long in java example
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Android development
long is 64 bit signed type and used when int is not large enough to hold the value.
long je celé číslo 64 bitů -9223372036854775808 +9223372036854775807 a používá se tam, kde typ int není schopen pojmout takovou hodnotu čísla.
long is 64 bit signed type and used when int is not large enough to hold the value.
long je celé číslo 64 bitů -9223372036854775808 +9223372036854775807 a používá se tam, kde typ int není schopen pojmout takovou hodnotu čísla.
// declaration and assignment of value type long
long n = 22337203685477580L;
// print formated value
System.out.printf("The value of x is %d%n", n); // 22337203685477580
System.out.format("%+,8d%n%n", n); // +22 337 203 685 477 580
// declaring more variables in single statement
long lo1 = 12L, lo2 = 56, lo3 = 1455555555589L;
// long range of value
System.out.println(Long.MAX_VALUE); // 9223372036854775807
System.out.println(Long.MIN_VALUE); // -9223372036854775808
// check if a string is a valid number in Java example
// convert string to long Java example
String sLong = "1288888888888888";
long longParse = Long.parseLong(sLong);
// convert strings to numbers
long longFromString = (Long.valueOf(sLong)).longValue();
// long to string in Java example code
Long longObj = new Long(229999999999L);
String str = longObj.toString();
// else
Long longS = 888888888888L;
String strLong = longS.toString();
// compare two long variables
Long longComp1 = 5555L;
if (longComp1.equals(55555555L))
System.out.print("true");
// compares the two specified long values in Java example
int i = longS.compareTo(444444L); // -1 first < second
// 0 first == second
// 1 first > second
System.out.print(i);
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Další témata ....(Topics)
MainActivity.java
activity_main.xml
AndroidManifest.xml do not forget INTERNET uses-permission !!!!!!!
package com.asynctaskexample;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import android.os.AsyncTask;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.widget.ProgressBar;
import android.widget.TextView;
public class MainActivity extends Activity {
private TextView textView;
private ProgressBar progressBar;
private DownloadWebPageTask mTask = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textView = (TextView) findViewById(R.id.TextView01);
downloadPage();
}
// AsyncTask <TypeOfVarArgParams , ProgressValue , ResultValue> .
private class DownloadWebPageTask extends AsyncTask<String, Integer, String> {
@Override
protected void onPreExecute() {
//textView.setText("Hello !!!");
progressBar = (ProgressBar) findViewById(R.id.progressBar1);
progressBar.setVisibility(View.VISIBLE);
super.onPreExecute();
}
@Override
protected void onProgressUpdate(Integer... values) {
super.onProgressUpdate(values);
}
@Override
protected String doInBackground(String... urls) {
String response = "";
for (String url : urls) {
DefaultHttpClient client = new DefaultHttpClient();
HttpGet httpGet = new HttpGet(url);
try {
HttpResponse execute = client.execute(httpGet);
InputStream content = execute.getEntity().getContent();
BufferedReader buffer = new BufferedReader(new InputStreamReader(
content));
String s = "";
while ((s = buffer.readLine()) != null) {
response += s;
}
} catch (Exception e) {
e.printStackTrace();
}
}
return response;
}
@Override
protected void onPostExecute(String result) {
progressBar.setVisibility(View.INVISIBLE);
textView.setText(result);
}
}
private void downloadPage() {
if (mTask != null
&& mTask.getStatus() != DownloadWebPageTask.Status.FINISHED) {
mTask.cancel(true);
}
// execute(String[]) you can put array of links to web pages, or array of Integer[]
// if first param is Integer[] etc.
mTask = (DownloadWebPageTask) new DownloadWebPageTask()
.execute(new String[] { "//android.okhelp.cz/android-market.html",
"//android.okhelp.cz/android-market.html" });
}
@Override
protected void onDestroy() {
super.onDestroy();
if (mTask != null
&& mTask.getStatus() != DownloadWebPageTask.Status.FINISHED) {
mTask.cancel(true);
mTask = null;
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
}
activity_main.xml
<LinearLayout xmlns:android="//schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<ProgressBar
android:id="@+id/progressBar1"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<TextView
android:id="@+id/TextView01"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/hello_world" />
</LinearLayout>
AndroidManifest.xml do not forget INTERNET uses-permission !!!!!!!
<uses-permission android:name="android.permission.INTERNET" />
// file name MyFirstClass.java
import java.util.*;
import java.lang.Math;
import java.io.*;
import javax.swing.*;
public class MyFirstClass{ // start of program
public static void main(String[] args) { // basic function main
// variables and calculation
int a=2;
int b=3;
int c=Integer.parseInt(JOptionPane.showInputDialog(" Put number: ", "1"));
System.out.println("Number is: "+c);
System.out.println(a+" * "+b+" = "+(a*b));
System.out.println("a^3 "+Math.pow(a,b));
//array
int[] array_my=new int[10];
array_my[0]=3;
array_my[1]=5;
System.out.println("Number of elements "+array_my.length+" 1 + 2 element of array "+(array_my[0]+array_my[1]));
//strings
String txt="Quick red fox";
String txt2=JOptionPane.showInputDialog("Write text: ", "word");
System.out.println("Text is: "+txt2);
String[] count_of_word=txt.split(" ");
System.out.println("Length: "+txt.length()+" Count of words "+count_of_word.length);
System.out.println(txt +" -> "+txt.replace("red","brown"));
System.out.println("First 5 chars of string is: "+ txt.substring(0,5));
//for a if
for(int i=0; i<10;i++){
if(i==3)System.out.println("i equal "+i);
}
// file
try {
File soubor=new File("some_file.txt");
if(!soubor.exists()){
System.out.println("File dont exist");
}
else { // utf-8 encoding
BufferedReader in1 = new BufferedReader(new InputStreamReader(new FileInputStream(soubor),"UTF-8"));
BufferedWriter out1 = new BufferedWriter(new OutputStreamWriter(new FileOutputStream("zapis.txt"),"UTF-8"));
String str;
while ((str = in1.readLine())!=null){
System.out.println(str);
out1.write(str+"
");
}
in1.close();
out1.close();
}
} catch(IOException e){System.out.println("Error " + e);}
// dir
File pathName = new File("some_dir");
String[] fileNames = pathName.list();
if(pathName.exists())
System.out.println("Name of first file in "some_dir": "+fileNames[0]);
else System.out.println("dir not exist");
//function
int nResult = calculateMyFc(3,5);
System.out.println("Result of function: "+nResult);
} // end of function main
// new function , you can add to end MyFc = my function
public static int calculateMyFc(int a, int b){
return (a+b);
}
} // end of class of program
Try two way in Eclipse IDE:
1.) Import the library project into your Eclipse workspace.
Click File > Import,
select Android > Existing Android Code into Workspace, and browse to the copy of the library project to import it.
If project not visible with checkbox try next step as see below.
2.) Click
File > New > Other
select Android > Existing Android Code into Workspace, and browse to the copy of the library project to import it.
1.) Import the library project into your Eclipse workspace.
Click File > Import,
select Android > Existing Android Code into Workspace, and browse to the copy of the library project to import it.
If project not visible with checkbox try next step as see below.
2.) Click
File > New > Other
select Android > Existing Android Code into Workspace, and browse to the copy of the library project to import it.
How to quickly change all icon set in .apk project with Eclipse:
Right click on project in folder tree
Select New - Ohter
In open wizard dialog select Android Icon Set
Set Icon set name:
Open some large icon for your project for example 512x512 px and wizard will make all set of icons from one largest icon:
Wizard will create all set of icons from this one largest icon.
Click on finish button:
Right click on project in folder tree
Select New - Ohter

