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package how2j.t3;
 
public class bianliang {
    public static void main(String[] args) {
        System.out.println("HelloWorld");
    }
     
}

package how2j.t3;

public class bianliang {
	public static void main(String[] args) {
		System.out.println("HelloWorld");
	}
	
}

package xiangmu;

public class ltem {
		public static void main(String[] args){
			int year ;
			int month;
			int day ;
			String name;
			
			year = 1949;
			month = 10;
			day = 1 ;
			name = "中国";
			System.out.println(name + "诞生时间" + ":"+ year+ "." + month + "." + day + "." );
		}

		}

没有定义kkt变量

int year= 1944; 
String name ="盖伦"；
 System.out.println(name+year);

public class Demo1 {
	public static void main(String[] args) {	
		int age=10;
		char a='a';
		String name="abc";
	}
}

public class bl {
public static void main(String[] args) {
	int year = 1;
	System.out.println(year+"弘昼5");
}
}

public class XueXiJava {
    public static void main(String[] args) {
        //int year, month, day, name;
        int year, month, day;
        String name;

        year = 2001;
        month = 6;
        day = 21;
        //name = ktt;
        name = "ktt";
        System.out.println(year + "." + month + "." + day + "." + name);
    }
}

public class Test8 {
	public static void main(String[] args) {
		 int year, month, day;
		 String name;
	        year = 2001;
	        month = 6;
	        day = 21;
	        name = "ktt";
	        System.out.println(year + "."+ month+"."+day+"."+name);
	}
}

public class xuexiJAVA {
    public static void main(String[] args) {
        int year, month, day;
        String name;
        year = 2001;
        month = 6;
        day = 21;
        name = ktt;
        System.out.println(year + "."+ month+"."+day+"."+name);
    }
}

public static void main(String[] args) {
        int year, month, day;
        String name;
        year = 2001;
        month = 06;
        day = 07;
        name = "张三";
        System.out.println(year + "."+ month+"."+day+"."+name);
    }

public class xuexiJAVA {
    public static void main(String[] args) {
        int year, month, day, name;
        year = 2001;
        month = 6;
        day = 21;
        name ="ktt";
        System.out.println(year + "."+ month+"."+day+"."+name);
    }
}

public class xuexiJAVA {
    public static void main(String[] args) {
        int year, month, day;
        String name;
        year = 2001;
        month = 6;
        day = 21;
        name = 577;
        System.out.println(year + "."+ month+"."+day+"."+name);
    }
}

可以，在上面就是这个类所有的方法都可以使用，也叫全局变量，在方法里叫局部变量意思只有这个方法内可以使用

public class HelloWorld {
	public static void main(String[] args) {
		int year = 1949;
	}
}

package com.how2j;

/**
 * @author Simon.Qi
 * @version 1.0
 * @date 2020-05-20 9:56
 * @since jdk 1.8.0_191
 * 类说明：Demo演示
 */
public class Demo {
    //全部变量（类变量 用static修饰 可以直接在方法内部调用）
    static int year = 2020;

    public static void main(String[] args) {
        // 局部变量（方法内部）
        int year2 = 2020;
        System.out.println("Hello Java " + year);
        System.out.println("Hello Java " + year2);
    }
}

public class XuexiJava {
    public static void main(String[] args) {
        int year, month, day;
        string name = "ktt";
        year = 2001;
        month = 6;
        day = 21;
        System.out.println(year + "."+ month+"."+day+"."+name);
    }
}

都是可以的啊,一个是成员变量,一个局部变量
                      类中方法外为成员变量,内存位置在堆内存,
                      方法内或方法声明上就是局部变量,内存位置在栈内存

//例如
public class One{
      int c=300;  //此处为成员变量，以下main方法和two方法里都是可以使用
      public static void main(String[] args){
      int a=100;  //此处为局部变量 只能作用在main方法里面
      System.out.println(c); //此处打印变量c没有问题，因为c是成员变量
      }
      public static void two(){
      int b=200;  //此处为局部变量 只能作用在two方法里面
      //以下代码报错，因为a变量是属于main方法的变量，two方法无法使用
      //System.out.println(a)
      }
}

1949