1.输出
输出有两种格式,请查阅一下代码:
package javabase;
public class TryDemo3 {
public static void main(String [] args){
String name="Tom";
int age=26;
//输出
System.out.println("name:"+name+"\n"+"age:"+age);
System.out.printf("name: %s age: %d",name,age);
//单双引号,单引号一般定义的是一个字符,双引号定义的为字符串类型
String name1="zhang";
char name2='D';
System.out.println("name1:"+name1+"name2:"+name2);
System.out.printf("name1: %s name2: %s",name1,name2);
}
}
注意:第一种采用+拼接;第二种方式不能使用println,需要使用的是printf
2.if判断
package javabase;
public class ifDemo {
public static void main(String [] args){
int score=65;
if (score>=90){
System.out.println("优秀");
}else if (score>70){
System.out.println("良好");
}else if (score>60){
System.out.println("及格");
}else{
System.out.println("不及格");
}
}
}
3.for循环
package javabase;
public class forDemo {
public static void main(String [] args){
int sum=0;
for(int i=1;i<10;i++){
sum=sum+i;
System.out.println(sum);
}
}
}
利用一个for循环,输出一个三角形
package javabase;
public class forDemo {
public static void main(String [] args){
//输出一个三角形
for(int i=1;i<10;i++){
for (int j=1;j<=i;j++){
System.out.print("*");
}
System.out.println();
}
}
}
如何输出一个等腰三角形
梯形package javabase; import java.util.Scanner; public class forDemo { public static void main(String [] args){ int row=4; for (int i=0;i<row;i++){ for(int j=0;j<row-i-1;j++){ System.out.print(" "); } for(int j=0;j<2*i+1;j++){ System.out.print("*"); } System.out.println(); } } }
package javabase;
import java.util.Scanner;
public class forDemo {
public static void main(String [] args){
int row=4;
for (int i=0;i<row;i++){
// for(int j=0;j<row-i-1;j++){
// System.out.print(" ");
// }
for(int j=0;j<i+3;j++){
System.out.print("*");
}
System.out.println();
}
}
}
对于成员变量为私有的,如果要调用,需要先set,后get
public class thisDemo { private String username; private String password; public void setUsername(String username) { this.username = username; } public String getUsername() { return username; } public void setPassword(String password) { this.password = password; } public String getPassword() { return password; } }
thisDemo user = new thisDemo(); user.setUsername("wanglyd"); String u = user.getUsername(); user.setPassword("Qwer1234"); String p=user.getPassword(); System.out.println(u+"\n"+p);