Methods of class String

Method : charAt()

package com.test.test1;

public class StringMethods {
	public static void main(String[] args) {
		String name = new String("Paul");
		System.out.println(name.charAt(0));
		System.out.println(name.charAt(2));
	}
}

Method : indexOf()

package com.test.test1;

public class StringMethods {
	public static void main(String[] args) {
		String name = new String("ABCAB");
		System.out.println(name.indexOf('B'));
		System.out.println(name.indexOf("S"));
		System.out.println(name.indexOf("CA"));
		System.out.println(name.indexOf("B", 2));
	}
}

Method : substring()

package com.test.test1;

public class StringMethods {
	public static void main(String[] args) {
		String exam = "Oracle";
		String sub = exam.substring(2);
		String result = exam.substring(2, 4);
		System.out.println(sub);
		System.out.println(result);
	}
}

Method : trim()

package com.test.test1;

public class StringMethods {
	public static void main(String[] args) {
		String varWithSpaces = "  AB CB   ";
		System.out.print(":");
		System.out.print(varWithSpaces);
		System.out.println(":");
		System.out.println("---after trim---");
		System.out.println(varWithSpaces.trim());
	}
}

Note: trim() will not remove space with in a string.

Method : replace()

package com.test.test1;

public class StringMethods {
	public static void main(String[] args) {
		String letters = "ABCAB";
		System.out.println(letters.replace('B', 'b'));
		System.out.println(letters.replace("CA", "12"));
		System.out.println(letters);
	}
}

Output:
AbCAb
AB12B
ABCAB

Method : length()

package com.test.test1;

public class StringMethods {
	public static void main(String[] args) {
		String letters = "ABCAB";
		System.out.println(letters.length());
	}
}

length of a string is always = lastIndex+1

Methods : startsWith() and endsWith()

package com.test.test1;

public class StringMethods {
	public static void main(String[] args) {
		String letters = "ABCAB";
		System.out.println(letters.startsWith("AB"));
		System.out.println(letters.startsWith("a"));
		System.out.println(letters.startsWith("A", 3));

		System.out.println(letters.endsWith("CAB"));
		System.out.println(letters.endsWith("B"));
		System.out.println(letters.endsWith("b"));
	}
}

Method Chaining

package com.test.test1;

public class StringMethods {
	public static void main(String[] args) {
		String result = "Sunday  ".replace(' ', 'Z').trim().concat("M n");
		System.out.println(result);
	}
}

package com.test.test1;

public class StringMethods {
	public static void main(String[] args) {
		String day = "SunDday";
		day.replace('D', 'Z').substring(3);
		System.out.println(day);
		day = day.replace('D', 'Z').substring(3);
		System.out.println(day);
	}
}