本文介绍了为什么JAVA的foreach不改变元素值?的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
下面怎么打印老板而不是低音? 字符串boss =boss;
char [] array = boss.toCharArray(); (char c:array)
{
if(c =='o')
c ='a';
System.out.println(new String(array)); //如何不打印低音?它打印老板。
您正在更改迭代变量<$ c $ ç> C 。这不会改变数组的内容。迭代变量只是数组元素的一个拷贝。如果你想修改数组,你需要明确地这样做:
$ $ $ $ $ $ $ $ $ $ c $ for(int i = 0; i< array .length; i ++){
if(array [i] =='o'){
array [i] ='a';
$ $ $ $ $ $ $ $ $ $ c $ for(int i = 0; i< array .length; i ++){
if(array [i] =='o'){
array [i] ='a';
你的原始代码是等价的(按照):
for(int i = 0; i< array.length; i ++){
char c = array [i ]。
if(c =='o'){
c ='a';
$ b 改变局部变量的值不会改变任何东西否则 - 只是改变局部变量。作业:
char c = array [i];
拷贝数组中的值变成局部变量。它不会将本地变量与数组元素永久关联。
How come the following prints boss and not bass?
String boss = "boss";
char[] array = boss.toCharArray();
for(char c : array)
{
if (c== 'o')
c = 'a';
}
System.out.println(new String(array)); //How come this does NOT print out bass?It prints boss.
解决方案 You're changing the iteration variable c
. That doesn't change the contents of the array. The iteration variable is just a copy of the array element. If you want to modify the array, you need to do so explicitly:
for (int i = 0; i < array.length; i++) {
if (array[i] == 'o') {
array[i] = 'a';
}
}
Your original code is equivalent (as per section 14.14.2 of the JLS) to:
for (int i = 0; i < array.length; i++) {
char c = array[i];
if (c == 'o') {
c = 'a';
}
}
Changing the value of a local variable will never change anything else - it just changes the local variable. The assignment:
char c = array[i];
copies the value in the array into a local variable. It doesn't associate the local variable with the array element perpetually.
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