Java SE Bronze Exam Number: 1Z0-818 (Data Declaration and Use) (October 2020)

Official site: Java SE Bronze

Purpose

: cherry_blossom: ** Java Bronze SE passed **: cherry_blossom:

table of contents

1, Java data type (primitive type, reference type) 2, Declaration and initialization of variables and constants, valid range of values 3, Declaration, creation and use of arrays (one-dimensional arrays) 4, Use command line arguments

1, Java data type (primitive type, reference type)

** Primitive type **

byte 　short 　int 　long 　float 　double 　boolean 　char

** Reference type **

String

2, Declaration and initialization of variables and constants, valid range of values

Variables

Variable.java

class Variable { 
	public static void main(String[] args) {
				
     -- Primitive type --
		byte  a = 1;
		short b = 5;
		int   c = 10;
		long  d = 100L;
		
		float  e = 1.0F;
		double f = 2.00;
		boolean x =  true;
		boolean y = false;
		char z = 'A';
		
	 -- Reference type -- 
		String name = "java";
	}
}

Constant * It is customary to use uppercase letters

Constant.java

class Constant { 
	public static void main(String[] args) {
				
     -- Primitive type --
		final int VALUE = 10;
		
	 -- Reference type -- 
		final String NAME = "java";
	}
}

3, Declaration, creation and use of arrays (one-dimensional arrays)

Array.java

class Array { 
	public static void main(String[] args) {
	
    -- int type --
	int[] numbers = {5, 10, 15, 20};

    -- String type -- 
	String[] subjects = {"Japanease", "Math", "Social", "Sience", "English"};
		
	for (int i = 0; i < numbers.length; i++) {
		System.out.println(numbers[i]);
	}
		
	for (int i = 0; i < subjects.length; i++) {
		System.out.println(subjects[i]);
	}		
     
	}
}

4, Use of command line arguments

CommandLine

> java "Class file name" "Value 1" "Value 2" ...

The main method receives command line arguments as an array of String class

CommandLine.java

class CommandLine { 
	public static void main(String[] args) {

        System.out.println(args[0]);
        System.out.println(args[1]);

        "Frequently used instruction execution statements"
        "Receives one line of string input from the keyboard"
        String s = new java.util.Scanner(System.in).nextLine();
        "Receives one line of integer input from the keyboard"
        int input = new java.util.Scanner(System.in).nextInt();

        System.out.println(s);
        System.out.println(input);
	}
}

Remarks

If you have any ** advice ** or ** comments **, please do: blush: Timely corrections ❗️ 1, Data Declaration and Use 2, Loop statement