Sequence structure
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The basic algorithm structure that any algorithm is inseparable from executing sentence by sentence
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public class shunxv { public static void main(String[] args) { System.out.println("h1"); System.out.println("h2"); System.out.println("h3"); System.out.println("h4"); } }
Choose a structure
if single selection structure
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public class ifDemo01 { public static void main(String[] args) { Scanner scanner = new Scanner(System.in); System.out.println("请输入内容:"); String s = scanner.nextLine(); //equals:判断字符串是否相等 if(s.equals("hello")){ System.out.println(s); } System.out.println("End"); scanner.close(); } }
if double selection structure
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import java.util.Scanner; public class ifDemo02 { public static void main(String[] args) { //考试分数大于60就是及格,小于60就不及格 Scanner scanner = new Scanner(System.in); int score = scanner.nextInt(); if(score>60){ System.out.println("及格"); }else{ System.out.println("不及格"); } scanner.close(); } }
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import java.util.Scanner; public class ifDmeo03 { public static void main(String[] args) { Scanner scanner = new Scanner(System.in); int score = scanner.nextInt(); if(score==100){ System.out.println("恭喜满分!"); }else if(score<100&&score>=90){ System.out.println("A级!"); }else if(score<90&&score>=80){ System.out.println("B级!"); }else if(score<80&&score>=70){ System.out.println("C级!"); }else if(score<70&&score>=60){ System.out.println("C级!"); }else if(score<60&&score>=0){ System.out.println("不及格!"); } scanner.close(); } }
if nested structure
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if(布尔表达式 1){ //布尔表达式1的值为true执行代码 if(布尔表达式 2){ //布尔表达式2的值为true执行代码 } }
if multiple choice structure
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if(布尔表达式 1){ //布尔表达式1的值为true执行代码 }else if(布尔表达式 2){ //布尔表达式2的值为true执行代码 }else if(布尔表达式 3){ //布尔表达式3的值为true执行代码 }else { //如果以上布尔表达式的值都不为true执行代码 }
switch selection structure
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Variable types can be: byte, short, int, char (java se7 supports: string type)
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import java.util.Scanner; public class switchDemo { public static void main(String[] args) { //case穿透,switch匹配一个具体的值 char grade = 'C'; switch(grade){ case 'A': System.out.println("优秀"); break;//跳出 case 'B': System.out.println("良好"); break; case 'C': System.out.println("及格"); break; default: System.out.println("未知等级"); } } }
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