Since the learning of html / css, java script, jQuery has finished Once I summarized my profile, my work so far, and things around me I created a web page. It's a simple page Since it was my first time, I spent about 3 weeks slowly.
I created it while using hover and accordion I struggled a little with the accordion, so be sure to create it again Try to use it and try to get used to it.
Next, we will continue learning Java so that we can create apps.
Java
The basic writing method is decided, there is a method part in the class part, and in that It is in the form of outputting.
System.out.println("Numerical value you want to output");
The above is how to write the output part. Numerical values do not require "" in mathematical formulas! !! (If you add it, it will be judged as a character string.)
It basically consists of data type + variable name. Variable = something like a box to put values (data). Be careful because the data type changes depending on the value you put in the variable!
For example, "int" to enter a numerical value. The variable name that follows is It is good to have something that is easy to see, so in the case of numerical values, it is better to set it to "number". There are many other data types, so some are I will write it below.
Data types that are likely to be used frequently ・ Int ⇒ integer ・ Double ⇒ decimal ・ When boolean ⇒ true or false (true / false value) ・ Char ⇒ 1 character (when using initials etc.) ・ String ⇒ Character string (first uppercase)
An expression of "and", "or", or "not".
・ && ⇒Katsu
・||⇒ or
・ Add! ⇒ Not
Example
!(x<=30)
/*Indicates that x is not less than 30*/
・ If statement ⇒ often used with else if "If XX" ⇒ Output "Otherwise, when XX" ⇒ Output And so on, the output can be changed in some cases.
int x=8;
if(x%2==0){
System.out.println("Even");
}else if(x%2==1){
System.out.println("Odd");
・ Switch statement The previous sentence can be rewritten
int x=8;
switch(x%2){
case 0: /*← If this value is matched, the following processing is executed*/
System.out.println("Even");
break; /*← Be careful not to forget this*/
case 1:
System.out.println("Odd");
break;
}
・ Default You can set the case that does not match any case
....
default
System.out.println("other than that");
break;
}
・ While statement Used when repeating.
int i = 1;
while(i<=10){
System.out.println(i+"It is displayed times.");
i++;
In the above case, from "Displayed once" to "Displayed 10 times." It is displayed continuously. Without [i ++;], it would be an infinite loop, which would be a heavy burden, so don't forget!
・ For statement It is possible to rewrite the while statement earlier with a for statement.
for(int i=1;i<=10;i++){
System.out.println(i+"It is displayed times.");
The way to make it is similar to what I did before One thing to keep in mind is to remember [] after the data type!
String[] names={"Nana","Hana","Mana"};
-Use the for statement to display the arrays in order.
String[] names={"Nana","Hana","Mana"};
for(int i =0;i<names.length;i++){
System.out.println(names[i]);
}
-Further rewrite with an extended for statement
string[] names={"Nana","Hana","Mana"};
for(String name:names){
System.out.println(name);
}
・ I wrote using the extended for statement
/*....Abbreviation*/
int[] numbers={1,4,6,9,13,16};
int oddSum = 0;
int evenSum = 0;
/*First assign an array and then oddSum(Odd)evenSum(Even)Initialize by substituting 0 for*/
for(int number:numbers){
if(number%2==0){
evenSum+=number;
}else{
oddSum+=number;
}
}
/*number%Make an if statement of even number or not with the formula of 2, and write an instruction to add to each*/
System.out.println("The sum of odd numbers is" + oddSum + "is");
System.out.println("The sum of even numbers" + evenSum + "is");
...
by this "The sum of odd numbers is 23" "The sum of even numbers is 26" Is output.
The basics are easy to understand, but when it comes to applications I don't think I really understand it because it's often inflexible. So, I think it would be effective to do the exercises when you forget it. Also, try to practice the exercises as time goes by.
When assigning an array, be careful because you have forgotten the "[]" after the data type many times.
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