// Java关键字示例代码
// 1. 使用类和对象的关键字:class, new
class Example {
// 2. 使用访问修饰符关键字:public, private, protected
private int privateVar;
protected int protectedVar;
public int publicVar;
// 3. 使用构造函数和方法的关键字:this
public Example() {
this.privateVar = 0;
this.protectedVar = 0;
this.publicVar = 0;
}
// 4. 使用控制流的关键字:if, else, for, while, switch, case, break, default
public void controlFlowExample(int num) {
if (num > 0) {
System.out.println("Positive number");
} else if (num < 0) {
System.out.println("Negative number");
} else {
System.out.println("Zero");
}
for (int i = 0; i < 5; i++) {
System.out.println("For loop iteration: " + i);
}
int j = 0;
while (j < 5) {
System.out.println("While loop iteration: " + j);
j++;
}
switch (num) {
case 1:
System.out.println("Number is 1");
break;
case 2:
System.out.println("Number is 2");
break;
default:
System.out.println("Number is not 1 or 2");
}
}
// 5. 使用异常处理的关键字:try, catch, finally, throw, throws
public void exceptionHandlingExample() throws Exception {
try {
if (privateVar < 0) {
throw new Exception("Private variable is negative");
}
} catch (Exception e) {
System.out.println("Caught an exception: " + e.getMessage());
} finally {
System.out.println("Finally block executed");
}
}
// 6. 使用继承和多态的关键字:extends, implements, super, abstract, interface
public static class Animal {
public void makeSound() {
System.out.println("Animal sound");
}
}
public static class Dog extends Animal {
@Override
public void makeSound() {
System.out.println("Bark");
}
}
public static abstract class AbstractClass {
public abstract void abstractMethod();
}
public static interface Interface {
void interfaceMethod();
}
public static class ImplementingClass implements Interface {
@Override
public void interfaceMethod() {
System.out.println("Implementing interface method");
}
}
// 7. 使用包和导入的关键字:package, import
// 假设这个文件在 com.example 包中
// package com.example;
// import java.util.*;
// 8. 使用其他关键字:final, static, synchronized, volatile, transient
public final int FINAL_VAR = 10;
public static int STATIC_VAR = 20;
public synchronized void synchronizedMethod() {
// Synchronized block to ensure thread safety
}
public static void main(String[] args) {
Example example = new Example();
example.controlFlowExample(1);
try {
example.exceptionHandlingExample();
} catch (Exception e) {
e.printStackTrace();
}
Animal animal = new Dog();
animal.makeSound();
ImplementingClass implementingClass = new ImplementingClass();
implementingClass.interfaceMethod();
}
}
class
用于定义类,new
用于创建对象。public
, private
, protected
控制成员的可见性。this
引用当前对象实例。if
, else
, for
, while
, switch
, case
, break
, default
用于控制程序流程。try
, catch
, finally
, throw
, throws
用于处理异常。extends
, implements
, super
, abstract
, interface
用于实现继承和接口。package
, import
用于定义包和导入类库。final
, static
, synchronized
, volatile
, transient
用于不同的编程特性。上一篇:java 环境变量
下一篇:java获取当前时间年月日时分秒
Laravel PHP 深圳智简公司。版权所有©2023-2043 LaravelPHP 粤ICP备2021048745号-3
Laravel 中文站