Calling Methods in Java
Learn how to declare and call methods in Java, including changing variable values and object references. See examples of method signatures and arrays.
Calling Methods in Java
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Presentation Transcript
Chapter 4 Using Methods
Calling Method CCE JMU CHINA
Worker Method CCE JMU CHINA
Declaring Methods • Worker and calling methods have the same syntax structure. CCE JMU CHINA
**参见程序运行 CCE JMU CHINA
PassTest.java • public class PassTest { • // changeInt（int）方法用于改变int数据值 • public static void changeInt(int value) { • value = 55; • } CCE JMU CHINA
// changeObjectRef（MyDate）方法用于改变MyDate引用变量 public static void changeObjectRef(MyDate ref) { ref = new MyDate(10, 10, 2008); // changeObjectAttr(MyDate) 方法用于改变引用对象的变量 CCE JMU CHINA
public static void changeObjectAttr(MyDate ref) { • ref.setDay(17); • } • } • public static void main(String args[]) { • MyDate date; • int val; • // 赋int val变量值11 CCE JMU CHINA
val = 11; • // 单向传递val值，调用changeInt(int)方法 • changeInt(val); • // 观测val的当前值 CCE JMU CHINA
System.out.println("Int value is: " + val); • // 为date引用赋值，date引用对象MyDate(7, 7, 2007) • date = new MyDate(7, 7, 2007); • //单向传递date值，调用changeObjectRef(MyDate)方法 • changeObjectRef(date); CCE JMU CHINA
// 观测date引用值 • date.print(); • // 调用changeObjectAttr(MyDate)方法， • //通过date改变所引用对象的变量 • // 观测date引用值 • date.print(); • } • } CCE JMU CHINA
运行结果： ---------- java ---------- • Int value is: 11 • MyDate: 7-7-2007 • MyDate: 17-7-2007 • Normal Termination • Output completed (0 sec consumed). CCE JMU CHINA
**参见程序运行 CCE JMU CHINA
Method Signature • method signature is unique • method name +argument list CCE JMU CHINA
public class Point { private int x; private int y; public String toString() { return ("[" + x + "," + y + "]"); } } CCE JMU CHINA
