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Whether or not java has parameters and return values

First, define a LocalTyrant class

Attribute: name moeney smoke

Behavior 1: (no parameter, no return value):

Behavior 2: (no parameter has a return value):

Behavior 3: (with parameters and return values):

Behavior 4: (with parameters but no return value):

Take a closer look at the following examples

Take your time and don't rush for success.

Package cm.tr;class LocalTyrant {String name; int money; String somke=null; / * * Type 1: no parameter no return value * format: public void method name () {* method body *} * / public void fun1 () {System.out.println (name + "running") Type 2: no parameter and return value * format: public return value type method name () {* method body * return value / / return value must be the same as the return value type *} * / public String fun2 () {String str = "express"; return str / / there must be a return return value} / * * Type 3: return value for parameters * format: public return value type method name (parameter 1, parameter 2, etc.) {* parameters can have multiple parameters Separated by commas * method body * return return value * * / public String fun3 (int money) {if (money > = 25) {somke = "Furong King" } else {somke = "Huangshan";} return somke } / * Type 4: no return value with parameters * format: public returns the value type method name (parameter 1, parameter 2) {* method body * * / public void fun4 (String apple,int money) {System.out.println (name + "charity" + apple + "and" + money + "yuan")) } public String toString () {return "self-introduction:" + name + "RMB with many" + money+ "; / / Type must be String, method name must be toString, cannot modify}} public class Demo2 {public static void main (String [] args) {/ / TODO Auto-generated method stub LocalTyrant th= new LocalTyrant (); th.money= 100; th.name =" Zhang San " / / method 1: System.out.println ("self-introduction:" + th.name + "RMB with many" + th.money+ "); / / method 2: the toString method must be used in conjunction with the public String toString () System.out.println (th.toString ()) in the definition class; / / you can also write / / System.out.println (th) This method will automatically call the toString method / / method 1 call: call the method th.fun1 () with no parameter and no return value; / / method 2 call: call the method with no parameter and return value and must receive the return value to output the returned thing String s = th.fun2 (); System.out.println (s) / / equivalent to System.out.println (th.fun2 ()); / / call method 3: call with return value System.out.println (th.fun3 (50)); String apple = "iphone 6plus"; int money = 100; / / call with method type 4: return value th.fun4 (apple, money) / / equivalent to th.fun4 ("iphone6plus", 100); parameters must be assigned a value of the same type}}

Running result:

Self-introduction: Zhang San has a lot of 100 RMB

Self-introduction: Zhang San has a lot of 100 RMB

Zhang San is running.

Express

Furongwang

Zhang San gave iphone 6plus and 100RMB

PS: it is easy to confuse several methods in java.

The distinction between instance methods, class methods, and constructors in java:

Class methods with static modifiers

Typical main function: public static void main (String args []) {}

Example method: it is a general method

Constructor: no return value (not even void), and the method name is the same as the class name

Public class Test {public static void myMethod (); / / Class method public void myMethod2 (); / / instance method public Teat (); / / Constructor method, which has no return value, and the method name is the same as the class name public String getInfo (); / / this is a method with return value but no parameters, returning the return value and parameter 1, return value of a string type method} method

Except for the constructor, other methods must be declared with a placeholder for the return value, and use void when the method has no return value

The return value uses the return keyword, and there can be multiple return in a method

The declared return value type, which should be consistent with the actual return value type

When a method has a return value, call the method, and you will get the data returned by the method

2. Parameters

Parameter is a special local variable, and there is no need to assign a value in the method body when using it.

The value of the parameter is passed when the method is called by assigning a value in parentheses

There can be multiple parameters in a method, that is, a parameter list

Parameters can be either basic data types or reference data types

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