我有一个应用程序,让你点击按钮来添加和减去+5或-5和+1或-1从起始值20.我已经设置,以便当点击一个按钮时,它将把它将值写入字符串并显示它,以便用户可以看到他们按下的内容的历史记录。我有一个名为reset()的方法;将起始值重置为20,我想知道如何清除字符串值
add5.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
counter += 5;
updateDisplay();
// add the click history for p1
String tmText = (String) btnPressedTV.getText();
btnPressedTV.setText(tmText + "\n" + String.valueOf(counter));
}
});
sub5.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
counter -= 5;
updateDisplay();
// add the click history for p1
String tmText = (String) btnPressedTV.getText();
btnPressedTV.setText(tmText + "\n" + String.valueOf(counter));
}
});
void reset() {
// TODO Auto-generated method stub
counter = 20;
display.setText(String.valueOf(20));
display.setTextColor(Color.BLACK);
tmText = "";
}
答案 0 :(得分:1)
试试这个..
使用String
中的Global
tmText ,如下所示整数 counter
String tmText;
int counter;
和reset
方法
public void reset()
{
tmText = "";
counter = 20;
}
答案 1 :(得分:0)
确保String
应该是类变量而不是局部变量
要清除调用变量String值,请尝试此
class Sample
{
String str; // class variable (string)
int counter=20; // class variable (integer)
:
:
:
reset.setOnClickListener(new View.OnClickListener() { // button click
@Override
public void onClick(View v) {
str = ""; // you can clear the string value like this
counter = 20; // you can reset the integer value like this
}
});
:
:
:
public void resetfunction() // method
{
str = ""; // you can clear the string value like this
counter = 20; // you can reset the integer value like this
}
:
:
:
}
答案 2 :(得分:0)
您可以通过
为其指定双引号来重置字符串str =“”;
答案 3 :(得分:0)
我建议在您的课程中使用OnClickListener。这里解释的差异是The different OnClickListener implementation ways
以下是一些解释我的意思的代码:
public class MainActivity extends Activity implements OnClickListener {
Button add5;
Button sub5;
Button reset;
int counter;
String tmText;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main_activity);
//init the counter var
counter = 20;
//get handles to the buttons in your xml declaration
add5 = (Button) findViewById(R.id.add5);
sub5 = (Button) findViewById(R.id.sub5);
reset = (Button) findViewById(R.id.reset);
//attach the buttons the onclickListener
add5.setOnClickListener(this);
sub5.setOnClickListener(this);
reset.setOnClickListener(this);
@Override
public void onClick(View arg0) {
switch(arg0.getId()) {
case R.id.add5:
// +5 code
break;
case R.id.sub5:
// minus 5 code
break;
case R.id.reset;
counter = 20;
tmText = "";
}
}
}
如果您要清除文本视图中显示的值:
TextView myTextView = (TextView) findViewById(R.id.myTextView);
myTextView.setText("");