bluej | 易学教程

流行的JAVA IDE，你都用过哪几款？

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　　每一个Java程序员应该都有一款自己了解的IDE，挑选一款好的JavaIDE能够大大进步程序员的编程功率，一起有些IDE还供给的各式各样的辅助性功用，让人感觉写起代码能够飞起来！　　本文收集整理了几个目前来说比较盛行和热门的JavaIDE，以供读者参阅！　　IntelliJ 　　毋庸置疑，IntelliJ目前来说应该是JavaIDE里面最受欢迎的，也是许许多多Java程序员公认的最好的IDE。能够说运用IntelliJ你将享受到十分高效的Java项目开发，让程序员在一些惯例耗时的工作中解放出来，开发功率将得到十分大的进步。　　主要有以下这些特色：　　智能代码弥补完结基于结构的帮忙高效的生产力简易的版别控制Maven项目内置功用数据流剖析内联调试器Eclipse 　　Eclipse作为曾经JavaIDE的王者，当然现在也仍然是最终欢迎的JAVAIDE之一，Eclipse具有十分活泼的社区以及许多开源插件，还有一些十分实用的开发东西。　　Eclipse具有许多十分有用的特性，比如代码主动构建，还有其他功用包含内置调试器、错误查看、源代码生成、代码重构。一起Eclipse是一个开源的、免费的IDE，甚至能够构建属于自己的插件来习惯你的需求。　　NetBeans 　　NetBeans实际上是SUN公司2000年推出的，旨在构建一个世界级的JavaIDE

Creating and running a Jar file

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问题 I am a beginner in java programming. I have created a package called Comp Project which contains two classes.... ATM: It has various functions to carry out actions of atm screen. Main: This class calls all the functions from ATM and executes them. Now the program is running good and I have to create a jar file. I created a Jar file with the main class selected as Main . But when I try to run it....it doesn't work. The problem is that i don't understand what creating a manifest is...I looked

Write hashset to txt using filewriter

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问题 I am trying to write a hashset to a text file. Normally, I have no issues with writing to txt as it is simple for me. However, in this case I am absolutely clueless. A bit of background about the class: it is a hashset of ComputerScientist objects with 2 fields; name, and field of research (and yes, I know what I put to fill up the hashset does not count, I was only trying to test to see if I could get this to work). I know the basic setup to use filewriter to save strings to hashset which is

Write hashset to txt using filewriter

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Illegal character with Blue J

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问题 Program public class Project_X { public static void main(String[] args){ byte x; int a=270; double b =128.128; System.out.println("int converted to byte"); x=(byte) a; System.out.println("a and x "+ a +" "+x); System.out.println("double converted to int"); a=(int) b; System.out.println("b and a "+ b +" "+a); System.out.println("n double converted to byte"); x=(byte) b; System.out.println("b and x "+b +" "+x); } } error get illegal character:\160 回答1: You copy-pasted the program code using a

Changing the system.out font and color in BlueJ/Java

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问题 Here is a very simple code public class test { public static void main(String[] args) { System.out.println(" Hello "); } } I am using a BlueJ IDE. What I want to do is make the color of the printed output red. And change the font to any custom made font - say Arial Unicode MS. Feel free to make changes to the code above or give detailed instructions if other things are required. Thanks in advance. Edit: BlueJ seems to use a wordpad as a console. That is it Channels the output into wordpad

Method parameter mismatch: Required double, no argument passed

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问题 I am almost complete but when I compile I get the error "Method getUserTax in class IncomeTax cannot be applied to given types; required double; found: no arguments; reason: actual and formal argument lists differ in length" I've gone over my code multiple times and I cannot find where the error is located. It is near the end of the code on the line "userTax = test.getUserTax(); import java.util.Scanner; //Needed for the Scanner Class /** * Write a description of class IncomeTax here. * *

Missing Return Statement?

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问题 This is my code. when I compile using bluej it highlights the last } and says missing return statement. I cant put void because it is a boolean. ANy ideas? public boolean runAJob() { boolean jobsFinished = false; Job firstJob = getCurrentJob(); String jobName = firstJob.getName(); int jobDuration = firstJob.getDuration(); if (!myJob.isEmpty()&& jobDuration > 0 && jobDuration <= myTotalDuration) { myTotalDuration -= jobDuration; myFinishedJobs.add(myJob.get(0)); myJob.remove(0); System.out

How do I enter parameters for an ArrayList in BlueJ?

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问题 In BlueJ, if I write a method that takes an array as a parameter, then when I want to test that method with a method call I have to enter the elements with curly braces, so: {1,2,3} How do I do a method call for an ArrayList ? Here is my code: import java.util.*; public class Test2{ public static int[] toArray(ArrayList<Integer>a){ int len = a.size(); int []b = new int[len]; for(int i = 0; i<len; i++){ b[i] = a.get(i); } return b; } } Now I want to test it in BlueJ, what should I type in the

BlueJ / Java program returning a new array containing the componentwise sum of its arguments

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问题 The following code returns a new array containing the componentwise sum of its arguments (assuming their length is the same), for example if the input arrays are {0,1,2} and {2,2,3} then the out out will be {2,3,5} and if the input arrays have different numbers of elements, the method should return null. public class Sum { public static double[] sum(double a[], double b[]){ if (a.length != b.length) return null; int[] s = new double[a.length]; for(int i=0; i<a.length; i++) s[i] = a[i] + b[i];