1. Launching and Debugging a Java program

A Java program can be debugged simply by right clicking on the Java editor class file from Package explorer. Select Debug As → Java Application or use the shortcut Alt + Shift + D, J instead.
也可以直接在代码编辑区右键选择Debug As -> Java Application
https://eclipse.org/community/eclipse_newsletter/2017/june/images/Launching_debugging-1.PNG

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https://eclipse.org/community/eclipse_newsletter/2017/june/images/Launching_debugging-2.PNG

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Either actions mentioned above creates a new Debug Launch Configuration and uses it to start the Java application.
debug配置，选择一个要debug的主类Main class (*.java)
https://eclipse.org/community/eclipse_newsletter/2017/june/images/Launching_debugging-3.PNG

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In most cases, users can edit and save the code while debugging without restarting the program.This works with the support of HCR (Hot Code Replacement), which has been specifically added as a standard Java technique to facilitate experimental development and to foster iterative trial-and-error coding.

2. Breakpoints 设置断点

A breakpoint is a signal that tells the debugger to temporarily suspend execution of your program at a certain point in the code.

To define a breakpoint in your source code, right-click in the left margin in the Java editor and select Toggle Breakpoint. Alternatively, you can double-click on this position.

https://eclipse.org/community/eclipse_newsletter/2017/june/images/Breakpoints-1.PNG

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The Breakpoints view allows you to delete and deactivate Breakpoints and modify their properties.
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All breakpoints can be enabled/disabled using Skip All Breakpoints. Breakpoints can also be imported/exported to and from a workspace.

3. Debug Perspective

The debug perspective offers additional views that can be used to troubleshoot an application like Breakpoints, Variables, Debug, Console etc. When a Java program is started in the debug mode, users are prompted to switch to the debug perspective.

• Debug view – Visualizes call stack and provides operations on that.
• Breakpoints view – Shows all the breakpoints. 可以勾选要设置的断点。
• Variables/Expression view – Shows the declared variables and their values. Press Ctrl+Shift+d or Ctrl+Shift+i on a selected variable or expression to show its value. You can also add a permanent watch on an expression/variable that will then be shown in the Expressions view when debugging is on. 在程序单步运行过程中，可以查看变量的值。
• Display view – Allows to Inspect the value of a variable, expression or selected text during debugging.
• Console view – Program output is shown here. 程序执行情况就显示在Console控制台中。
  进入debug 透视图后，有时候可能看不到Console view。这时，需要把它调出来，拖放到一个合适的位置，便于输入操作数、显示程序运行结果。
  https://eclipse.org/community/eclipse_newsletter/2017/june/images/Debug_Perspective.PNG
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4.Stepping commands

The Eclipse Platform helps developers debug by providing buttons in the toolbar and key binding shortcuts to control program execution.
https://eclipse.org/community/eclipse_newsletter/2017/june/images/Stepping_Commands.PNG

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在一般调试过程中，F6用的比较多。

For more information about debugging visit: Eclipse Stepping Commands Help