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String s1=LD; - one object

String s1=new String(LD) two objects

Immutability Cannot change string object

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P1

String b=yash;

b.toUppercase();

System.out.println(b);

P2

b=b.toUppercase(); System.out.println(b);

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b

yash

YASH

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String s1=Yash + 3+2;

4 objects are created

(i) Yash (ii) 3

(iii)2

(iv)Yash32

S1=Yash32

Yash

3 2

Yash32

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String s1=3+2+LD

Ans : s1=5LD

String s1=3+2+LD+4+5;

Ans : s1=5LD45

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When u want string from other datatype u can

use this method

For eg:- String s1=String.valueOf(12); s1=12;

String s2=String.valueOf(12.2); s2=12.2

String s3=String.valueOf(true); s3=true

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Equals takes into consideration the case

While equalIgnoreCase does not take into

consideration the case String s1=yash;

String s2=Yash;

If(s1.equals(s2)){

}

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Objects cannot be compared with ==

Can be compared with equals method if that

object overrides equals method of Object class Only two String literals can be compared with

== but not String objects

Program

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String s1=Hello;

String s2=Hello

Is s1==s2 true ?

String s1=Hello;

String s2=new String(s1);

Is s1==s2 true ?

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For Sorting Purpose

Returns < 0 if invoking string is less

Returns > 0 if invoking string is moreReturns == 0 if invoking string is equal to other

String

Apple.compareTo(Banana) 0

S1.compareTo(s2);

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Boolean StartsWith(String str)

Eg. FooBar.StartsWith(Foo) // returns true

Boolean endsWith(Bar)

Eg . FooBar.EndsWith(Bar) // returns true

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CharAt(int location)

For eg. S1=Hello;

S1.CharAt(0)H

S1.CharAt(4)o

int Length() // for array obj it is attrib

byte[ ] getBytes( )

indexOf(String str) subString(int startIndex,int EndIndex)

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Trim()removes white space at the beginning

and end of String

toUpperCase()-converts all characters ofString to uppercase

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Can be changed .represents growable and

rewritable string

Important Methods:-

Int Length( )

Int Capacity()

ensureCapacity(int)

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StringBuilder vs StringBuffer

Methods inside StringBuilder are not

synchronized Everything else is same .

Better to use StringBuilder as it works faster

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Encapsulates runtime environment

instance/obj cannot be directly created

Use static(factory) method getRuntime() to get

instance of RunTime class

Control state and behaviour of JVM

Applets cannot use it without raising security

Exception

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Process Exec(String path)- runs specifiedprogram

Void gc()calls Garbage Collector Long freeMemory()returns free memory in

JVM Long TotalMemory()-returns total memory in the

system Exit (int status)-shuts down currently running

JVM LoadLibrary(String Libname)

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Instance variables

PrintStream in , out , err

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Methods:-

gc()

SetSecurityManager(SecurityManager sm) SecurityManager getSecurityManager()

Exit(int status)

Properties getProperties()

setErr(PrintStream p)

setOut(PrintStream p)

setIn(PrintStream p)

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Program