1. Syntax Errors:
Occurs when there is error in sourcecode(when the syntax of the language is not respected).
Example: Missing Semicolon
int a=5 //semicolon is missing
Example: Errors in expression
x=(3+5; //Missing closing parenthesis’)’
y=3+*5; //Missing argument between ‘+’ and ‘*’
2. Semantic Errors: Indicates improper use of statements
Example: Use of non-initialized variable
int i;
i++; //The variable i is not initialized
Example: Type incompatibility
int a=”hello”; // the datatype int and string are not compatible
Example: Errors in expression
string a=”hello”;
int b=5-s; // the operator – does not support arguments of type string
Example 4: Unknown references
- strin x; //strin is not defined
- String s; s.println(); //Println is not method of class String
3. Logical Errors: Occurs in the output of the program. The program is compiled and executed without errors but generating unexpected output comes under logical errors.
Example :
int i=1;
while(i<=1) //Infinite loop does not terminate
System.out.println(i);
4. Run Time Errors: Occurs when the program is running.
Example: Divide by Zero
int a=10,b;
b=a/0; //infinite
Example:
FileReader f=new FileReader(“file.txt”); // Error occurs only when the file “file.txt” not exists on the harddisk.