selection in the popup list with the period character (.), comma (,), semicolon (;), space and other characters.
Quickly move between methods in the editor: Alt+Up and Alt+Down
Ctrl+Shift+J shortcut joins two lines into one and removes unnecessary space to match your code style
Ctrl+Shift+V to choose and insert recent clipboard contents into the text
Inheritance hierarchy for a selected class: Ctrl+H
Right-clicking on a breakpoint marker you can quickly enable/disable the breakpoint or adjust its properties.
Evaluate the value of any expression while debugging the program, select its text in the editor (you may press a Ctrl+W a few times to efficiently perform this operation) and press Alt+F8.
Quickly evaluate the value of any expression while debugging the program, hold Alt and click this expression to see its value and calculate it, call a method, etc.
You can use the Extract Variable refactoring even on incomplete statements. Just select the necessary block in the editor and press Ctrl+Alt+V.
To open any particular method or field in editor: Ctrl+Alt+Shift+N
Add unimplemented methods: CTRL + I
Override methods: CTRL + O
Format code: CTRL + ALT + L
Show project: ALT + 1
Show logcat: ALT + 6
Hide project - logcat: SHIFT + ESC
Build: CTRL + F9
Build and Run: CTRL + F10
Alt+Shift+F10 access the Run/Debug dropdown on the main toolbar
Collapse all: CTRL + SHIFT + NumPad +
Expand all: CTRL + SHIFT + NumPad -
Ctrl+Shift+A (Help | Find Action on the main menu) and start typing the name of the action. Choose the desired action from the suggestion list.
Ctrl+Click (on Windows) or Cmd+Click (on MacOS) a tab in the editor to navigate to any part of the file path. Select the necessary element in the drop-down, and the corresponding file path opens in an external browser (e.g., in the Explorer, if your OS is Windows).
Find - Rename
Ctrl+F find
Refactor | Rename: Shift+F6 ( +F6)
Find and replace: CTRL + R
Go to variable declaration: CTRL + B
Ctrl+Shift+I (View | Quick Definition)
Ctrl+Alt+F7 (Edit | Find | Show Usages in the main menu)
Ctrl+Shift+F find in project
Ctrl+Shift+F7 (Edit | Find | Highlight Usages in File) to quickly highlight usages of some variable in the current file.
Use F3 and Shift+F3 keys to navigate through highlighted usages.
Press Escape to remove highlighting.
Ctrl+W (extend selection) in the editor selects the word at the caret and then selects expanding areas of the source code. For example, it may select a method name, then the expression that calls this method, then the whole statement, then the containing block, etc. You can also select the word at the caret and the expanding areas of the source code by double-clicking the target areas in the editor.
To search through the classes, files, tool windows, actions, settings, and symbols of your project by double pressing the Shift key
Ctrl+P (View | Parameter Info) e.g. localURL = new URL(localUrlString); select localUrlString and press Ctrl + P
Show html documentation tooltips: CTRL + Q
Edit
Comment uncomment single line: CTRL + /
Comment uncomment selected text: CTRL + SHIFT + /
Code completion (Ctrl+Space)
Alt key and mouse pointer dragging for column selection
If nothing is selected in the editor, and you press Ctrl+C, then the whole line at caret is copied to the clipboard.
Ctrl + Delete delete word from caret to end.
Ctrl + Backspace delete word from caret to start.
Duplicate line: CTRL + D
To compare two directories,or jar files, select one or both of them in the Project view and press Ctrl+D.
Editor Delete Line: CTRL + Y
Move line UP, DOWN. Select a code fragment and press Ctrl+Shift+Up or Ctrl+Shift+Down.
To open any class or file in the editor at the desired line, press Ctrl+Shift+N (Navigate | File), start typing the name, and choose the one from the suggestion list. Then type the colon (:) and a line number
Ctrl+Shift+Enter to complete a current statement such as if, do-while, try-catch, return (or a method call)
Alt+Enter to invoke a quick fix or intention action, press the right arrow key to reveal the list of additional options.
To quickly review your recent changes to the project: Alt+Shift+C
Code Completion, you can accept the currently highlighted selection in the popup list with the period character (.), comma (,), semicolon (;), space and other characters.
Quickly move between methods in the editor: Alt+Up and Alt+Down
Ctrl+Shift+J shortcut joins two lines into one and removes unnecessary space to match your code style
Ctrl+Shift+V to choose and insert recent clipboard contents into the text
Inheritance hierarchy for a selected class: Ctrl+H
Right-clicking on a breakpoint marker you can quickly enable/disable the breakpoint or adjust its properties.
Evaluate the value of any expression while debugging the program, select its text in the editor (you may press a Ctrl+W a few times to efficiently perform this operation) and press Alt+F8.
Quickly evaluate the value of any expression while debugging the program, hold Alt and click this expression to see its value and calculate it, call a method, etc.
You can use the Extract Variable refactoring even on incomplete statements. Just select the necessary block in the editor and press Ctrl+Alt+V.
To open any particular method or field in editor: Ctrl+Alt+Shift+N
Add unimplemented methods: CTRL + I
Override methods: CTRL + O
Format code: CTRL + ALT + L
Show project: ALT + 1
Show logcat: ALT + 6
Hide project - logcat: SHIFT + ESC
Build: CTRL + F9
Build and Run: CTRL + F10
Alt+Shift+F10 access the Run/Debug dropdown on the main toolbar
Collapse all: CTRL + SHIFT + NumPad +
Expand all: CTRL + SHIFT + NumPad -
Dialog Yes No sample code
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setMessage("Are you sure you want to exit application?")