In open wizard dialog select Android Icon Set

Set Icon set name:

Open some large icon for your project for example 512x512 px and wizard will make all set of icons from one largest icon:

Wizard will create all set of icons from this one largest icon.
Click on finish button:

Eclipse Navigation Shortcuts.
Keyboard_shortcuts_(3.0).pdf
Ctrl+1 Quick fix problem
Ctrl+O Quick Outline
Ctrl+Shift+G Find references in workspace
Ctrl+Shift+U Find all references in file
Ctrl+Shift+T Find Java Typ
[caption id="attachment_1214" align="alignleft" width="150" caption="eclipse-ctrl-shift-t"]
[/caption]
Ctrl+Shift+R Find Resource
Ctrl+E Open Editor Drop-Down
Ctrl+Space Content Assist
Ctrl+Shift+Space Context Information
F3 Open Declaration of variable
F4 Open Type Hierarchy
Ctrl+H Open Search Dialog
Alt+Shift+R Rename - Refactoring
Alt+Shift+M Extract Method
Alt+Shift+L Extract Local Variable
Alt Shift Up Expand selection to enclosing element
Alt Shift Right Expand selection to next element
Alt Shift Left Expand selection to previous element
Alt Shift Down Restore previous selection
Breakpoints Shift+Alt+Q B
Cheat Sheets Shift+Alt+Q H
Console Shift+Alt+Q C
Java Declaration Shift+Alt+Q D
Java Package Explorer Shift+Alt+Q P
Java Type Hierarchy Shift+Alt+Q T
Javadoc Shift+Alt+Q J
Search Shift+Alt+Q S
Show View (View: Outline)Shift+Alt+Q O
Show View (View: Problems)Shift+Alt+Q X
Synchronize Shift+Alt+Q Y
Variables Shift+Alt+Q V

Keyboard_shortcuts_(3.0).pdf
Ctrl+1 Quick fix problem

Ctrl+O Quick Outline

Ctrl+Shift+G Find references in workspace
Ctrl+Shift+U Find all references in file

Ctrl+Shift+T Find Java Typ
[caption id="attachment_1214" align="alignleft" width="150" caption="eclipse-ctrl-shift-t"]

Ctrl+Shift+R Find Resource

Ctrl+E Open Editor Drop-Down
Ctrl+Space Content Assist

Ctrl+Shift+Space Context Information

F3 Open Declaration of variable
F4 Open Type Hierarchy
Ctrl+H Open Search Dialog
Alt+Shift+R Rename - Refactoring
Alt+Shift+M Extract Method
Alt+Shift+L Extract Local Variable
Alt Shift Up Expand selection to enclosing element
Alt Shift Right Expand selection to next element
Alt Shift Left Expand selection to previous element
Alt Shift Down Restore previous selection
Breakpoints Shift+Alt+Q B
Cheat Sheets Shift+Alt+Q H
Console Shift+Alt+Q C
Java Declaration Shift+Alt+Q D
Java Package Explorer Shift+Alt+Q P
Java Type Hierarchy Shift+Alt+Q T
Javadoc Shift+Alt+Q J
Search Shift+Alt+Q S
Show View (View: Outline)Shift+Alt+Q O
Show View (View: Problems)Shift+Alt+Q X
Synchronize Shift+Alt+Q Y
Variables Shift+Alt+Q V

Editace: 2011-09-26 20:49:35
Počet článků v kategorii: 396
Url:long-in-java-example
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