R4R ----> SCJP1.5 Chapter04

Assertion Expression Rules

We can suppose the assume that a number passed into a method (say, methodA()) will never be negative. While testing and debugging, We want to validate our appicationbut we font want to have to strip out print statements, runtime exception handlers, or if/else tests whenwe were done with development More --- >>

this code we can seeee the proper use of assertion and and distinguish appropriate from inappropriate uses of assertions. Identify correct statements about the assertion mechanism. if (x > 2 && y) { // do something } else if (x < 2 || y) { // do something } else { // x must be 2 // do somethi More --- >>

If we 'were using this keyword then we must explicitly enable assertion awareness at compile time. More --- >>

we know whats in this code : int assert = getInitialValue(); if (assert == getActualResult()) { // do something } IN the preceeding code assert is used as an identifier,assert is now a keyword! The bottom line is we can use “assert” as a keyword or as an identifier, but not both..We're More --- >>

If we dont use the -source 1.4 flag, then the default behavior is as though we said to the compiler, “Compile this code as if we didn’t known anything about assert as a keyword, so that I may use the word assert as an identifier for a method or variable.” More --- >>

in the for lop next section is the conditional expresion which is in the evauateon of the boolean values .we can have only one logical expression, but its very complex. for (int x = 0; ((((x < 10) && (y-- > 2)) | x == 3)); x++) { } The preceding code is legal, but the following is not: for More --- >>

When we are trying to labeled for the while loop , we would t make the lable .Within the loop, it should increment the age by one. Every time it goes through the loop, it checks whether the age is 16. > The outer label should appear just before the while loop begins. It does not matter if it is on More --- >>

When we will trying char in the switch case statement value as this case ,Include a default behavior if none of the char values match : > Make sure a char variable is declared before the switch statement. > Each case statement should be followed by a break. > The default value can be located at More --- >>

firstly we have a for statement lets we declare and initialize zero, one, or multiple variables of the same type inside the parentheses after the for keyword. if we would like to declare the same type of variable which is more than one When we 'll need to separate them with commas as follows : for More --- >>

When the programe execute with the break statement, it will immediately move out of the switch block to the next statement after the switch. for the example we have a code : int x = 1; switch(x) { case 1: System.out.println("x is one"); case 2: System.out.println("x is two"); case 3: System.ou More --- >>

We must also know the command-line switches for disabling assertions. java -da com.geeksanonymous.TestClass or java -disableassertions com.geeksanonymous.TestClass More --- >>

The following would be a very bad idea: public void doStuff() { assert (modifyThings()); // continues on } public boolean modifyThings() { x++ = y; return true; } The rule is: An assert expression should leave the program in the same state it was in before the expression! More --- >>

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