The method of parameter passing

方法传参

• 对于基本数据类型的参数,形式参数的改变,不影响实际参数的值

• 代码实现

public class Test {
    public static void main(String[] args) {
        int number = 100;
        System.out.println("调用change前:"+number);
        change(number);
        System.out.println("调用change后:"+number);
    }
    public  static  void change(int number1){
        number1 = 200;
        return number1;
    }
}

代码解析

 public static void main(String[] args) {    //把mainThe method is loaded into stack memory
    int number = 100;                        //在mainmethod to load one int number   100;
    System.out.println("调用change前:"+number); //将number的值输出
    change(number);                         //调用change方法：把changeThe method is loaded into stack memory
    public  static  void change(int number1){ //在chenge方法中,加载一个 int nember1  100 
                                    //  number1 是形参,Its initial value is the actual parameternumber给它的.实参number的初始值：100
        number1 = 200;              //   number1的值从100 变为了200
        return number1;             //  将number1的值返回到main方法中,暂时mainNo one receives in the method
        }                           //chenge方法结束 int number1 = 200 和changemethod along withchanggThe method ends and disappears in the stack memory
     System.out.println("调用change后:"+number);//再次输出number的值,这次number的值在main方法中,值为100
  }                                 //main方法结束,int number = 100 和mainmethod along withmianThe end of the method disappears in stack memory

• 对于引用类型的参数,形式参数的改变,影响实际参数的值.

• 代码实现

public class Test {
    public static void main(String[] args) {
        int[] arr = {10,20,30};
        System.out.println("调用change前:"+arr[1]);
        change(arr);
        System.out.println("调用change后:"+arr[1]);
    }
    public  static  void change(int[] arr1){
        arr1[1] = 200;
    }
}

代码分析

public static void main(String[] args) {     //把mainThe method is loaded into stack memory
     int[] arr = {10,20,30};    //int[] arr appears in stack memorymain方法中   {10,20,30}will appear in the heap memory,形成2行2列的表格
                                                                //The address value appears above the table001 
                                //will convert the address value001 Assigned to stack memory arr
     System.out.println("调用change前:"+arr[1]);//输出arr[1]的值--->20
     change(arr);               //调用change方法：把changeThe method is loaded into stack memory
      public  static  void change(int[] arr1){在chenge方法中,加载一个 int[] arr1  001 
                                    //  arr1是arr 传递过来的 Also the address value in heap memory is001的数据
          arr1[1] = 200;        //通过arr1--->001--->索引1--->20   ===>20变成200 The data in the heap memory has changed
       }            //chenge方法结束 int number1  001 和changemethod along withchanggThe method ends and disappears in the stack memory 
     System.out.println("调用change后:"+arr[1]);//再次输出arr[1]的值,The data in the heap memory has changed 但是没有消失
       }                        //main方法结束,int[] arr  001 和mainmethod along withmianThe end of the method disappears in stack memory

Basic data types and reference data types are different when passing parameters 

基本数据类型,Actions are passed the value of the variable,Changing the value of one variable does not affect the value of another variable.引用数据类型（类、数组和接口）,Assignment takes a reference to the original object（Can be understood as a memory address）passed to another reference 

 

综合案例

        Use the method with parameters to achieve student information management

                Add student name

                in an array that holds multiple student names,指定查找区间,Find a student name and display whether the search was successful 

package cn.bdqn.demo04;

public class Student {
	/*
	 * Add student name in an array that holds multiple student names,指定查找区间,Find a student name and display whether the search was successful
	 */

	// 定义Student类属性
	String name;
	int age;

	// Define the way to achieve the above requirements：in an array that holds multiple student names,指定查找区间,Find a student name and display whether the search was successful
	public static boolean searchStudent(Student[] students, int startIndex,
			int endIndex, String name) {
		int count = 0;
		for (int i = startIndex; i <= endIndex; i++) {
			if (name.equals(students[i].name)) {
				return true;
			} else {
				count++;
				if (count == (endIndex - startIndex + 1)) {
					return false;
				}
			}
		}
		return false;
	}

}

package cn.bdqn.demo04;

public class StudentTest {

	public static void main(String[] args) {
		//创建Student类对象
		Student stu1 = new Student();
		stu1.name = "张三";
		stu1.age = 20;
		
		Student stu2 = new Student();
		stu2.name = "李四";
		stu2.age = 20;
		
		Student stu3 = new Student();
		stu3.name = "王五";
		stu3.age = 20;
		
		Student stu4 = new Student();
		stu4.name = "赵六";
		stu4.age = 20;
		
		Student stu5 = new Student();
		stu5.name = "孙七";
		stu5.age = 20;
		
		//将上面5students are stored in an array
		Student[] stus = {stu1,stu2,stu3,stu4,stu5};
		

//		Scanner sc = new Scanner(System.in);
//		System.out.println("Please enter the starting subscript of the interval you are looking for：");
//		int startIndex = sc.nextInt();
//		System.out.println("Please enter the ending subscript of the interval you are looking for：");
//		int endIndex = sc.nextInt();
//		System.out.println("请输入你要查找的学生姓名：");
//		String name = sc.next();
		
//		int count = 0;
//		for(int i = startIndex;i<=endIndex;i++){
//			if(name.equals(stus[i].name)){
//				System.out.println("There is the name of the student you are looking for");
//				break;
//			}else{
//				count++;
//				if(count==(endIndex-startIndex+1)){
//					System.out.println("The name of the student you are looking for is not found in the specified range");
//				}
//			}
//		}
		
		boolean result=Student.searchStudent(stus, 1, 3, "赵六");
		System.out.println("There are names you are looking for in the specified range of the array："+result);

	}

}