一、Java的基本数据类型和C基本一样

public class Test {
	public static void main(String[] args) {	//main
		int a = 10;
		int b = 20;
		int c = a + b;
		float f = (float)0.1;
		double d = 3.14159;
		
		System.out.println("a="+a);	//printf("a=%d\n",a);
		System.out.println("b="+b);	//printf("b=%d\n",b);
		System.out.println("c="+c);	//printf("c=%d\n",c);
		System.out.println("a="+a +	" b="+b +	" c="+c);	//printf("a=%d b=%d c=%d\n",a,b,c);
		System.out.println(a + "+"	+ b + "=" + c);	//printf("%d+%d=%d",a,b,c);
		System.out.println("f="+f);	//printf("f=%d\n",c);
		System.out.println("d="+d);	//printf("d=%d\n",c);

	}
}

运行结果：

1.public static void main(String[] args)的快速写法：

1. 写main
2. 按Alt+/
3. 回车键

2.System.out.println（）的快速写法：

1. 写syso
2. 按Alt+/

3.连接的‘+’号起到小字符串的作用

二、Java的选择控制流程和C语言一模一样

public class Test {
	public static void main(String[] args) {
		
		int a = 1;
		if(a > 0){
			System.out.println("a是正整数");
			if(a == 1){
				System.out.println("它是正整数，而且是1");
			}else{
				System.out.println("它是正整数，不是1");
			}
			
		}else{
			System.out.println("a是非正整数");
		}
		
		System.out.println("=========================");
		
		switch(a){
			case 1:
				System.out.println("这是1");
				break;
			case 2:
				System.out.println("这是2");
				break;
			case 3:
				System.out.println("这是3");
				break;
		
		}

	}
}

运行结果：

三、Java的循环控制和C语言一模一样

public class Test {
	public static void main(String[] args) {
		int i;
		int j=3;
		
		for(i=0; i<3; i++){
			System.out.println("Hello Wrold from for");
		}
		
		while(i>0){
			System.out.println("Hello Wrold from while");
			i--;
			
		}
		
		do{
			System.out.println("Hello Wrold from do...while");
			j--;	
		}while(j>0);
		
	}
}