DAY4

流程控制

break、continue

package basic;

import java.sql.SQLOutput;

public class a11continue {
public static void main(String[] args) {
int i = 0,j=0;
while (i <= 100) {
i++;
System.out.print(i+"\t");
if (i == 5) {
break;
}
}
while(j<=100){
j++;
if(j%10==0){
System.out.println();
continue;
}
System.out.print(j+"\t");
}
}
}

打印三角形

package basic;

public class a12printtriangle {
public static void main(String[] args) {
for (int i = 0; i < 5; i++) {
for(int j=5;j>i;j--){
System.out.print(" ");
}
for (int k=0;k<=i;k++){
System.out.print(" * ");
}
for (int l=0;l<i;l++){
System.out.print(" * ");
}
System.out.println();
}
}
}

debug

方法

System. out. print("*")

类.对象.方法

package basic;

public class a13method {
public static void main(String[] args) {
int s=add(3,5);//实际参数：实际调用给传输他的数据
test();
System.out.println(s); }
public static int add (int a,int b){ //形式参数：定义作用
// 定义数值 public ublic static *** （）{}
return(a+b);
}
public static void test(){//不用返回值就用：public static void *（）{}
for (int i = 0; i < 5; i++) {
for(int j=5;j>i;j--){
System.out.print(" ");
}
for (int k=0;k<=i;k++){
System.out.print("");
}
for (int l=0;l<i;l++){
System.out.print("");
}
System.out.println();
}
}
}


package basic;

import java.util.Scanner;

public class a14reload {//重载
public static void main(String[] args) {
max(10.1,20.1,10.1);

}

public static void max(int a, int b) {
    if (a > b) {
        System.out.println("max="+a);
    } else {
        if (a<b) {
            System.out.println("max="+b);
        }
            else{
                System.out.println("数值相等");
            }

        }
    return ;
    }
public static void max(double a, double b,double c) {
    if (a > b) {
        System.out.println("max="+a);
    } else {
        if (a<b) {
            System.out.println("max="+b);
        }
        else{
            System.out.println("数值相等");
        }

    }
    return ;
}
}

package abb;

public class a9 {
public static void main(String[] args) {
for(int i=0;i<args.length;i++){
System.out.println("args["+i+"]"+args[i]);
}
}
}

使用cmd命令运行包

包运行的时候要到scr目录来：
F:\JAVA\TEST\untitled\src\abb>javac a9.java
F:\JAVA\TEST\untitled\src>java abb.a9 vic xiao is gennius

可变参数 （编写中注意的点，语句要熟悉，用法要固定）

package abb;

import com.sun.org.apache.xpath.internal.objects.XNumber;

public class a10 {
public static void main(String[] args) {
max(2,3,6,43);
max(new double[]{1,2,3});
}

public static void max(double...numbers) {
    if (numbers.length==0){
    System.out.println("no numbers");
    return;}

double result = numbers[0] ;
for(int i=1;i<numbers.length;i++){
if(numbers[i]> result ){
result=numbers[i];
}
}
System.out.println("max="+result);
}
}

递归

package basic;

public class a15digui {
public static void main(String[] args) {
System.out.println(f(5));
}

public static int f(int n) {
    if(n==1){
        return 1;
    }else {

return n*f(n-1);
}

}

}