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Section 4 : Language Fundamentals


State the effect of using a variable or array element of any kind when no explicit assignment has been made to it.


All the instance and static variables of a class are automatically initialized to their default values before use even if there has not been explicit assignment to them. This is, however, not true for local variables ( variables declared inside a method ). As a result of this, when you try to use a variable without initializing it first, you get their default value. For example, an int variable will be initialized to zero, float will be initialized to 0.0, a boolean will be initialized to false and so on. A reference variable gets initialized to null by default. In case of a local variable, however, your code will not compile if you do not initialize the variable before trying to use it.

All the elements of an array get initialized to their default values, whether the array is an instance or static member of a class, or a local variable of a method. If you try to use an array before initializing it, the compiler will not complain. But you will get a NullPointerException at the runtime, as the array itself will get initialized to null value automatically. If you do initialize the array by using new operator, you will not get this exception at runtime. However, if you have not initialized its elements, all you will get is the default values of its elements.


section4-1 | section4-2 | section4-3 | section4-4

Sections : 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11

 

 

 

 

 

 

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