packagecom.wsy;publicclasscricle{publicstaticvoidmain(String[]args){System.out.println("helloworld");}}publicclassFruit{publicStringcolor;publicFruit(){color="绿色";}publicvoidharvest(){Stringcolor="红色";System.out.println("水果是："+color+"的！");System.out.println("水果已经收获。。。。。");System.out.println("水果原来是："+this.color+"的！");}publicstaticvoidmain(String[]args){Fruitfruit=newFruit();fruit.harvest();}}水果是：红色的！水果已经收获。。。。。水果原来是：绿色的！publicclassCirc{finalfloatPI=3.14159f;publicfloatr=0.0f;publicfloatgetArea(){floatarea=PI*r*r;returnarea;}publicfloatgetCircumference(floatr){floatcircumference=2*PI*r;returncircumference;}publicstaticvoidmain(String[]args){Circcirc=newCirc();circ.r=20;floatr=20;floatarea=circ.getArea();System.out.println("圆的面积为："+area);floatcircumference=circ.getCircumference(r);System.out.println("圆的周长为："+circumference);}}圆的面积为：1256.636圆的周长为：125.663605publicclassAnimal{publicbooleanlive=true;publicStringskin="";publicvoideat(){System.out.println("动物需要吃东西");}publicvoidmove(){System.out.println("动物会运动");}}publicclassBirdextendsAnimal{publicStringskin="羽毛";publicvoidmove(){System.out.println("鸟会飞翔");}}publicclassZoo{publicstaticvoidmain(String[]args){Birdbird=newBird();bird.eat();bird.move();System.out.println("鸟有："+bird.skin);}}动物需要吃东西鸟会飞翔鸟有：羽毛//从控制台获取用户输入的字符串信息importjava.io.*;publicclassInputStreamGetStr{publicstaticvoidmain(String[]args){InputStreamis=System.in;try{byte[]bs=newbyte[50];inti=is.read(bs);//用于诵读输入的字符串所占用的字节数（再加2（这个点不懂））System.out.println("控制台输入的内容："+newString(bs).trim());System.out.println(i);is.close();}catch(IOExceptione){e.printStackTrace();}}}//如何通过OutputStream类向控制台输出字符串信息importjava.io.*;publicclassOutPutStreamWriteStr{publicstaticvoidmain(String[]args){OutputStreamout=System.out;try{byte[]bs="本例使用O