.setCancelable(false)
.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
MyActivity.this.finish(); //Close this Activity for example: MyActivity.java
}
})
.setNegativeButton("No", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
// some code if you want
dialog.cancel();
}
});
AlertDialog alert = builder.create();
alert.show();
Java double is 64 bit double precision type used when fractional
precision calculation is required.
Java double je datový typ (reálné číslo) o velikosti 64 bitů. Používá se například pro přesný výsledek po dělení za desetinnou tečkou. Pokud nepotřebuje tak veliké číslo použijte raději typ float, šetříte tím paměť mobilního telefonu.
precision calculation is required.
Java double je datový typ (reálné číslo) o velikosti 64 bitů. Používá se například pro přesný výsledek po dělení za desetinnou tečkou. Pokud nepotřebuje tak veliké číslo použijte raději typ float, šetříte tím paměť mobilního telefonu.
// declaration and assignment of value type double
double x = 18.41785;
//print formated value
System.out.printf("The value of x is %.3f%n", x); // 18.418
// declaring more variables in single statement
double d1 = 12.4, d2 = 564.5, d3 = 14.589;
// double range of value
System.out.println(Double.MIN_VALUE); // 4.9E-324
System.out.println(Double.MAX_VALUE); // 1.7976931348623157E308
// is NaN Not-a-Number
double f = (double) Math.sqrt(-15);
boolean bNaN = Double.isNaN(f);
System.out.print(bNaN); // true
// check if a string is a valid number in Java example
// convert string to double Java example
String sD = "12.8";
double dParse = Double.parseDouble(sD);
// convert strings to numbers
String sDl = "15.48";
double dFromString = (Double.valueOf(sDl)).doubleValue();
// format double, float or long value to string
DecimalFormat formatter = new DecimalFormat(".##");
String s = formatter.format(-.5678); // -0.57
// .### -0.568
// .#### -0.5678
// .000000 -.567800
// -123.456
// .## -123.46
// #.## -123.46
// #E0 -.1E3
// ##E0 -1.2E2
//###E0 -123E0
// double to string in Java example code
Double dObj = new Double(68.5);
String str = dObj.toString();
// else
Double dS = 11.6;
String sdouble = dS.toString();
// compare two double variables
Double dComp1 = 4.3;
if(dComp1.equals(4.3))
System.out.print("true");
// compares the two specified double values in Java example
// int i = compare(double d1, double d2);
int i = Double.compare(11.5, 11.7); // -1 first < second
// 0 first == second
// 1 first > second
System.out.print(i);
5. Fragments Tutorial Ipsum.java – Czech language
Dil 5. Ipsum.java
V 1. dílu jsme se něco dozvěděli od XML souborech a typu procesoru pro správný běh Android Studia a emulátoru různých typů zařizení s Androidem.
V 2. dílu jsme rozebrali MainActivity.java
V 3. dílu jsme se zabývali HeadlinesFragment.java
V 4. dílu jsme se podívali na ArticleFragment.java
V tomto dílu je na řadě Ipsum.java soubor.
Používáme příklad i zip porojekt z https://developer.android.com/training/basics/fragments/creating.html
Pozorně si jej nastudujte.
Dil 5. Ipsum.java
V 1. dílu jsme se něco dozvěděli od XML souborech a typu procesoru pro správný běh Android Studia a emulátoru různých typů zařizení s Androidem.
V 2. dílu jsme rozebrali MainActivity.java
V 3. dílu jsme se zabývali HeadlinesFragment.java
V 4. dílu jsme se podívali na ArticleFragment.java
V tomto dílu je na řadě Ipsum.java soubor.
Používáme příklad i zip porojekt z https://developer.android.com/training/basics/fragments/creating.html
Pozorně si jej nastudujte.
package com.example.android.fragments;
/** Ipsum je veřejná třída, která obsahuje
dvě pole řetězců - stringů.
Pole Headlines slouží jako uložiště pro názvy, které
budou načteny do ListView - seznamu v HeadlinesFragment.java
Pole Articles je v našem případě zásobárnou článků, které
budou načteny dle pozice položky ListView předané z HeadlinesFragment
zoětbě do MainActivity a
odtud do ArticleFragment.java, jako parametr metody
articleFrag.updateArticleView(position);
nebo jako argument Bundle
Bundle args = new Bundle();
args.putInt(ArticleFragment.ARG_POSITION, position);
Stringy - ukládat do souboru java je ošemetné (problémy s kódováním, vyhledávání výrazů atd.)
U většího množství článků pak nepřehledné.
Navíc, uživatel nemůže tento text editovat.
K ukládaní většího množství dat, k jejich vyhledávání
a editaci je lépe používat databáze.
*/
public class Ipsum {
static String[] Headlines = {
"Article One",
"Article Two"
};
static String[] Articles = {
"Article One
Excepteur pour-over occaecat squid biodiesel umami ... farm-to-table.",
"Article Two
Vinyl williamsburg non ... synth, vegan carles odd future."
};
}
Editace: 2012-08-05 13:08:49
Počet článků v kategorii: 396
Url:how-to-save-the-state-of-activity-android