class level error : expected in java

Question

when I am coding this at class level

int a;
a=5;

it throws error : \"identifier expected\"

But when I declare it as a local variable li

Answer 1

You can not write code into the class, only in method, constructor or into initializer {} block. That is why you get syntax error. Probably you want to use initializer block like this:

class my{
 int a;
 {
  a=1;
 }
}

Answer 2

When you're doing this at class level, you're allowed to combine declaration and assignment in just one statement, like:

class A {
    int a = 5;
}

Otherwise, you have to wrap the assignment withing a block (constructor, method, initializer block). For example:

class A {
    int a;

    public A() { a = 5; } //via constructor

    void setA() { a = 5; } //via method

    { a = 5; } //via initializer block
}

Answer 3

The reason following:

int a=5;

declared at class level does not produce compile time error when:

void m1() {
    int a;
    a=5;
}

is declared because m1() has its own scope.

For instance, if don't declare and access variable a, it would refer to class's field, where as when you declare a locally, you'd always refer to one declared inside a.

PS : You cannot do following at class level:

int a;
a=5;

You'd have to:

int a=5;

Answer 4

Assigning a value to variable is called as expression. We could not write any expression in a class. We could do the same in method bodies. Basically we could right expressions when scope is defined and hence allowed in method.