Usage of hints in eclipse

Windows-preferences-java-editor-content Assist
The bottom of the Auto activation option:
Auto activation delay Indicates how many seconds a prompt appears
Auto activation trigger for Java: There is a point inside, which means that if you enter a dot number in Java, you will be prompted later. You can also add other symbols that trigger cues, such as annotations: @, and so on.

In Java, pressing alt+/also triggers a hint.

These are the uses of the hints in eclipse.

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