18 – Java Predefined Methods Part-2

Selenium Class 18 – Java Predefined Methods Part-2

Categories of Predefined Methods

i) String Methods
ii) Number Methods
iii) Character Methods
iv) Array Methods
etc…

iii) Character Methods

1) isLetter () Method

It checks if a value is Alphabet or not? And returns boolean result

Example:
char a=’Z’;
char b=’1′;

System.out.println(Character.isLetter(a));//true
System.out.println(Character.isLetter(b));//false
System.out.println(Character.isLetter(‘B’));//true
System.out.println(Character.isLetter(‘2’));//false
System.out.println(Character.isLetter(‘*’));//false

2) isDigit()

It checks if a Value is number or not?

Example:
char a=’Z’;
char b=’1′;

System.out.println(Character.isDigit(a));//false
System.out.println(Character.isDigit(b));//true
System.out.println(Character.isDigit(‘4’));//true
System.out.println(Character.isDigit(‘C’));//false
System.out.println(Character.isDigit(‘%’));//false

3) isLowerCase()

It checks if a value is Lower case or not? and returns boolean result

Example:

char a=’Z’;
char b=’a’;
char c=’1′;

System.out.println(Character.isLowerCase(a));//false
System.out.println(Character.isLowerCase(b));//true
System.out.println(Character.isLowerCase(a));//false
System.out.println(Character.isLowerCase(‘s’));//true
System.out.println(Character.isLowerCase(‘Z’));//false
System.out.println(Character.isLowerCase(‘4’));//false

4) isUpperCase

It checks if a value is upper case value or not?

char a=’Z’;
char b=’a’;
char c=’1′;
System.out.println(Character.isUpperCase(a));//true
System.out.println(Character.isUpperCase(b));//false
System.out.println(Character.isUpperCase(c));//false
System.out.println(Character.isUpperCase(‘s’));//false
System.out.println(Character.isUpperCase(‘Z’));//true
System.out.println(Character.isUpperCase(‘4’));//false

iv) Array Methods

1) length()

It returns length of an Array

Example:
int [] a= {10, 20, 30, 40, 50};
System.out.println(a.length);//5

2) Copy an Array to a String

int [] a= {10, 20, 30, 40, 50};
String str= Arrays.toString(a);
System.out.println(str);

String [] a = {“UFT”, “Selenium”, “RFT”, “SilkTest”};
String str = Arrays.toString(a);
System.out.println(str);

3) Print Array using for loop
public static void main(String[] args) {
String [] a = {“UFT”, “Selenium”, “RFT”, “SilkTest”, “LoadRunner”};

for (int i=0; i<=a.length-1; i++){
System.out.println(a[i]);

4) Print Array using enhanced for loop
String [] a = {“UFT”, “Selenium”, “RFT”, “SilkTest”, “LoadRunner”};

for (String val: a){
System.out.println(val);
}

5) Check if an Array contains certain value or not?
String [] a = {“UFT”, “Selenium”, “RFT”, “SilkTest”, “LoadRunner”};

boolean val = Arrays.asList(a).contains(“UFT”);
boolean val2 = Arrays.asList(a).contains(“Java”);
System.out.println(val);//true
System.out.println(val2);//false

Java ArrayList

Java Array is Static Data Structure and ArrayList is Dynamic Data Structure

Array versus ArrayList in Java

Array is Static (its size is fixed), ArrayList is Dynamic….

Java Array Example:
int [] a= new a[4];
a[0]=10;
a[1]=20;
a[2]=30;
a[3]=40;
a[4]=50; //Error

• ArrayList is Dynamic and you can add or remove elements….

Note: ArrayList is predefined class that we have to import from java.util package

Example:

1) Create Integer type ArrayList and conduct operations

ArrayList abc = new ArrayList<>();

//Add Elements to ArrayList
abc.add(100);
abc.add(200);
abc.add(300);

//print an ArrayList Element
int a= abc.get(1);
System.out.println(a);//200

//Or
System.out.println(abc.get(1));//200

//Return Size of ArrayList
int size = abc.size();
System.out.println(size);//3

//Remove an Element from Arraylist
abc.remove(1);

System.out.println(abc.size());//2
System.out.println(abc.get(1));//

//Check the Existence of Elements
System.out.println(abc.contains(100));//true
System.out.println(abc.contains(200));//false

abc.clear();
System.out.println(abc.size());//0
abc.add(200);
abc.add(100);
System.out.println(abc.get(1));

2) Create String Type Array

ArrayList abc = new ArrayList<>();

abc.add(“Selenium”);
abc.add(“UFT”);
abc.add(“RFT”);
String a= abc.get(2);
System.out.println(a);//RFT

3) Create Character type ArrayList

ArrayList xyz = new ArrayList<>();

xyz.add(‘A‘);

System.out.println(xyz.get(0));//A

Java Data Type Conversion

To conduct Mathematical Operations sometimes we need to convert the data

1) Integer type to byte type

int a=10;
byte b=20;

System.out.println(a+b);//30
int c=a+b;
System.out.println(c);//30

byte d= (byte)(a+b);
System.out.println(d);//30

Note: If you want convert byte to integer then no conversion is required, want to convert integer to byte then data conversion is required

byte a=10;
int b=a;

int c=20;
byte d=(byte)c;
System.out.println(d);

String to Integer

Note: Whenever we read data (from files or application objects) then computer program considers the data as String type data, in order to conduct mathematical operations then we need to convert the data

*We can’t convert alphabets to numbers

1) String to Number (Integer)
String a=”10″;
String b=”20″;

System.out.println(a+b);//1020
int num1 = Integer.parseInt(a);
int num2= Integer.parseInt(b);
System.out.println(num1+num2);//30

System.out.println(Integer.parseInt(a) + Integer.parseInt(b));//30
String c=”abcd”;
System.out.println(Integer.parseInt(c));//Run-time error

2) String to Number (Number with decimal places)

String a=”10.2345″;
double val = Double.parseDouble(a);//10.2345
//int val3 = Integer.parseInt(a);

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