java参数传递

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1.代码示例

基本类型作为参数传递

public class TestPass1 {
    public static void testPass(int t){
        t = 2;
    }
    public static void main(String[] args){
        int t = 9;
        System.out.println("Before testPass: t = " + t);
        testPass(t);
        System.out.println("After testPass: t = " + t);
    }
}

结果：

Before testPass: t = 9

After testPass: t = 9

对象作为参数传递

public class TestPass2 {
    public static void testPass(StringBuffer strBuf){
        strBuf.append(" world");
    }
    public static void main(String[] args){
        StringBuffer strBuf = new StringBuffer("hello");
        System.out.println("Before testPass: strBuf " + strBuf);
        testPass(strBuf);
        System.out.println("After testPass: strBuf " + strBuf);
    }
}

结果：

Before testPass: strBuf hello
After testPass: strBuf hello world

对象作为参数传递

public class TestPass3 {
    public static void testPass(StringBuffer strBuf){
        strBuf = new StringBuffer(" world");
    }
    public static void main(String[] args){
        StringBuffer strBuf = new StringBuffer("hello");
        System.out.println("Before testPass: strBuf " + strBuf);
        testPass(strBuf);
        System.out.println("After testPass: strBuf " + strBuf);
    }
}

结果

Before testPass: strBuf hello
After testPass: strBuf hello

2.分析

1.基本类型在java中存放在堆栈中，直接存放的是值。

2.对象类型在java中存放在堆中，而堆中只是存放的该对象的地址，该对象的值放在内存中。

3.所以我们可以从上面例子中看到：

testPass1中传递的是值，所以不会改变

testPass2中其实是传递的该对象的地址，改地址指向该对象，所以会改变

testPass3中传递的是地址，但是该地址又重新指向新对象，所以不会改变

java参数传递

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原文地址：http://www.cnblogs.com/maying3010/p/5837227.html