backspaceoperation.java

简单的计算器程序

package calculate.operations;

import calculate.Calculate;
import calculate.Operation;

public class BackspaceOperation implements Operation {

	public void execute(Calculate calculate) {
		String showText = calculate.getShowText();
		
		if (calculate.isFloat()) {
			calculate.setShowText(showText.substring(0, showText.length() - 1));
		} else {
			if (showText.length() > 2) {
				calculate.setShowText(showText.substring(0, showText.length() - 2) + ".");
			} else {
				calculate.setShowText(Calculate.DEFAULT_SHOW_TEXT);
			}
		}
	}

}