简单问题：Java中的ValueChanged事件 [英] Simple Question: ValueChanged Event in Java

问题描述

当一个值发生变化时，Java中是否有一个事件触发？像这个例子一样

Is there an event in Java that fires when a value changes? Like in this example

public class Example{
    public String var1 = "Something";
    public Int var2 = 4;
}

如果 var1 或

If var1 or var2 their values change for whatever the event should fire.

推荐答案

答案不是公开暴露你的领域。使该字段私有，引入getter和setter方法，如果值更改，您可以调用setter中的任何内容。

The answer is not to expose your fields publicly to start with. Make the fields private, introduce getter and setter methods, and you can call whatever you like within the setter if the value's changed.

public class Example {
    private String var1 = "Something";

    public String getVar1() {
        return var1;
    }

    public void setVar1(String var1) {
        // TODO: null guards
        if (var1.equals(this.var1)) {
            // No-op - no need to do anything
            return;
        }
        this.var1 = var1;
        notifyListenersOfChangeToVar1();
    }
}

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