计算器从一个数字开始

Question

我正在努力让它在应用程序打开时从一个数字开始，并在这个数字上减去/加1，比如20。因此，当他们点击+1时，它将转到21，而不是从0开始。谢谢你的帮助。

    int counter;
Button add , sub; 
TextView D1;
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.fragment_main);
    counter = 0;
    add = (Button) findViewById(R.id.btn1);
    sub = (Button) findViewById(R.id.btn2);
    D1 = (TextView) findViewById(R.id.txt1);
    add.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            // Adds 1 to the counter
            counter = counter + 1;
            D1.setText(" " + counter);
        }
    });
    sub.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            // Subtract 1 from counter
            counter = counter - 1;
            D1.setText(" " + counter);
        }
    });
}
}

Answer 1

只需使用您选择的值初始化计数器。例如，如果你想让它是20，就做

counter = 20;

或者，如果您希望它是一个随机数，您可以使用random类。

Random generator = new Random();
counter = generator.nextInt(); //If you want it to be any random integer value
counter = generator.nextInt(50); //If you want any random integer value from (inclusively 0,  exclusively 50)

所以它可能看起来像这样：

int counter;
Button add, sub; 
Random generator;
TextView D1;
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.fragment_main);
    generator = new Random();
    counter = generator.nextInt(50);
    add = (Button) findViewById(R.id.btn1);
    sub = (Button) findViewById(R.id.btn2);
    D1 = (TextView) findViewById(R.id.txt1);
    D1.setText(" " + counter);
    add.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            // Adds 1 to the counter
            counter = counter + 1;
            D1.setText(" " + counter);
        }
    });
    sub.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            // Subtract 1 from counter
            counter = counter - 1;
            D1.setText(" " + counter);
        }
    });
}
}