GeezerVison

package String; public class StringExamples { public static void main(String[] args) { // Strings are immutable String str3 = "value1"; str3.concat("value2"); System.out.println(str3); // value1 // The result should be assigned to a new reference variable (or same // variable) can be reused. String concat = str3.concat("value2"); System.out.println(concat); // value1value2 // A String value once created, cannot be changed. // If a method is invoked on string object, it returns a new object and // will not modify the original object. // All strings literals are stored in "String constant pool". // If compiler finds a String literal,it checks if it exists in the // pool. // If it exists, it is reused. // 1 string object (created on the pool) and 1 reference variable //String str1 = "value"; // However, if new operator is used to create string object, // the new object is created on the heap // Following piece of code create 2 objects // 1. String Literal "value" - created in the "String constant pool" // 2. String Object - created on the heap //String str2 = new String("value"); // String methods String str = "abcdefghijk"; // 01234567890 // char charAt(int paramInt) System.out.println(str.charAt(2)); // prints a char - c // String concat(String paramString) System.out.println(str.concat("lmn"));// abcdefghijklmn System.out.println("ABC".equalsIgnoreCase("abc"));// true System.out.println("ABCDEFGH".length());// 8 // String replace(char paramChar1, char paramChar2) System.out.println("012301230123".replace('0', '4'));// 412341234123 // String replace(CharSequence paramCharSequence1, CharSequence // paramCharSequence2) System.out.println("012301230123".replace("01", "45"));// 452345234523 // All characters from index paramInt // String substring(int paramInt) System.out.println("abcdefghij".substring(3)); // cdefghij // 0123456789 // All characters from index 3 to 6 System.out.println("abcdefghij".substring(3, 7)); // defg // 0123456789 System.out.println("ABCDEFGHIJ".toLowerCase()); // abcdefghij System.out.println("abcdefghij".toUpperCase()); // ABCDEFGHIJ System.out.println("abcdefghij".toString()); // abcdefghij // trim removes leading and trailings spaces System.out.println(" abcd ".trim()); // abcd } }