How to define and call methods with parameters and return values ​​in Java

Definition and call of methods with parameters

Formal parameters and actual parameters

Formal parameters: parameters in method definition

Equivalent to the variable definition format, for example int number

Actual parameters: Parameters in method calls

are equivalent to variables or constants, such as 10, number

Method exercises with parameters

Requirements: Design a method Used to print the maximum number of two numbers, the data comes from the method parameters

Idea:

1. Define a method to print the maximum number of two books, such as getMax()

public static void getMax( ){
}

2. Define two parameters for the method to receive data

public static void getMax(int a,int b){
}

3. Use branch statements to process the size relationship of numbers in two situations;

if (a>b){
          system.out.println(a);
}else{
          system.out.printf(b);

4. Call the defined method in the main method (using constants)

public static void main（String[ ] args）{
//直接传递常量
          getMax（10,20）；
}

5. Call the defined method in the main method (using variables)

public static void main（String[ ] args）{
//定义变量，传递
        int a=10；
        int b=20；
        getMax（a,b）;
}

Code example:

public static void main(String[] args) {
		// TODO Auto-generated method stub
		getMax(10, 20);//使用常量
		int a=10;
		int b=20;
		getMax(a, b);//使用变量
	}
 
	public static void getMax(int a,int b){
		if (a>b){
			System.out.println(a);
		}else{
			System.out.println(b);
		}
	}

Definition and call of methods with return values

Definition of methods with return values

Format:

public static data type Method name ( Parameters) {

                                                                                                                                                                             return data;

#                                                                                                                                                                                   return true;

              return 100; #Method call with return value

Format:

Method name (parameter);

Example:

isEvenNumber(5);

Format 2:

Data type Variable name = Method name (parameter);

Example:

boolean Number = isEvennumber(5);

Note:

The return value of the method is usually received using a variable, otherwise the return value will be meaningless

Sample code: Define a method that receives a parameter, determines whether the data is an even number, and returns true or false

public static void main(String[] args) {
		//数据类型 变量名 = 方法名(参数)
		boolean flag= isEvenNumber(10);
		System.out.println(flag);
	}
	public static boolean isEvenNumber(int number) {
		if(number%2==0){
			return true;
		}else{
			return false;
		}
	}

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