给装修公司做推广的网站,wordpress站点的根目录,wordpress百科汉化,wordpress置顶 显示本人选择了2018spring的课程#xff0c;因为他免费提供了评分机器#xff0c;后来得知2021也开放了#xff0c;决定把其中的Lab尝试一番#xff0c;听说gitlab就近好评#xff0c;相当有实力#xff0c;并借此学习Java的基本知识#xff0c;请根据pku的cswiki做好评分机…本人选择了2018spring的课程因为他免费提供了评分机器后来得知2021也开放了决定把其中的Lab尝试一番听说gitlab就近好评相当有实力并借此学习Java的基本知识请根据pku的cswiki做好评分机器准备请自行下载IJ IDEA可以选择破解专业版感谢伯克利大学和Josh Hug开源如此优质知识
根据前人所说此课程需要200h我第一个同学花费了约30到40天暑假时间学完了估算大概一天5-7h的专精学习时间现在我在学校希望from9.18大概50day可以完成
第一二parts简述了学期任务评估目标与要求测评方法等等。看看就好.
Java的基础知识
public class HelloWorld{public static void main(String[] args){System.out.println(hello world);}
}
public class HelloWorld{public static void main(String[] args){int x0;while(x10){System.put.println(x);xx1;}xhorse;}
}
1. Before Java variables can be used, they must be declared. 2. Java variables must have a specific type. 3. Java variable types can never change. 4. Types are verified before the code even runs!!!
public class LargerDemo{
/** Returns the Larger of x and y.*/public static int larger(int x, int y) {if (x y) {return x;}return y;}public static void main(String[] args){System.out.println(larger(-5, 10));}
}
/*
1. Functions must be declared as part of a class in Java. A function that is part of a cLass is calLed a method. So in Java, all functions are methods.
2. To define a function in Java, we use public static. We will see alternate ways of defining functions Later.
3. ALL parameters of a function must have a decLared type,
and the return value of the function must have a decLared type. Functions in Java return onLy one value!
*/why在jdk23中要求编译以上文件 C:\Users\eve\IdeaProjects\newprojects\src\Main.java java: 类 LargerDemo 是公共的, 应在名为 LargerDemo.java 的文件中声明OK我知道了只要把文件名修改一下即可 lab1和homework0都很简单。是对Java的简单应用。可能cmd部分很有用不过你应该在linux部分进行了详细学习git你也是学习使用过了
发现joshhug.gitbooks.io/hug61b是课程教案一样的东西.
Creating and Defining Classes
我们只在cmd输入ls进入到HelloWorld.java文件中javac HelloWorld.java即可编译运行但是得到了class文件这时我们Java HelloWorld就可以解释运行成功输出helloworld
public class Dog{public static void makeNoise(){System.out.println(Bark!);}
}
public class DogLauncher{public static void main(String[] args){Dog. makeNoise();}
}
我们实从类中例一个对象
public class Dog{public int weightInPounds;public /*static*/ void makeNoise(){ if (weightInPounds 10){System.out. println(yip!);} else if (weightInPounds 30){ System.out. println(bark.);} else{System.out. println(woooof!);}}
} 运行后我们按照编译器信息删除static然后创建一个d的dog.重复执行
public class DogLaimcher{public static void main (String[] args)Dog d new Dog();d.weightInPounds51;d.makeNoise();}
}
构造函数
public Dog(int w){wewightInPoundsw;
}
这样可以Dog dnew Dog51d.makeNoise成功运行
现在阐述为什么去掉static因为使用了其中的实例变量与static冲突这使编译器感到困惑 缺少对下面此图片部分笔记 你可以拥有一个静态和非静态的类,把他们混合
public class Dog{
public int weightInPounds;
public static String binomenCanis familiaris
/*创建一个适用于所有狗的变量可以在对象dd2或者Dog使用*/public Dog(int w){weightInPoundsw;
}
public void makeNoise(){if (weightInPounds 10){ System.out. println(yip!); }else if (weightInPounds 30){ System.out. println(bark.); }else{System.out. println(woooof! ); }
}
public static Dog maxDog(Dog d1, Dog d2){ if (dl. weightInPounds d2.weightInPounds) {return d1;}return d2;
}public Dog maxDog(Dog d2){/*非静态方法因为是由特定的dog进行判断*/if (this.weightInPoundsd2.weightInPound){return this;}return d2;
}
}
在一个类中定义的变量或方法也称为该类的成员. 使用类名访问静态成员,例如Dog.binomen. 不能使用类名调用非静态成员:Dog.makeNoise 静态方法必须通过特定的实例访问实时变量,例如d1.
比如我们删除这个方法Dog maxDogDog d2编译器报错。对于非静态成员如果只有一个方法的非静态版就不能用类名来运行函数如果有一个静态方法并且想访问某种实例变量必须指明是哪个实例比如里面的this.
回答以下代码会输出什么
public class DogLoop {public static void main(String[] args) {Dog smallDog new Dog(5);Dog mediumDog new Dog(25);Dog hugeDog new Dog(150);Dog[] manyDogs new Dog[4];manyDogs[0] smallDog;manyDogs[1] hugeDog;manyDogs[2] new Dog(130);int i 0;while (i manyDogs.length) {Dog.maxDog(manyDogs[i], mediumDog).makeNoise();i i 1;}}
public static class Dog {/* Size of the dog in standard dog size units. */public int size;/* This is a constructor. It tells us how to construct* dogs from our ideal notion of dogness. */public Dog(int s) {size s;}public void makeNoise() {if (size 10) {System.out.println(hideous yapping);} else if (size 30) {System.out.println(bark!);} else {System.out.println(woof!);}}/* Return the larger of dog d1 and dog d2. */public static Dog maxDog(Dog d1, Dog d2) {if (d1.size d2.size) {return d1;}return d2;} }
}这是一个java可视化网站 Java Visualizer (uwaterloo.ca)对以上问题做出回答
一点扩展在creating and defining classes9/10中0.0-2.20的话
现在要求创建一个程序ArgsSum打印出命令参数的总和假设他们是数字
public class ArgsSum {public static void main(String[] args) {int N args.length;int i 0;int sum 0;while (i N) {sum sum Integer.parseInt(args[i]);/*string to int的方法*/i i 1;}System.out.println(sum);}
}Libraries库的使用 推荐使用stackoverflow
普林斯顿大学library请做project0
