finally return 与String.replaceAll()

最新推荐文章于 2021-05-17 10:49:04 发布

最新推荐文章于 2021-05-17 10:49:04 发布 · 129 阅读

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本文通过几个具体的Java函数示例，展示了finally代码块在不同情况下的执行效果，并测试了String类的replaceAll()方法。总结了finally块中返回值对函数整体行为的影响及对象引用的变化。

函数finally return 与String replaceAll()测试，代码如下：


/**
 * 函数finally return 与String replaceAll()  测试
 * @author jsl
 * @date 2010-6-8
 */
public class Test {
	public static boolean get() {
		try {
			return false;
		} finally {
			return true;
		}
	}
	public static int get1() {
		int a=0;
		try {
			return a;
		} finally {
			a=4;
		}
	}
	public static int get2() {
		try {
			System.out.println("步骤1");
			if (true)
				throw new Exception("");
			return 1;
		} catch (Exception e) {
			System.out.println("步骤2");
			return 2;
		} finally {
			System.out.println("步骤3");
			return 3;
		}
	}
	public static Object get3() {
		Object o = new Object();
		try {
			System.out.println("first  Object:"+o);
			return o;
		} finally {
			o = new Object();
			System.out.println("second Object:"+o);
		}
	}
	public static Student get4() {
		Student s = new Student();
		try {
			s.name = "jsl";
			return s;
		} finally {
			s.name = "lsj";
		}
	}
	public static void main(String[] args) {
		System.out.println("测试get()...........................");
		System.out.println(get());
		System.out.println("测试get1()...........................");
		System.out.println(get1());
		System.out.println("测试get2()...........................");
		System.out.println(get2());
		System.out.println("测试get3()...........................");
		System.out.println(get3());
		System.out.println("测试get4()...........................");
		System.out.println(get4().name);

		System.out.println("测试String.replaceAll()...........................");
		/**
		 * 特殊字符"."  "\"   "$"  在替换时必须在字符前加 "\\"
		 * 测试代码如下
		 */
		String classPath = "java.lang.String";
		System.out.println(classPath.replaceAll(".", "/"));
		System.out.println(classPath.replaceAll("\\.", "/"));
		System.out.println("abc23abc123$".replaceAll("\\d", "/").replaceAll("\\$", ""));
	}
}

class Student {
	public String name = "";
}

返回结果：


测试get()...........................
true
测试get1()...........................
0
测试get2()...........................
步骤1
步骤2
步骤3
3
测试get3()...........................
first  Object:java.lang.Object@35ce36
second Object:java.lang.Object@757aef
java.lang.Object@35ce36
测试get4()...........................
lsj
测试String.replaceAll()...........................
////////////////
java/lang/String
abc//abc///

结论


finally()代码块如果有返回值，则必会覆盖之前的return的值

如果函数返回的是对象，当finally()代码块修改了返回值对象内容时，则会引起对象的改变，如果是修改了对象的引用，则无效。这个结论类似java传参(都是传值)。