Java Basic Rules
// 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
396LW NO topic_id
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Další témata ....(Topics)
Bitmap Width, Height without memory allocation:
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeResource(getResources(), R.id.myimage, options);
// now opts.outWidth and opts.outHeight are the dimension of the
// bitmap, even though Bitmap is null
int imageHeight = options.outHeight;
int imageWidth = options.outWidth;
String imageType = options.outMimeType;
Full Screen without titlebar and statusbar for Android Activity.
In Activity.java
or in AndroidManifest.xml
In Activity.java
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.main);
}
or in AndroidManifest.xml
<activity android:name=".ActivityName"
android:label="@string/app_name"
android:theme="@android:style/Theme.NoTitleBar.Fullscreen">
</activity>
Converting to string: TypedValue{t=0x10/d=0xe a=-1}
- 14
// error
- "18"
// ok
The Labeled continue statement as goto Java example.
public class MainClass {
public static void main(String[] arg) {
String[] arrayOfString = { "Hello", "people", "hello", "world!" };
OuterLoop: for (int e = 0; e < 4; e++) {
for (int i = 0; i < arrayOfString.length; i++) {
if (arrayOfString[i].equals("hello"))
continue OuterLoop;
System.out.println(arrayOfString[i]);
}
}
}
}
/*
Hello
people
Hello
people
Hello
people
Hello
people
*/
break statement in Java Android basic example
MainClass.java
MainClass.java
public class MainClass {
public static void main(String[] arg) {
String[] arrayOfString = {"nothing", "Hello", "people"
, "bye-bye", "hello", "world!", "end" };
for (int i = 0; i < arrayOfString.length; i++) {
System.out.println(arrayOfString[i]);
if(i > 2)
break; // end of loop
}
}
}
/*
nothing
Hello
people
bye-bye
*/
Editace: 2013-12-09 11:06:19
Počet článků v kategorii: 396
Url:java-basic-rules