Add lang#java doc

docs/layers/lang/java.md

@@ -0,0 +1,53 @@
+# [Layers](https://spacevim.org/layers) > lang#java
+
+This layer is for Java development.
+
+## Install
+
+To use this configuration layer, add `SPLayer 'lang#java'` to your custom configuration file.
+
+
+## Mappings
+
+  Import mappings:
+
+  Mode      Key           Function
+  -------------------------------------------------------------
+  normal    <F4>          import class under cursor
+  insert    <F4>          import class under cursor
+  normal    <leader>jI    import missing classes
+  normal    <leader>jR    remove unused imports
+  normal    <leader>ji    smart import class under cursor
+  normal    <leader>jii   same as <F4>
+  insert    <c-j>I        import missing imports
+  insert    <c-j>R        remove unused imports
+  insert    <c-j>i        smart import class under cursor
+  insert    <c-j>ii       add import for class under cursor
+
+  Generate mappings:
+
+  Mode      Key           Function
+  -------------------------------------------------------------
+  normal    <leader>jA    generate accessors
+  normal    <leader>js    generate setter accessor
+  normal    <leader>jg    generate getter accessor
+  normal    <leader>ja    generate setter and getter accessor
+  normal    <leader>jts   generate toString function
+  normal    <leader>jeq   generate equals and hashcode function
+  normal    <leader>jc    generate constructor
+  normal    <leader>jcc   generate default constructor
+  insert    <c-j>s        generate setter accessor
+  insert    <c-j>g        generate getter accessor
+  insert    <c-j>a        generate getter and setter accessor
+  visual    <leader>js    generate setter accessor
+  visual    <leader>jg    generate getter accessor
+  visual    <leader>ja    generate setter and getter accessor
+
+## Code formatting
+
+To make neoformat support java file, you should install uncrustify. or
+download google's formater jar from:
+
+https://github.com/google/google-java-format
+
+and set 'g:spacevim_layer_lang_java_formatter' to the path of the jar.