by irisxzy

TraceTable, For, Array, Break, Boolean, Logical Expression in if-Statement

ConversionTable

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Initially, I forgot to add i!=1 in the if statement. Therefore, the program will output a “\n” when i=1. Drawing trace table can help me to find out this kind of problem in the future.

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PrimeNumber

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Attention HERE! There are two new methods involved: Break Statement & Boolean.

The break statement has two usages: inside loop or inside switch.

When the break statement is encountered inside a loop, the loop is immediately terminated and the program will go to the next statement following the loop. In this case, if (i%j==0), break statement will be invoked. Then it will directly terminate the second forLoop statement for(int j=2;j<i;j++){}.

Boolean only has two possible value: true or false. While I was programming, a simple “=” completely altered my result. You can see that the sentence boolean prime=false has one “=” while if(prime==true){} has “==”(two equal marks).

Why? That is because what inside if statement is logical expression, we should always write like if(x==0). However, boolean prime=false is an declaration and assignment statement while only requires one “=”.

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Mutiplesof3

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Stars

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GradeAverage

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I created an int Array called anArray which contained num index numbers. Then ask the user to enter the value of each index within Array anArray. sum+=anArray[i]; means sum=sum+anArray[i].

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Trace Table

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Personal Reflection: I feel that JAVA is getting more and more difficult now. It always take time to write a working program since there are always errors involved which are difficult for you to figure out. Debugger is a very useful tool to trace your errors. Try to use it!

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