please give me solution for this

root cause

Unable to find a javac compiler;
com.sun.tools.j avac.Main is not on the classpath.
Perhaps JAVA_HOME does not point to the JDK
org.apache.tool s.ant.taskdefs. compilers.Compi lerAdapterFacto ry.getCompiler( CompilerAdapter Factory.java:10 6)
org.apache.tool s.ant.taskdefs. Javac.compile(J avac.java:935)
org.apache.tool s.ant.taskdefs. Javac.execute(J avac.java:764)...