CODEWITHSUNDEEP
javaswitch-statementreturnreturn-type
M-R
M-R

Reputation: 431

Method not returning value

Here is my method:

public int power(int x, int n) {    
    switch (n) {
        case 2: return square(x);
        case 3: return cube(x);
        case 4: return hypercube(x);
    }            
}

Compiler is displaying this message:

Method breakpoint:Tester [entry] - power(int, int) - This method must return a result of type int" message.

Can't seem to figure out what the issue is.

I know it's bad practice, but I've been instructed not to store values in a local variable and return it at the end.

What am I missing here?

Upvotes: 2

Views: 1175

Answers (4)

Bohemian
Bohemian

Reputation: 424983

If nis other than one of your cases, nothing will be returned - that's what the compiler is complaining about.

Since your implementation only caters for n being 2, 3 and 4, the most appropriate thing to do is throw an exception:

public int power(int x, int n) {
    switch (n) {
        case 2: return square(x);
        case 3: return cube(x);
        case 4: return hypercube(x);
    }
    throw new IllegalArgumentException("Power must be 2, 3 or 4. Unsupported power: " + n);           
}

The compiler will then be satisfied that all code paths either return something or an exception is thrown.

Upvotes: 4

Mohammed Aouf Zouag
Mohammed Aouf Zouag

Reputation: 17132

Add a default case to your switch : 

case ...: 
    return ...
...
default:
    return 0; // return some default value in case no other case was executed

Note that the default case must return an Integer, otherwise the error shall persist.

Upvotes: 1

Slava Vedenin
Slava Vedenin

Reputation: 60094

You must add default case or return after switch (because Java didn't what retuns if n isn't 2, 3 or 4): 

public int power(int x,int n){

    switch (n) {
    case 2:  return square(x);

    case 3:  return cube(x);

    case 4:  return hypercube(x);

    }            
    return 0;
}

or 

public int power(int x,int n){

    switch (n) {
    case 2:  return square(x);

    case 3:  return cube(x);

    case 4:  return hypercube(x);

    default: return 0;
    }                
}

Upvotes: 0

user5504756
user5504756

Reputation: 

public int power(int x,int n){

switch (n) {
case 2:  return square(x);

case 3:  return cube(x);

case 4:  return hypercube(x);

}
return 0;

}

I guess it's because you don't have main return state. switch case can be bypass if n doesnt initialized correctly but compiler need return value if you define power as a int power () ... If it return 0 you will know n isn't initialized well

Upvotes: 1

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