warining is coming while using Map why? code here

[nagaraj raja]

 import java.util.*;
class testStatic {

public static void main(String[] args){
Map o=new TreeMap();
o.put("n2dmock",new Double(101.4));

Map o2=new TreeMap();
o2.put("n2dmock",new Double(101.4));
System.out.println(o.equals(o2));
}
}
 

 C:\nag\mock>javac  testStatic.java
Note: testStatic.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
 
C:\nag\mock>javac -Xlint testStatic.java
testStatic.java:6: warning: [unchecked] unchecked call to put(K,V) as a member o
f the raw type java.util.Map
                        o.put("n2dmock",new Double(101.4));
                             ^
testStatic.java:9: warning: [unchecked] unchecked call to put(K,V) as a member o
f the raw type java.util.Map
                        o2.put("n2dmock",new Double(101.4));
                              ^
2 warnings
 

[reubin haz]

That's because those collections do not know what type parameters will be.

If you place <String, Double> behind Map and TreeMap, those warnings will disappear

[Barry Gaunt]

If you are studying for SCJP 1.4 be sure to use the Java 1.4.2_* compiler.
Otherwise read up on generics.