Java中的Goto语句

我在Eclipse中执行了以下代码，但其中的GOTO语句无效。 我该如何使用它？

如何在不使用goto语句的情况下使用Break和Continue语句重写上面的代码？

 import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; /** * */ /** * @author Home * */ public class student { /** * @param args */ String average(float sub1,float sub2,float sub3) { float average = (sub1+sub2+sub3)/3; if( average > 50) return "PASS"; else return "FAIL"; } String addName(String name) { return name; } public static void main(String[] args) throws NumberFormatException, IOException { // TODO Auto-generated method stub BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); student stu = new student(); int loop_option = 0; do { System.out.println("--------------STUDENT DETAILS---------------"); System.out.println("Choose the operation from the following options."); System.out.println(" 1.ADDNAME"); System.out.println(" 2.AVERAGE_RESULT"); System.out.println(" 3.EXIT"); System.out.println("CHOOSE THE OPERATION U WANT:"); int option = Integer.parseInt(br.readLine()); switch(option) { case 1: System.out.println("Enter the name"); String name = br.readLine(); System.out.println("The Inserted student name is " +stu.addName(name)); break; case 2: outsideloops: System.out.println("Enter the marks (in 100):"); System.out.println("Subject 1:"); float sub1 = Float.parseFloat(br.readLine()); if (sub1 >= 101) goto outsideloops; System.out.println("Subject 2:"); float sub2=Float.parseFloat(br.readLine()); System.out.println("Subject 3:"); float sub3=Float.parseFloat(br.readLine()); System.out.println("The Student is "+stu.average(sub1,sub2,sub3)+ "in the examinations"); break; case 3: System.exit(0); default: System.out.println("Please choose the valid option"); //break; } System.out.println("if U want 2 use further press 1 to continue..."); loop_option=Integer.parseInt(br.readLine()); } while (loop_option == 1); System.out.println("The STUDENT program is terminating now."); } } 

通过下面的代码，其中一个Stack Overflow成员建议我编写以下代码：但这也是错误的..我在想为什么删除Java中的GOTO语句？

这也不起作用。

 import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; public class Main { String average(float sub1,float sub2,float sub3) { float average=(sub1+sub2+sub3)/3; if( average>50) return "PASS"; else return "FAIL"; } String addName(String name) { return name; } public static void main(String[] args) throws NumberFormatException, IOException { // TODO Auto-generated method stub BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); Main stu = new Main(); float sub1 = 0; int goThere = 0; do { switch(goThere){ case -1: System.out.println("if U want 2 use further press 0 to continue..."); goThere = Integer.parseInt(br.readLine()); continue; case 0: System.out.println("--------------STUDENT DETAILS---------------"); System.out.println("Choose the operation from the following options."); System.out.println(" 1.ADDNAME"); System.out.println(" 2.AVERAGE_RESULT"); System.out.println(" 3.EXIT"); System.out.println("CHOOSE THE OPERATION U WANT:"); goThere = Integer.parseInt( br.readLine() ); continue; case 1: System.out.println("Enter the name"); String name = br.readLine(); System.out.println("The Inserted student name is " + stu.addName(name)); goThere = -1; continue; case 2: System.out.println("Enter the marks (in 100):"); System.out.println("Subject 1:"); sub1 = Float.parseFloat(br.readLine()); goThere = 4; continue; case 4: { if( sub1 >= 101) { goThere = 2; } else {goThere = 3;} } continue; case 3: System.out.println("Subject 2:"); float sub2=Float.parseFloat(br.readLine()); goThere =5; continue; case 5: { if( sub2 >= 101) { goThere = 3; } else { goThere = 6; } } continue; case 6: System.out.println("Subject 3:"); float sub3 = Float.parseFloat(br.readLine()); goThere = 7; continue; case 7: { if( sub3 >= 101) { goThere = 6; } } continue; System.out .println("The Student is " + stu.average(sub1,sub2,sub3) + "in the examinations"); goThere = -1; continue; } break; } while(true); } } 

Answer 1

到目前为止还没有Java中的goto 。 这是一个保留字，以防最终需要它，但据我所知，他们尚未使用它。

可能的等效代码：

 case 2: float sub1 = 0.0; do { System.out.println("Enter the marks (in 100):"); System.out.println("Subject 1:"); sub1 = Float.parseFloat(br.readLne()); } while (sub1 >= 101); ... rest of the code ... 

请注意，此代码对于此特定情况将是等效的。 goto没有通用的替代品; 如果有，他们只是称它为 goto并完成它。 每种情况都不同，替换将完全取决于如何使用goto 。

Answer 2

你不必使用goto（已经没有）Ok。 让我们考虑一下这个问题。 我认为这可能有用

 public class Goto { public static void main(String[] args) { int goThere = 0; do { switch(goThere) { case 0: case 1: System.out.println("Foo"); goThere = 3; continue; case 2: System.out.println("Baz"); goThere = -1; continue; case 3: System.out.println("Bar"); goThere = 2; continue; } } while(false); } } 

尝试这个。 也许你可以扩展该代码。

Answer 3

根据这个 ：

在Java中，goto是保留字，但不可用。

Answer 4

正如其他人指出的那样，Java中没有goto语句。 我想补充说标签是一个轻微的选择。

Answer 5

向前跳

 label: if (true) { // Do stuff if (check) break label; // Do more stuff } 

向后跳

 label: do { // Do stuff if (check) continue label; // Do more stuff break; } while(true); 

它不能用于任何合理的软件;-)

Answer 6

虽然goto是Java中的保留关键字，但没有goto语句。

Answer 7

重写代码就在这里，

把你的“学生”课程放在同一个包中，然后是Main.java;

 package MyPackage import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; public class Main { public static void main(String[] args) throws NumberFormatException, IOException { // TODO Auto-generated method stub BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); Student stu = new Student(); float sub1 = 0; int goThere = 0; do { switch(goThere){ case -1: System.out.println("if U want 2 use further press 0 to continue..."); goThere = Integer.parseInt(br.readLine()); continue; case 0: System.out.println("--------------STUDENT DETAILS---------------"); System.out.println("Choose the operation from the following options."); System.out.println(" 1.ADDNAME"); System.out.println(" 2.AVERAGE_RESULT"); System.out.println(" 3.EXIT"); System.out.println("CHOOSE THE OPERATION U WANT:"); goThere = Integer.parseInt( br.readLine() ); continue; case 1: System.out.println("Enter the name"); String name = br.readLine(); System.out.println("The Inserted student name is " + stu.addName(name)); goThere = -1; continue; case 2: System.out.println("Enter the marks (in 100):"); System.out.println("Subject 1:"); sub1 = Float.parseFloat(br.readLine()); goThere = 4; continue; case 4: if( sub1 >= 101){ goThere = 2; continue; } System.out.println("Subject 2:"); float sub2=Float.parseFloat(br.readLine()); System.out.println("Subject 3:"); float sub3=Float.parseFloat(br.readLine()); System.out.println("The Student is " + stu.average(sub1,sub2,sub3) + "in the examinations"); goThere = -1; continue; } break; } while(true); } }