Eclipse
JDK
Java到底有多火爆,先看看一下TIOBE 编程语言社区排行榜,TIOBE是编程语言流行趋势的一个指标,每月更新,参考性很强。看下图:
2、接下来展示在Java学习中,几个很实用的小例子,来帮助我们深圳理解Java。编程的世界,Hello World:代码如下:public static void main(String[] args) { System.out.println("Hello World"); }Java最最主要的方法,main方法,程序的入口,简单,使用,有效,作用大。源文件:HelloJava.Java编译之后的字节码文件:HellJava.class
3、Java面向对象的调用,和++的计算:public class LightJava { private int i = 5; public int getLight(LightJava lj){ return lj.i++; //System.out.println(lj.i++); } public static void main(String[] args) { LightJava l1 = new LightJava(); LightJava l2 = new LightJava(); l1.getLight(l2); System.out.println(l1.getLight(l2)); System.out.println(l2.getLight(l2)); }}
4、方法的调用,类和方法的调用规则,这个最好用debug来一步一步的执行,g观察他的调用规则:public class MethodAndMethod { int i = 1; void first(){ System.out.println("This is test "+i); } void second(){ first(); } public static void main(String[] args) { MethodAndMethod mam = new MethodAndMethod(); mam.second(); }}
5、内部类和接口的使用,注意,只打印what is ? two:interface inter{ void method();}public class interTest { public void method(inter in){ } public static void main(String[] args) { interTest inte = new interTest(); inte.method(new inter() { @Override public void method() { System.out.println("what is ?"); } }); System.out.println("what is ? two"); }}
6、static的使用:public class StaticTest { static int one = 1; int two = 1; public static void main(String[] args) { StaticTest s1 = new StaticTest(); StaticTest s2 = new StaticTest(); System.out.println("s1.one++:"+s1.one++); System.out.println("s2.one++:"+s2.one++); System.out.println("s1.two++:"+s1.two++); System.out.println("s2.two++:"+s2.two++); }}
7、Scanner和Out,输入输出的学习:public static void main(String[] args) { Scanner can = new Scanner(System.in); int i1 = 0; int i2 = 0; try{ System.out.println("请输入第一个数:"); i1 = can.nextInt(); System.out.println("请输入第二个数:"); i2 = can.nextInt(); int i3= i1+i2; System.out.println("你输入的是:"+i3); }catch (Exception e) { System.out.println("你输入的值不符合要求"); } }
debug
run