Whats basic reason to developed java where as many oop language available that era ?

Question

reason behind development of java.

Answer 1

Because the need for a platform-independent (that is, architecture-neutral)
language that could be used to create software to be embedded in various consumer electronic
devices, such as microwave ovens and remote controls.

The trouble with C and C++ (and most other
languages) is that they are designed to be compiled for a specific target. Although it is possible
to compile a C++ program for just about any type of CPU, to do so requires a full C++ compiler
targeted for that CPU. The problem is that compilers are expensive and time-consuming to
create. An easier—and more cost-efficient—solution was needed. In an attempt to find such
a solution, Gosling and others began work on a portable, platform-independent language
that could be used to produce code that would run on a variety of CPUs under differing
environments. This effort ultimately led to the creation of Java.

Now about other langauges
one reason to pick Java (as opposed to .NET or Objective-C) is the ecosystem and its portability and high-level nature, the JVM is increasingly the preferred target for language compilers and interpreters.
Java is more secured programing language, because It maintaines number of its secure checking points Another reason is byte code is executed under JAVA 
Runtime Environment. which has several Security related checking.