Basic Java Language: Difference between revisions
wikademia>MetaBohemian m →Assignment Operator '=': clarified char literals, reworded float/double |
wikademia>MetaBohemian →Valid Identifiers: added reserved words table |
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=Valid Identifiers= | =Valid Identifiers= | ||
There are several rules for the naming of your variables. Identifiers can be named using all the letters from A through Z (capital or lowercase, you choose), numbers 0-9 and underscore _ and the dollar sign $. The first character of the identifier cannot be a number, but it can be a letter, _ or $. | There are several rules for the naming of your variables. Identifiers can be named using all the letters from A through Z (capital or lowercase, you choose), numbers 0-9 and underscore _ and the dollar sign $. The first character of the identifier cannot be a number, but it can be a letter, _ or $. Identifiers can be no longer than 32 characters. | ||
You can't create two variables with the same identifier; all identifiers must be unique. You also can't use an identifier that is a Java keyword, listed below. [[Flashcards for Java keywords]] provides some assistance in memorizing the concepts behind specific keywords. | |||
<div align=center> | |||
{| class="wikitable" | |||
| <code>abstract</code> | |||
| <code>assert</code> | |||
| <code>boolean</code> | |||
| <code>break</code> | |||
| <code>byte</code> | |||
| <code>case</code> | |||
|- | |||
| <code>catch</code> | |||
| <code>char</code> | |||
| <code>class</code> | |||
| <code>const</code> | |||
| <code>continue</code> | |||
| <code>default</code> | |||
|- | |||
| <code>else</code> | |||
| <code>enum</code> | |||
| <code>extends</code> | |||
| <code>false</code> | |||
| <code>final</code> | |||
| <code>finally</code> | |||
|- | |||
| <code>float</code> | |||
| <code>for</code> | |||
| <code>goto</code> | |||
| <code>if</code> | |||
| <code>implements</code> | |||
| <code>import</code> | |||
|- | |||
| <code>instanceof</code> | |||
| <code>int</code> | |||
| <code>interface</code> | |||
| <code>long</code> | |||
| <code>native</code> | |||
| <code>new</code> | |||
|- | |||
| <code>null</code> | |||
| <code>package</code> | |||
| <code>private</code> | |||
| <code>protected</code> | |||
| <code>public</code> | |||
| <code>return</code> | |||
|- | |||
| <code>short</code> | |||
| <code>static</code> | |||
| <code>strictfp</code> | |||
| <code>super</code> | |||
| <code>switch</code> | |||
| <code>synchronized</code> | |||
|- | |||
| <code>this</code> | |||
| <code>throw</code> | |||
| <code>throws</code> | |||
| <code>transient</code> | |||
| <code>true</code> | |||
| <code>try</code> | |||
|- | |||
| <code>void</code> | |||
| <code>volatile</code> | |||
| <code>while</code> | |||
| | |||
| | |||
| | |||
|} | |||
</div> | |||
Identifiers should also be meaningful, while maintaining practicality. If calculating the sum of a set of numbers, <code>sum<code> is better than <code>cumulativeTotal</code>, but <code>s</code> might be too short. | |||
=Using the Displayer with Variables= | =Using the Displayer with Variables= | ||
This section is about printing to the console using <code>System.out.println();</code>. | This section is about printing to the console using <code>System.out.println();</code>. | ||