Yes . From the eclipse official documentation :
You can specify which regions are folded by default when an editor is opened. Have a look at the Opens the folding preference page Java >Editor > Folding preference page to customize this.
Just click all the checkboxs .Then whenever a .java file is open in the java editor , everything will be collapsed.
Not sure if this options is the new feature for eclipse indigo version (3.7) , so you may have to update your eclipse to indigo if you use older version but cannot find this option.