# Java 引用变量

> 原文： [https://javabeginnerstutorial.com/core-java-tutorial/java-reference-variable/](https://javabeginnerstutorial.com/core-java-tutorial/java-reference-variable/)

引用变量用于引用对象。 它们以无法更改的特定类型声明。

## 引用变量的类型

*   静态变量
*   实例变量
*   方法参数
*   局部变量

## 静态变量示例

```java
class test {
	//below variable is static variable means it is class level variable
	static int i;

	public static void main(String[] args) {
		// As i is an static variable it can be accessed directly without using any object
		System.out.println("Value before calling method1: " + i);
		test t1 = new test();
		t1.method1();
		System.out.println("Value after calling method1: " + i);
		t1.method2();
		System.out.println("Value after calling method2: " + i);
	}

	void method1() {
		i++;
	}

	void method2() {
		i++;
	}

}
```

## 实例/局部/方法参数示例

```java
class MPE {
	// Instance Variable
	int i;

	public static void main(String[] args) {
		/*
		 * Here i is an Instance variable.
		 */
		test t1 = new test();
		System.out.println("Value before calling method1: " + t1.i);

	}

	/*
	 * Here j is a method parameter. And k is a local variable.
	 * 
	 * Note**: Local variables life is only till the end of method
	 */
	void method1(int j) {
		int k;
		i = j;
		/*
		 * Local Variable(k)'s life ends once execution for this method
		 * completes. As k is local is variable it needs to be initialized 
		 * before we can use it. But as it is not getting used here, it can stay here without initializing
		 */

	}
}
```

