JAVA_2Lesson

package test;

 

public class abc {

    public static void main(String[] arg)

    {

        int[][] xx=new int[3][];

        xx[0]=new int[3];

        xx[1]=new int[2];

        xx[2]=new int[1];

        

        for(int i=0;i<xx.length;++i)

            for(int j=0;j<xx[i].length;++j)

                xx[i][j]=j;

        for(int[] i1:xx)

            for(int j:i1)

                System.out.println(j);

        System.out.println(">>>>>>>>>>>");

        int [][] x={{1,2,3},{1,2},{1}};

        System.out.println(x[1][1]);

    }

}

 

package test2_class;

 

public class student {

    String sName;

    String sNumber;

    int sage;

    public String getsName() {

        return sName;

    }

    public void setsName(String sName) {

        this.sName = sName;

    }

    public String getsNumber() {

        return sNumber;

    }

    public void setsNumber(String sNumber) {

        this.sNumber = sNumber;

    }

    public int getSage() {

        return sage;

    }

    public void setSage(int sage) {

        this.sage = sage;

    }

      

    

    void eat()

    {

        System.out.println(sName+" have lunch");

    }

    void sleep()

    {

        System.out.println(sName+" sleep");

    }

    public boolean equals(Object obj)

    {

        student s=(student)obj;

        if(sName==s.sName&&sage==s.sage&&sNumber==s.sName)

        {    

            return true;

        }

        return false;

    }

    public String toString()

    {

        return "name:"+sName+"\t"+"age:"+sage+"\t"+"number:"+sNumber;

    }

    

}

 

package test2_class;

 

public class Main {

    public static void main(String[] args)

    {

        student t=new student();

        t.setsName("zhangsan");

        t.setSage(15);

        t.setsNumber("2678");

        

        System.out.println(t.getSage());

        System.out.println(t.getSage());

        System.out.println(t.getSage());

        t.eat();

        t.sleep();

        if(t.equals(t))

            System.out.println("equal");

        System.out.println(t);

    }

}

    

package string_practice;

 

public class string_practice {

 

    public static void main(String[] args) {

        // TODO Auto-generated method stub

        String str3="HELLO";

        String str4="HELLO";

        String str1=new String("HELLO");

        String str2=new String("HELLO");

        

        if(str3==str4)

        {

            System.out.println("equals");

        }

        if(str1.equals(str2))

        {

            System.out.println("equals");

        }

        

        Integer a = new Integer(1);

    }

 

}

 

类方法中不能访问非static变量.

导入的两个包有相同名的类，则不导入

 

final定义常量的关键