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7/28/2019 Lect 7(String)
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7/28/2019 Lect 7(String)
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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