Experiment with familiarity with a Java development environment

Experiment with familiarity with a Java development environment

Experimental content

1. Compiling and running a simple Java program using the JDK

2. Edit, compile, run, and debug Java programs using Eclipse

Experimental requirements

1. Students who do not have a Linux base are advised to start with the Linux basics (new version) Vim Editor course

2. Complete the experiment, write the experiment Report, the experiment Report template see QQ Group, pay attention to the experiment report focus is the running result, encounter problem (tool find, install, use, program edit, Debug, run, etc.), solution (empty method such as "Check Network", "Ask classmate", "read book" 0 points) as well as analysis (what can be learned from it, what gains, lessons, etc.).

3. Report the time of your PSP (Personal software Process)

Steps	Take	Percentage
Demand analysis
Design
Code implementation
Test
Analysis Summary

4. Copying is strictly prohibited.

Experimental knowledge points

1. Installation location and difference of JVM, JRE, JDK;

2. command line run JAVAC,JAVA;JAVAC-CP; JAVA-CP;

3. Path,classpath,sourcepath setting method and application;

4. Package management: package;import;javac-d;

5. Eclipse (Netbeans) manages Java projects, debugging: breakpoints, stepping, etc.;

6. Java basic syntax: type and type conversion; variables; operators; Process control, etc.;

7. Use of JDK help documentation;

Experimental steps under Java Program development under the command line Java program development, debugging 1, input on the command line eclipsecommand and enter or click on the desktop Eclipse EEicon to open Eclipse2, click in Eclipse File->New-> Java ProjectNew Java Project 3, enter the project name HelloJDB(You can name it yourself) and click Finishbutton to complete new Project 4, click in Eclipse File->New->ClassNew Java Class 5, enter the package name according to the Java Code specification czw, class name HelloJDB(Capitalize the first letter of the word) and tick the Automatically generate main function option, and then click FinishButton 6, enter the following code: ' 1 package LJP; 2 public class Hellojdb {3 public static void main (string[] args) {4 int i = 5; 5 int j = 6; 6 int sum = Add (i, j); 7 Sy STEM.OUT.PRINTLN (sum); 8
9 sum = 0; Ten for (i=0; i<; i++) sum + = i; 12
SYSTEM.OUT.PRINTLN (sum); 14} 15
+ public static int Add (int augend, int addend) {n int sum = augend + addend;18 return sum; 19} 20}

7. Click the Run button (or use the Ctrl+F11 shortcut key) to see the results of the run in the console. As shown in: 8. Below we practice the debugger, first we open the Window->Open Perspective->Debug debug view by clicking, as shown in:

9. The debugger first sets breakpoints and one- step operation . Setting breakpoints is simple, as shown in:

Then click the Debug button (or use the F11 shortcut key) to start debugging the Java program, and we can see that the program stays on line 4th, as shown in:

Note that at this point the 4th line of code is not executed, we can put the mouse on the variable name to see the value of the variable, the value of I is not 5, we run the program through a single run To line 5th, single-step operation there are two: Step Into( shortcut F5) and stepover(shortcut F5), these two single-step operation function in the run statement, there is no difference in the execution of the function call statement, Step Into will jump into the function implementation, Step Over will directly execute the function, in practice we prefer to use Step Over, only the function execution error, stating that the program problem in the called function, then come back by Step Into entering the function to debug. We click Step Over on the icon (or F6 ), the program stops at line 5th, then look at the value of the variable I, you will see I equals 5.

10. Step execution efficiency is slow, if we feel that the 6th line to the 10th line of code is no problem, want to let the program run directly to line 11th, what to do? First we set the breakpoint on line 11th and then click the Resume icon (shortcut F8 ), and the program runs to line 11th, as shown in:

11. One-Step execution efficiency is slow also leads to another problem, such as a cycle in the middle of a problem? You can then resolve the issue through conditional breakpoints. When debugging the loop code, there is a value that we pay particular attention to when we look at the value of the variable in the Variable tag , for example, we are more concerned at this time, sum each step can see sum the change of the situation,

To set a conditional breakpoint, we right-click on the left side of line 11th and select Breakpoint Properties... as shown: we set the condition "i==50" as shown in: Click F8, we can see that I is 50. As shown in the following:

Mastering the basic skills of these debugs can solve most of the problems you normally encounter, and other debugging methods can be found in resources.

Iii. Exercises (through command LineAnd EclipseImplemented in two ways, the results of the two and the total number of questions after their own study number plus 1Is the number you want to complete, practice debugging under Eclipse 1. Implement the Caesar password and test it. Code:

Import java.io.*;

Import Java.util.Scanner;

public class Kaiser {

Public staticvoid Main (string[] args) {

System.out.println (" Please enter key:");

scanners = new Scanner (system.in);

int a =s.nextint ();

C (a); }

publicstatic void C (int n) {

try{

Charb[];

BufferedReader Br2 = new BufferedReader (Newinputstreamreader (system.in));

System.out.println (" Please enter a clear text:");

Stringstr2=br2.readline ();

B=str2.tochararray ();

System.out.println (" ciphertext:");

int k=n;

For (Inti=0;i<str2.length (); i++) {

Char ch= (char) ((b[i]-' a ' +k)%26+ ' a ');

System.out.print (CH);

}

System.out.println ("\ n key k=" +k);

}

catch (IOException e) {

System.out.println (E.getmessage ());

}

}

}

Iv. problems encountered and solutions

Not very skilled at setting breakpoints, not familiar with some words in English. There is programming Caesar password when not very skilled, ask the other students.

Five, the experimental harvest

Because the school speed is too slag ... Then is directly in the window environment to make the experiment, this experiment let me to the Java code debugging has a further understanding, Eclipse on the error detection and debugging is clear and easy to understand, hope that the future of the experiment can be completed smoothly, in the mistakes of continuous learning, gain more knowledge

Experiment with familiarity with a Java development environment