util/src/com/intellij/openapi/util/LazyInstance.java

   1 /*
   2  * Copyright 2000-2007 JetBrains s.r.o.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  * http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 package com.intellij.openapi.util;
  18
  19 import org.jetbrains.annotations.NotNull;
  20
  21 import java.lang.reflect.Constructor;
  22
  23 /**
  24  * @author peter
  25  */
  26 public abstract class LazyInstance<T> extends NotNullLazyValue<T>{
  27
  28   protected abstract Class<T> getInstanceClass() throws ClassNotFoundException;
  29
  30   @NotNull
  31   protected final T compute() {
  32     try {
  33       Class<T> tClass = getInstanceClass();
  34       Constructor<T> constructor = tClass.getConstructor();
  35       constructor.setAccessible(true);
  36       return tClass.newInstance();
  37     }
  38     catch (InstantiationException e) {
  39       throw new RuntimeException(e);
  40     }
  41     catch (IllegalAccessException e) {
  42       throw new RuntimeException(e);
  43     }
  44     catch (ClassNotFoundException e) {
  45       throw new RuntimeException(e);
  46     }
  47     catch (NoSuchMethodException e) {
  48       throw new RuntimeException(e);
  49     }
  50   }
  51 }