工作中常用的J2EE技术

used for a short time and then unreferenced
　　For each object creation the following occurs:
　　*Memory is allocated on the heap
　　*Class constructors are called
　　*Fields are initialized
　　*The state of the object is tracked
　　Creating many short-lived objects is a common performance bottleneck on the Java platform
　　Temporary Objects
　　*Medium and Short lived objects
　　*Survive less than 2 garbage collections
　　String concatenation example…
　　String objects are immutable
　　Once created, cannot be changed
　　String abc = “a” + b + “c”;
　　Translates to –
　　String abc = new Stringbuffer().append(“a”)
　　.append
　　.append(“c”)
　　.toString();
　　Two new objects are created
　　one StringBuffer and one String
　　String result = “”;
　　For (int i=0; i < 20; i++) {
　　result += getNextString();
　　}
　　Better coded as:
　　String result = “”;
　　StringBuffer buffer = new StringBuffer();
　　For (int i=0; i < 20; i++) {
　　buffer.append(getNextString())
　　}
　　Result = buffer.toString();